ﺑﺎﺯﮔﺸﺖ ﺑﻪ ﺻﻔﺤﻪ ﻗﺒﻠﯽ
خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
نسخه الکترونیک
medimedia.ir

Treatment of enterococcal infections

Treatment of enterococcal infections
Literature review current through: Jan 2024.
This topic last updated: Aug 25, 2022.

INTRODUCTION — Enterococcal species can cause a variety of infections, including urinary tract infections, bacteremia, endocarditis, and meningitis. The antimicrobial agents available for treatment of enterococcal infection are reviewed here, followed by treatment approaches for clinical syndromes caused by enterococci. Other issues related to enterococci are discussed in detail separately. (See "Mechanisms of antibiotic resistance in enterococci" and "Vancomycin-resistant enterococci: Epidemiology, prevention, and control" and "Microbiology of enterococci".)

Infections due to Enterococcus faecalis tend to be more virulent than infections due to Enterococcus faecium. In addition, bacteremia due to E. faecalis is more likely to be associated with endocarditis than bacteremia due to E. faecium. Clinical isolates of E. faecalis tend to be considerably more susceptible to beta-lactam agents than clinical isolates of E. faecium, with isolates of E. faecalis testing susceptible to ampicillin, whereas most E. faecium isolates are resistant to ampicillin (minimum inhibitory concentration ≥16 mcg/mL). Another susceptibility trait that helps distinguish these two species is that isolates of E. faecalis are resistant to quinupristin-dalfopristin while E. faecium isolates are usually susceptible to quinupristin-dalfopristin.

CLINICAL APPROACH

Approach to susceptible strains — Enterococci are less susceptible to penicillin and ampicillin compared with most streptococci; even when these cell wall–active agents inhibit enterococci, they often do not kill them; vancomycin is even less bactericidal. E. faecium clinical isolates are more resistant to penicillin than E. faecalis (minimum inhibitory concentration for 90 percent of strains [MIC90] >16 mcg/mL versus 2 to 4 mcg/mL, respectively); MICs of ampicillin are usually one dilution lower than those of penicillin. Piperacillin activity is similar to that of penicillin, and imipenem generally is active against penicillin-susceptible E. faecalis. Cell wall-active agents with less or no clinically relevant activity against enterococci include nafcillin, oxacillin, ticarcillin, ertapenem, most cephalosporins, and aztreonam.

Enterococci are also relatively impermeable to aminoglycosides, and the serum concentrations of aminoglycosides required for bactericidal activity are much higher than can be achieved safely in humans. However, the simultaneous use of a cell wall-active agent raises the permeability of the cell so that an intracellular bactericidal aminoglycoside concentration can be achieved [1]. Bactericidal antimicrobial activity is warranted in clinical circumstances of life-threatening infection. (See 'Approach to specific infections' below.)

Enterococcal isolates are usually tested for susceptibility to ampicillin, penicillin, and vancomycin. The presence of beta-lactamase (identical to one found in Staphylococcus aureus) is very rare; it confers resistance to penicillin and ampicillin when large numbers of organisms are present (such as in the setting of a valvular vegetation), even though the organism may test susceptible using standard laboratory inocula. Thus, to rule out this possibility in patients with life-threatening enterococcal infection (such as meningitis or endocarditis), some experts recommend that the isolate be screened for beta-lactamase production with nitrocefin, a chromogenic cephalosporin, even if ampicillin susceptible. There are also rare reports of more highly penicillin- and/or imipenem-resistant isolates of E. faecalis with retained ampicillin susceptibility (MIC ≤8 mcg/mL) albeit with higher-than-usual MICs [2,3]; this has been associated with specific amino acid changes in the low-affinity penicillin-binding protein (PBP4) of E. faecalis and mutations in the promoter for the gene [4]. If using a beta-lactam antibiotic other than ampicillin (ie, penicillin or piperacillin) in treating severe enterococcal infections, we suggest verification of isolate susceptibility to penicillin by the clinical microbiology lab.

Traditionally, the standard of care for severe enterococcal infection (such as endocarditis) has been penicillin or ampicillin combined with an aminoglycoside to generate synergistic bactericidal activity. A newer regimen, the combination of ampicillin and ceftriaxone, has yielded clinical cure rates equivalent to that of ampicillin plus gentamicin for E. faecalis endocarditis regardless of whether the isolates expressed high-level aminoglycoside resistance [5]. In general, we favor the combination of ampicillin and ceftriaxone as it avoids the toxicity of aminoglycosides [1].

For circumstances in which penicillin or ampicillin plus an aminoglycoside is used to generate bactericidal activity, the isolate should be tested for high-level resistance to gentamicin and streptomycin. If the organism is reported as susceptible to high levels of an aminoglycoside ("SYN-S" indicates "susceptible to synergism"), then it may be assumed that synergism will be achieved when that aminoglycoside is combined with ampicillin; an aminoglycoside should never be used alone for treatment of enterococcal infection. Strains that are resistant to high levels of gentamicin are resistant to synergism with tobramycin, netilmicin, and amikacin (in addition to gentamicin), but some of these strains lack high-level resistance to streptomycin and thus will still demonstrate synergism with that agent [6,7]. (See 'Approach to specific infections' below.)

Even for strains lacking high-level resistance to gentamicin, tobramycin, and, particularly, amikacin should be avoided. All E. faecium are resistant to synergism with tobramycin due to a species-specific aminoglycoside acetyl transferase, and the majority of E. faecium and E. faecalis fail to show synergism with amikacin.

Ampicillin or penicillin are the preferred cell wall-active agents to use with an aminoglycoside; vancomycin should be substituted only in the setting of high-level beta-lactam resistance or hypersensitivity with an inability to desensitize [8]. Combinations of ampicillin or penicillin with gentamicin or streptomycin are preferable to vancomycin-aminoglycoside combinations since the latter pose a greater risk of nephrotoxicity. Gentamicin is more convenient since determination of serum gentamicin concentrations is more readily available than serum streptomycin levels. As mentioned above, amikacin and tobramycin are generally avoided, and laboratories do not test these aminoglycosides.

Antibiotic regimens and doses for treatment of bacteremia due to susceptible strains are outlined in the table (table 1).

Approach to resistant strains — The major categories of resistant enterococci include those with high-level penicillin and ampicillin resistance, those with high-level aminoglycoside resistance, and those with vancomycin resistance [9].

High-level penicillin resistance — Penicillin/ampicillin resistance is usually due to alterations in PBP-5, a low-affinity PBP of E. faecium. In addition, penicillin/ampicillin resistance (MIC ≥16 mcg/mL) generally indicates that the strain is E. faecium.

In the setting of infection due to such organisms when bactericidal therapy is needed (eg, endocarditis), vancomycin (or teicoplanin, where available), or daptomycin (8 to 10 mg/kg intravenously [IV] daily) could be used with an aminoglycoside. In the presence of high-level aminoglycoside resistance or concern for nephrotoxicity, high-dose daptomycin (10 to 12 mg/kg IV daily) may be used; daptomycin may also demonstrate synergism with or enhancement by other agents such as ampicillin. If resistance is due to beta-lactamase production, ampicillin-sulbactam may be used as the cell wall agent. Success with high-dose ampicillin and high-dose ampicillin-sulbactam (in conjunction with aminoglycosides) has been described in case reports (for strains resistant to ampicillin that did not produce beta-lactamase) [10,11].

Regimens and doses for treatment of bacteremia due to enterococci with high-level penicillin resistance are outlined in the table (table 2).

High-level aminoglycoside resistance — When using an aminoglycoside to achieve synergistic, bactericidal therapy (eg, in the setting of endocarditis), testing of enterococci should include high-level aminoglycoside-resistance testing for both gentamicin and streptomycin, since one agent may have activity even when the other does not. Aminoglycoside monotherapy should never be used, and a cell wall-active agent should only be combined with an aminoglycoside to which the organism is found to be "synergism susceptible." Aminoglycosides reported as "SYN-R" (for "resistant to synergism") or as MIC ≥500 mcg/mL of gentamicin or ≥2000 mcg/mL of streptomycin should not be used; other aminoglycosides should generally be avoided.

Combination beta-lactam therapy is an option for treatment of infective endocarditis (IE) due to E. faecalis with or without high-level aminoglycoside resistance. Benefit from double beta-lactam combinations may be due to saturation of different penicillin-binding protein targets. The combination of ampicillin with ceftriaxone demonstrated efficacy in experimental endocarditis due to E. faecalis strains that were highly resistant to aminoglycosides and in treatment of E. faecalis endocarditis in humans. [5,12,13].

Regimens and doses for treatment of endocarditis and other infections due to enterococci with high-level aminoglycosides resistance are discussed in detail separately [5]. (See "Antimicrobial therapy of left-sided native valve endocarditis", section on 'Resistance to penicillin, aminoglycosides, and vancomycin'.)

Vancomycin resistance — The optimal approach for treatment of enterococcal infection due to vancomycin-resistant E. faecium is uncertain. One agent, linezolid, is US Food and Drug Administration (FDA) approved for treatment of infections caused by vancomycin-resistant enterococci (VRE; prior FDA approval of quinupristin-dalfopristin has been removed). The utility of this agent for treatment of endocarditis is uncertain, although there are anecdotal cases suggesting some utility. The resistance profile of VRE isolates should be evaluated carefully in conjunction with infectious diseases expertise when selecting appropriate therapy for such organisms. The approach to treatment of such isolates should be assessed in each individual case. (See 'Approach to specific infections' below.)

Vancomycin-resistant E. faecium isolates often have concurrent high-level resistance to beta-lactams and aminoglycosides. In contrast, vancomycin-resistant E. faecalis are usually susceptible to penicillin and ampicillin, as are E. gallinarum and E. casseliflavus (which are intrinsically vancomycin resistant). The newer agents, linezolid, daptomycin, and tigecycline, have activity against both vancomycin-resistant E. faecalis and E. faecium, whereas quinupristin-dalfopristin has activity against E. faecium but not E. faecalis.

Regimens for treatment of bacteremia due to VRE are outlined in the table (table 2).

Approach to specific infections — Important infections due to enterococci include urinary tract and wound infections, bacteremia, endocarditis, and meningitis. Urinary tract infections (UTIs) generally do not require bactericidal therapy, and urinary catheter-associated bacteriuria often resolves with removal of the catheter. When therapy for enterococcal urinary tract isolates is indicated, monotherapy is sufficient. In the setting of invasive infections such as endocarditis, meningitis, and bacteremia (in the setting of valvulopathy and/or critical illness), bactericidal activity is warranted (although linezolid has been successful in vancomycin-resistant E. faecium meningitis). In such cases, synergistic activity of penicillin or ampicillin in combination with gentamicin (or streptomycin), or ampicillin plus ceftriaxone (or cefotaxime), is generally required (E. faecalis). Testing for high-level resistance to gentamicin and streptomycin should be performed when combination therapy with an aminoglycoside is considered. (See 'Approach to susceptible strains' above.)

In general, determining the clinical significance of an enterococcus recovered from a patient should be tailored to individual patient circumstances, since isolation of an enterococcus does not necessarily require targeted therapy. Enterococci can also be colonizers (such as in respiratory specimens or urinary catheters) or part of a mixed infection (such as in polymicrobial cultures in the setting of intra-abdominal surgery or traumatic wounds) for which therapy is being administered for more virulent organisms. E. faecalis infections tend to be more virulent than E. faecium and therefore should command greater attention when the clinical significance of culture data is in question.

It should be noted that, even when an acute infection due to VRE has resolved, in many cases, fecal colonization may persist for prolonged periods of time.

Urinary tract infection — The urinary tract is the most common site from which enterococci are recovered; this may result from urinary colonization, simple cystitis, complicated UTI including pyelonephritis, perinephric abscess, or prostatitis [14]. Most enterococcal UTIs are nosocomial and/or associated with obstruction, urinary catheterization, or instrumentation [15-17]. In one study of uncomplicated cystitis in premenopausal women, growth of enterococci from a midstream urine culture was not predictive of bladder bacteriuria as assessed by a contemporaneously collected catheter urine sample [18]. Thus, recovering enterococci from the urine of otherwise healthy young females reporting symptoms of cystitis may not necessitate treatment of this organism, especially if another uropathogen is present. Bacteremia in the setting of enterococcal UTI is relatively uncommon [19].

Management should include removal of urinary catheters if possible; this intervention alone has been observed to resolve enterococcal urinary catheter-associated infections/colonization in some cases [20]. If susceptibility is documented, the best options for oral therapy of enterococcal lower UTIs are amoxicillin, nitrofurantoin, or fosfomycin; dosing is outlined in the table (table 3) [21]. Nitrofurantoin achieves excellent therapeutic levels in the urine but is not adequate for treatment of pyelonephritis or enterococcal infection at other sites. Fosfomycin has FDA approval for treatment of uncomplicated UTIs caused by E. faecalis (as well as Escherichia coli), although many E. faecium strains are also susceptible to fosfomycin [22,23]. IV ampicillin may also be considered (see below).

Alternative oral agents include linezolid or a fluoroquinolone, although data on their efficacy for the treatment of enterococcal UTIs are limited; the latter should not be used as monotherapy in the setting of bacteremia since achievable serum levels of fluoroquinolones are frequently close to the minimum inhibitory concentrations [24-32].

For patients with complicated UTI and for patients unable to tolerate oral therapy, the majority of strains are E. faecalis and ampicillin is the drug of choice. Aminopenicillins generally achieve high urinary concentrations with oral or IV administration [33]; an IV dose of 1 gram every 6 hours is reasonable for uncomplicated UTIs. Higher doses may be needed if there is evidence of pyelonephritis or concurrent bacteremia. Vancomycin is an appropriate alternative if the organism is susceptible.

For patients with lower urinary tract disease initially treated with a parenteral regimen with clinical improvement and whose isolate demonstrates beta-lactam susceptibility, completion of therapy with oral amoxicillin may be sufficient. (See "Acute complicated urinary tract infection (including pyelonephritis) in adults and adolescents", section on 'Directed antimicrobial therapy'.)

For UTIs due to ampicillin- and vancomycin-resistant E. faecium strains, ampicillin may still be effective even for strains of E. faecium with ampicillin MIC >64 mcg/mL, since ampicillin is concentrated in the urine. In two small retrospective studies, cure rates for treatment of UTI due to ampicillin-resistant VRE with aminopenicillins (oral amoxicillin or IV ampicillin) and non-beta-lactams were similar (84 versus 88 percent, respectively) [34,35]. Linezolid (excreted approximately 30 percent unchanged in the urine) or daptomycin are other considerations. For UTI caused by vancomycin-resistant E. faecalis, ampicillin should suffice since vancomycin and ampicillin resistance have not been reported together in the same E. faecalis isolate.

There are no specific clinical data on the duration of therapy for enterococcal UTIs. For uncomplicated cystitis, we suggest 5 days of therapy. A longer duration of 7 to 10 days may be warranted for complicated infections, depending on patient circumstances and clinical response.

Bacteremia — Portals of entry for enterococcal bacteremia include the gastrointestinal tract, the urinary tract, intravascular catheters, and wounds (such as ulcers or burns) [14,36-40].

We believe that antimicrobial therapy for enterococcal bacteremia is generally warranted in the setting of two or more positive blood cultures, a single positive blood culture accompanied by signs of sepsis, or a single positive blood culture together with a positive enterococcal culture from another usually sterile site.

Many experts favor deferring antimicrobial therapy for enterococcal bacteremia in the setting of an immunocompetent patient with a single positive blood culture in the absence of clinical evidence for sepsis or in patients who have a polymicrobial infection and are improving on appropriate therapy for a more virulent organism [41,42]. For circumstances in which an intravascular catheter is the likely source of the bacteremia, catheter removal alone may be sufficient to cure the infection. However, if febrile, most patients should be empirically started on antibiotics after detection of enterococci and after additional cultures are obtained, while awaiting sensitivity results; such therapy can generally be discontinued after five to seven days if symptoms have resolved, repeat cultures drawn at 24 hours are negative, and no valvular abnormality is found.

Most cases of enterococcal bacteremia due to species other than E. faecalis are not associated with endocarditis [15,36,38,43-46]. The relative risk of endocarditis in patients with E. faecalis bacteremia is higher but still relatively low, unless the bacteremia is prolonged, of community onset, has an unclear source, or when a prosthetic valve is present. Septic shock in the setting of enterococcal bacteremia is uncommon and should raise suspicion for a polymicrobial infection with accompanying gram-negative bacilli. (See "Intravascular non-hemodialysis catheter-related infection: Treatment".)

A bedside clinical score may be a useful tool for prediction of endocarditis and need for echocardiogram in some patients with enterococcal bacteremia. The DENOVA score uses six criteria with each counting for one point: duration of symptoms ≥7 days; evidence of embolization; number of positive blood cultures (two or more); unknown origin of bacteremia; prior heart valve disease; auscultation of a heart murmur. A cutoff score <3 points suggested a very low risk for enterococcal IE, with a sensitivity and specificity of 100 percent and 85 percent, respectively [47].

In the absence of suspected endocarditis or critical illness, enterococcal bacteremia may be treated with monotherapy (table 1 and table 2) [39,41,48].

Treatment of bacteremia due to susceptible enterococci consists of ampicillin; vancomycin (or teicoplanin, where available) may be administered in the setting of beta-lactam resistance or allergy.

For bacteremia due to ampicillin-resistant, vancomycin-susceptible E. faecium, reasonable therapeutic choices include vancomycin (or teicoplanin where available) or daptomycin (8 to 10 mg/kg/day); high-dose ampicillin may be used if the ampicillin MIC is ≤32 mcg/mL. (See 'Daptomycin' below.)

For bacteremia due to ampicillin- and vancomycin-resistant E. faecium, daptomycin (8 to 10 mg/kg/day) or linezolid (administered orally or IV) are reasonable therapeutic choices; high-dose ampicillin may be used if the ampicillin MIC is ≤32 mcg/mL [49]. We prefer daptomycin if a parenteral agent is needed; linezolid is a useful drug if a patient may be treated with oral therapy. (See 'Daptomycin' below.)

When therapy is deemed warranted, optimal duration of antimicrobial therapy for treatment of enterococcal bacteremia is uncertain. For uncomplicated infection, five to seven days of therapy is likely adequate if repeated blood cultures drawn at 24 hours are negative.

In the setting of suspected endocarditis or critical illness, combination therapy should be given (table 1). For E. faecalis, we favor the regimen of ampicillin plus ceftriaxone since it avoids the toxicity of aminoglycosides; use of a cell wall-active agent in combination with a synergistically active aminoglycoside is also acceptable, with penicillin or ampicillin preferred over vancomycin [50].For ampicillin-susceptible E. faecium, there is little information because such infections are rare; the combination of a cell wall-active agent plus an aminoglycoside (if no high-level resistance) may be preferred, since one in vitro study found that the combination of ampicillin plus ceftriaxone was not reliably active for all isolates, despite low ampicillin MICs [51]; on the other hand, demonstration of in vitro synergism can be concentration dependent. We feel that ampicillin plus ceftriaxone would still be a consideration if there is high-level resistance to all aminoglycosides, if there is high risk of aminoglycoside nephrotoxicity or if toxicity appears during aminoglycoside therapy. Data on combination regimens for treatment of enterococcal endocarditis are outlined in detail separately. (See "Antimicrobial therapy of left-sided native valve endocarditis", section on 'Enterococci'.).

The optimal approach for treatment of nonendocarditis infections caused by resistant enterococci is uncertain. Linezolid is the only drug approved by the FDA for treatment of bacteremia due to VRE, although it is a bacteriostatic agent and was approved in an era when relatively few treatment options were available. Daptomycin, a bactericidal agent, is FDA approved for vancomycin susceptible E. faecalis in skin and skin structure infections; there were insufficient vancomycin-resistant strains or E. faecium for FDA approval for these organisms. It has become an important agent for treatment of severe VRE infection based on its in vitro profile, despite absence of randomized clinical trials [52]. Some meta-analyses suggested a survival benefit of linezolid over daptomycin [53-55] but are limited by methodologic shortcomings of the underlying literature. Conversely, a retrospective cohort study including 644 patients noted treatment with linezolid was associated with significantly higher treatment failure and greater 30-day all-cause mortality compared with daptomycin [56]. Further study is needed.

In the setting of a prosthetic valve and sustained high-grade bacteremia, the duration should reflect presumed endocarditis/intravascular infection (even in the absence of echocardiographic evidence for vegetation); the approach is outlined separately. (See "Antimicrobial therapy of prosthetic valve endocarditis".)

Endocarditis — The approach to selection of antimicrobial therapy for treatment of enterococcal endocarditis is discussed in detail separately. (See "Antimicrobial therapy of left-sided native valve endocarditis" and "Antimicrobial therapy of prosthetic valve endocarditis".)

Patients with enterococcal endocarditis and unclear source of infection appear to warrant colonoscopy [57,58]. This was suggested in a retrospective study including 142 patients with IE due to E. faecalis who underwent colonoscopy; the overall rate of colorectal disease was 70.4 percent, and the prevalence of advanced adenomas and colorectal carcinoma was 14.8 percent [58]. Since most patients with enterococcal endocarditis are also in an age group that should be considered for colonoscopy, this seems a reasonable approach.

Meningitis — Enterococci rarely cause meningitis in normal adults [59]. Most cases of enterococcal meningitis occur in patients with head trauma, neurosurgery, intraventricular or intrathecal catheters, or anatomic defects of the central nervous system (CNS) [60,61]. Rarely, enterococcal meningitis can be a complication of high-grade bacteremia in patients with enterococcal endocarditis or immunodeficiency such as acquired immunodeficiency syndrome (AIDS) or hematologic malignancy [59,60]. Enterococcal meningitis is also seen in the setting of neonatal sepsis and has also been described in association with Strongyloides hyperinfection [62,63].

The optimal approach for treatment of enterococcal meningitis is not certain. Combination therapy is warranted; options for treatment of meningitis are outlined in the table (table 4) [59,60,64]. For infection due to E. faecalis, we favor treatment with ampicillin, ceftriaxone, and gentamicin (assuming high-level resistance to gentamicin is not present), despite the lack of clinical studies supporting this regimen. We favor once-daily aminoglycoside, for the theoretical possibility that higher peaks would favor greater cerebrospinal fluid penetration. For patients failing to respond to systemic antibiotics, addition of intraventricular antibiotics (vancomycin or daptomycin +/- gentamicin) may be reasonable. Daptomycin has poor CNS penetration; if used for treatment of CNS infection, daptomycin should be administered intraventricularly as well as IV [65]. (See "Infections of cerebrospinal fluid shunts".)

Treatment of enterococcal meningitis caused by E. faecium strains resistant to penicillin, aminoglycosides, and vancomycin is a difficult challenge; we favor IV linezolid. If there is a lack of response, we favor daptomycin (IV and intraventricular). Quinupristin-dalfopristin (IV plus intraventricular) is an alternative choice although experience with intraventricular administration is limited [65-78]. Rifampin (if susceptible) may be a useful adjunctive agent, as might intraventricular gentamicin added to intraventricular daptomycin [79-81]. Chloramphenicol should not be used for treatment of enterococcal meningitis. Tigecycline has been used in case reports with either intraventricular daptomycin or intraventricular tigecycline [82].

The precise duration of therapy for enterococcal meningitis is uncertain. In concurrence with the Infectious Diseases Society of America clinical practice guidelines for health care associated ventriculitis and meningitis, we suggest treatment for at least 10 days [83]. If multiple cultures are positive, it is reasonable to extend treatment for 10 to 14 days after the last positive culture.

ANTIBIOTIC AGENTS

Parenteral agents with VRE activity

Linezolid — Linezolid is a bacteriostatic, synthetic oxazolidinone antibiotic that is US Food and Drug Administration (FDA) approved for use in vancomycin-resistant enterococci (VRE) infections. It binds to the peptidyltransferase center of the 50S ribosome, preventing peptide bond formation and thus the addition of new amino acids [84]. Resistance can emerge from mutations or by acquisition from other organisms; a mobile gene, cfr, encoding a methyltransferase that modifies 23S ribosomal ribonucleic acid (rRNA), which confers resistance to linezolid as well as clindamycin, chloramphenicol, pleuromutilins, and streptogramin A, has been found in staphylococci [85,86] and more recently in enterococci [87]. Other plasmid-borne resistant determinants, such as optrA and poxtA, encode ribosomal protection factors that leads to increased minimum inhibitory concentrations (MICs) for oxazolidinones (linezolid and tedizolid) and chloramphenicol [88,89].

Linezolid may be given orally (the preferred route when feasible) or parenterally. It has high bioavailability after oral administration, and it achieves therapeutic levels in most tissues.

Early data on linezolid were obtained in the setting of compassionate use programs. One report describing its compassionate use in nearly 500 patients with a variety of VRE infections (46 percent bacteremia, 10 percent endocarditis, 31 percent catheter infection) reported a cure in 81 percent of cases [90]. Another report describing its compassionate use in 85 solid organ transplant recipients with VRE infection (43 with bacteremia) demonstrated resolution of infection in 63 percent of cases [91]. However, linezolid failure and resistance have also been reported [92,93].

Safety concerns limit the use of linezolid, particularly in the setting of prolonged use. Adverse effects include thrombocytopenia, anemia, lactic acidosis, peripheral neuropathy, and ocular toxicity. When administered with serotonergic agents (particularly selective serotonin reuptake inhibitors), linezolid can induce serotonin syndrome due to its inhibition of monoamine oxidase [94,95]. (See "Serotonin syndrome (serotonin toxicity)".)

Thrombocytopenia associated with linezolid use appears to occur more frequently in the setting of end-stage kidney disease and typically resolves after discontinuation of the drug [96]. Neuropathy (peripheral and, less commonly, optic) as well as lactic acidosis are uncommon but important side effects of linezolid. Peripheral neuropathy can be severe and may not resolve after drug discontinuation [97-99].

Appropriate linezolid dosing is 600 mg every 12 hours orally or intravenously (IV). Blood counts and serum chemistries should be monitored at least weekly during linezolid therapy.

Daptomycin

Clinical use — Daptomycin is a bactericidal cyclic lipopeptide antibiotic that causes depolarization of the bacterial cell membrane [100]. It was approved by the FDA for treatment of skin and skin structure infections, including those caused by vancomycin-susceptible E. faecalis. Daptomycin is likely efficacious for treatment of skin and skin structure infections due to vancomycin-resistant E. faecalis or E. faecium, although the number of isolates in the study was insufficient to support FDA approval. For some strains, including ones with decreased daptomycin susceptibility, daptomycin is potentiated by the addition of ampicillin and/or ceftaroline, even in the setting of resistance to these agents [101,102], and several anecdotal cases have reported using ampicillin plus daptomycin for E. faecalis endocarditis [103]. Potentiation still occurs with strains that became nonsusceptible strains via the liaFSR pathway but not when the organism used the yyc pathway to become nonsusceptible [104,105].

Some favor the use of daptomycin for treatment of E. faecium infections that are resistant in vitro to ampicillin and vancomycin, particularly bloodstream infections, even though daptomycin has not been approved by the FDA for E. faecium [106-108]. The daptomycin MICs for E. faecium are higher than those for E. faecalis, which in turn are higher than those for staphylococci. Data suggest that many enterococcal strains with a daptomycin MIC of 3 to 4 mcg/mL already have mutations that can eliminate the bactericidal activity of the antibiotic, yet were previously reported as susceptible [109-112]. (See 'Susceptibility breakpoints' below.)

The addition of ampicillin or ceftaroline (even in the setting of resistance to these agents) may enhance binding of daptomycin and increase its activity, as mentioned above [101,102,104,105]; some favor use of these combinations for severe infection including VRE endocarditis [113].

FDA approved daptomycin dosing for complicated skin and skin structure infections is 4 mg/kg IV once daily. Minimum dosing for bloodstream infections is 6 mg/kg IV once daily (the approved dose for staphylococcal bacteremia).

In the setting of enterococcal bloodstream infections, and particularly endocarditis, we favor higher daptomycin doses of 8 to 12 mg/kg/day. This is supported by both clinical and pharmacodynamic data [49,114-117]. In a study of 114 patients treated with daptomycin monotherapy, a free drug area under the concentration-time curve to MIC ratio (fAUC/MIC) threshold of >27.43 was predictive of patient survival. Using a Monte Carlo simulation, the authors calculated only a 1.5 to 5.5 percent probability of achieving this target using a 6 mg/kg/day dose of daptomycin for isolates with an MIC of 4 mcg/mL [114]. A second study of 240 patients that examined the probability of achieving therapeutic levels of daptomycin based on pharmacokinetic modeling found a 100 percent probability of threshold attainment at a 10 mg/kg/day dose for isolates with MICs of 2 mcg/mL or less, and 95.2 percent probability at 12 mg/kg/day for isolates with an MIC of 4 mcg/mL [115]. A retrospective study of more than 900 patients with VRE bacteremia in the Veterans Affairs hospital system found that high-dose daptomycin regimens (≥10 mg/kg/day) were associated with reduced 30-day mortality (risk ratio 0.83, 95% CI 0.74-0.94) compared with standard-dose (6 mg/kg/day) and medium-dose (8 mg/kg/day) regimens, respectively [49]. Both medium- and high-dose regimens were also associated with improved rates of microbiologic clearance compared with standard dosing. A study of 112 patients from Taiwan reported similar results; higher dose regimens (≥9 mg/kg/day) associated with lower mortality (20 percent) compared with medium (7 to 9 mg/kg/day) and standard (<7 mg/kg/day) doses (33 and 50 percent, respectively) [116]. Among the small number of patients treated with higher dose therapy, treatment appeared to be safe and no dose dependent association between daptomycin and creatine kinase elevation was seen.

Clinical data supporting combination therapy are less robust. An analysis of daptomycin combination therapy regimens (mostly with beta-lactams) found that combination therapy increased survival at a lower fAUC/MIC threshold than daptomycin monotherapy (fAUC/MIC ratio >12.3 for combination versus >27.4 for monotherapy) [115]. In a small observational cohort study of 114 patients with VRE bacteremia treated with daptomycin (n = 27; 23.7 percent) or daptomycin plus a beta-lactam (n = 87; 76.3 percent), no significant differences in mortality between the two groups were seen at the end of therapy [118]. A subgroup analysis comparing patients treated with high-dose daptomycin (≥9 mg/kg/day) plus a beta-lactam with patients receiving daptomycin monotherapy or low-dose daptomycin plus a beta-lactam demonstrated increased survival in the high-dose combination group; however, the observational nature of the study and small number of patients warrant further study. For vancomycin-resistant E. faecium bacteremia with daptomycin MICs in the 3 to 4 mcg/mL range, we favor combination therapy with high-dose daptomycin plus ampicillin and suggest management in consultation with an infectious diseases specialist.

Patients receiving daptomycin should be evaluated regularly for clinical evidence of myopathy [119]. Serial measurements of serum creatine kinase should be obtained at least weekly (more often in the setting of renal insufficiency); the drug should be discontinued in patients with symptomatic myopathy and creatine phosphokinase (CPK) ≥5 times the upper limit of normal (ULN) or in asymptomatic patients with CPK ≥10 times ULN.

Susceptibility breakpoints — The original Clinical and Laboratory Standards Institute (CLSI) daptomycin breakpoints for enterococci considered strains with a daptomycin MIC of ≤4 mg/L as susceptible. In 2019, the Enterococcus spp CLSI breakpoints were revised [120]. For E. faecium, CLSI lists no S category; an MIC of ≤4 mcg/mL is considered susceptible dose dependent based on a dose of 8 to 12 mg/kg/day, and an MIC of ≥8 mcg/mL is considered resistant. For other Enterococcus spp, an MIC of ≤2 mcg/mL is considered susceptible, an MIC of 4 mcg/mL is considered intermediate, and an MIC of ≥8 mcg/mL is considered resistant, based on a dose of 6 mg/kg/day. In August 2020, the FDA also revised their breakpoints to match the CLSI breakpoints for vancomycin-susceptible E. faecalis; however, these breakpoints are only for the FDA-approved indication of complicated skin and soft tissue infections at a dose of 4 mg/kg/day. The FDA has not recognized any breakpoints for E. faecium because of a paucity of data on E. faecium strains and dosing regimens.

The CLSI recommends only the broth dilution method with Mueller-Hinton broth adjusted to a final calcium ion concentration of 50 mg/L. However, data suggest that MIC determination for daptomycin by both broth microdilution and Etest is unreliable and with poor interlaboratory reproducibility [121]. Due to the apparent inaccuracy of the tests, clinical judgment should be exercised when treating "daptomycin-susceptible" VRE bacteremia and other deep-seated infections with this antibiotic. (See "Mechanisms of antibiotic resistance in enterococci".)

Oritavancin — Oritavancin is a semisynthetic glycopeptide that inhibits cell wall synthesis and has in vitro bactericidal activity against staphylococci and enterococci, including vancomycin-resistant strains [122-124]; its activity appears to be increased against some VRE by an aminoglycoside (if no high-level aminoglycoside resistance is present). There are no trial data to support its use for VRE, although there have been anecdotal reports of its use [125]. Oritavancin was approved in 2014 for treatment of acute bacterial skin and skin structure infections due to susceptible organisms, including E. faecalis [126]. The drug has a half-life of 100 hours, allowing for single-dose therapy for skin and skin structure infections.

Data on oritavancin are discussed further separately. (See "Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Treatment of skin and soft tissue infections", section on 'Dalbavancin, oritavancin, and telavancin'.)

New-generation tetracycline derivatives — Tigecycline, eravacycline, and omadacycline are new-generation tetracycline antibiotics with in vitro bacteriostatic activity against many gram-positive pathogens (including methicillin-resistant S. aureus [MRSA], VRE, and penicillin-resistant Streptococcus pneumoniae), some gram-negative bacteria (important exceptions include Pseudomonas, Proteus, Providencia, and Morganella species), anaerobes, and atypical species.

Tigecycline does not have FDA approval for treatment of VRE, although it has been approved for treatment of complicated skin and skin structure infections and intra-abdominal infections, including infections in which vancomycin-susceptible E. faecalis were recovered. Many VRE isolates are susceptible to tigecycline, based on in vitro and animal model data, and MICs of tigecycline are usually lower for E. faecium than for E. faecalis or staphylococci [127-129].

Given concerns regarding achieving adequate tigecycline serum drug concentrations, caution should be used with tigecycline for the treatment of patients with bacteremia [130]. Approved tigecycline dosing is 100 mg IV once, followed by 50 mg IV every 12 hours [131,132]. Major adverse effects include nausea and vomiting. There are reports of higher doses of tigecycline being used for other organisms to improve levels and with prolonged infusion using drug diluted in higher volumes to reduce nausea [133]. Tigecycline is difficult to use for outpatient therapy because of the instability of IV preparations.

Tigecycline may be useful for patients with VRE infection who are intolerant of other agents or when VRE are present along with other pathogens that are susceptible to tigecycline. In addition, tigecycline may also be useful when the biliary system is the source of bacteremia since the drug is eliminated via the hepatobiliary tree. Tigecycline may also be useful in the setting of renal insufficiency. Anecdotal reports have used tigecycline with daptomycin for VRE infections, including endocarditis and meningitis [78,134,135]. In 2010, the FDA issued a boxed warning of increased all-cause mortality in patients receiving tigecycline compared with that of other drugs used to treat a variety of serious infections.

Omadacycline is a new oral tetracycline approved for skin and soft tissue infections (including E. faecalis) and for community-acquired pneumonia. It is available as an oral as well as IV formulation and has in vitro activity against E. faecium that is equal to or slightly less than tigecycline [136,137]. The FDA lists omadacycline MIC breakpoints for E. faecalis only for acute bacterial skin infections, with isolates ≤0.25 mcg/mL considered sensitive, 0.5 mcg/mL intermediate, and ≥1 mcg/mL as resistant. While it might be considered for off-label use as a potential option for VRE infections that are deemed suitable for oral therapy, the only in vivo data indicating efficacy for enterococci was an experimental peritonitis model [138]. Omadacycline is only approximately 30 percent excreted in the urine and this class in general has not performed well in urinary tract infections [139].

Eravacycline is approved for complicated intra-abdominal infections (cIAI) due to susceptible organisms including E. faecalis and E. faecium and is available as an IV formulation. In two randomized controlled trials comparing eravacycline with ertapenem and meropenem, respectively, in treatment of cIAI, similar clinical cure rates were seen in the microbiologic intention to treat population for both E. faecalis (83.3 versus 87 percent) and E. faecium (84.4 versus 90.6 percent) [140,141].

Quinupristin-dalfopristin — Quinupristin-dalfopristin is a mixture of streptogramin antibiotics with in vitro activity against VRE; a previous FDA approval for the treatment of vancomycin-resistant E. faecium infections [142] was subsequently withdrawn. It has poor activity against E. faecalis due to a species-specific adenosine triphosphate (ATP)-binding protein [143,144]. Central venous access requirements and adverse effects limit the use of quinupristin-dalfopristin; these include metabolic interactions, severe myalgias, arthralgias, nausea, and hyperbilirubinemia. (See "Mechanisms of antibiotic resistance in enterococci".)

In a study of 396 patients with VRE infections treated with quinupristin-dalfopristin (including bacteremia, intra-abdominal infections, urinary tract infections, and skin infections), the overall efficacy of quinupristin-dalfopristin (both clinical and bacteriologic success) was 66 percent [145]. Clinical response to quinupristin-dalfopristin is comparable with that of linezolid [146].

Teicoplanin — Teicoplanin is a glycopeptide that is not available in the United States [147]. It has in vitro activity against E. gallinarum and E. casseliflavus (VanC VRE) as well as most VanB-type VRE, although it is rarely active against VanA-type VRE. Some VanB VRE mutant strains are constitutively resistant to teicoplanin and have emerged after drug exposure in vitro and in vivo [148,149]. (See "Mechanisms of antibiotic resistance in enterococci", section on 'Vancomycin resistance'.)

In countries where it is available, teicoplanin may be used for treatment of infections due to susceptible enterococci. For patients with normal renal function, it should be administered with loading doses of 6 mg/kg (12 mg/kg for serious infections) every 12 hours for three doses (up to five doses for serious infections) followed by 6 mg/kg (12 mg/kg for serious infections) every 24 hours. The addition of an aminoglycoside (gentamicin or streptomycin, in the absence of high-level resistance to one of these drugs) should be considered to reduce the emergence of VanB mutants resistant to teicoplanin.

Telavancin — Telavancin is a lipoglycopeptide approved for complicated skin and skin structure infections caused by susceptible gram-positive bacteria, including S. aureus and vancomycin-susceptible E. faecalis. There are no clinical data regarding use of telavancin for other enterococcal infections, but it is about fourfold more potent than vancomycin against enterococci (eg, the MIC for 90 percent of strains [MIC90] is 0.12 mcg/mL), with little to no increase in MICs against VanB strains; for VanA strains, the MIC90 has been reported as 4 to 16 mcg/mL in various studies (versus >256 mcg/mL for vancomycin) [150-152].

Combination therapy — Data on additional therapeutic combinations for treatment of infections due to VRE are limited. Options, depending on susceptibility, include:

Daptomycin with gentamicin (or streptomycin) and/or ampicillin or ceftaroline [87,101,102,153]

Daptomycin plus tigecycline [78,134,135]

Daptomycin, gentamicin, and rifampin [154]

Ampicillin plus quinupristin-dalfopristin [155,156]

Quinupristin-dalfopristin with doxycycline and rifampin [157]

Quinupristin-dalfopristin plus minocycline [158]

Ampicillin plus a fluoroquinolone (ciprofloxacin or ofloxacin) [159]

Alternative agents — Fluoroquinolones may be useful for treatment of enterococcal urinary tract infections in some circumstances. There are several case reports of success with moxifloxacin (usually with amoxicillin given before or after) for enterococcal prostatitis caused by susceptible organisms [160,161]. We would also consider using moxifloxacin plus amoxicillin for enterococcal prostatitis; this combination was one of the step-down regimens for enterococcal endocarditis in the Partial Oral versus Intravenous Antibiotic Treatment of Endocarditis (POET) study. Combination therapy of a fluoroquinolone plus amoxicillin offers a theoretical advantage of decreasing the emergence of fluoroquinolone resistance. Whether concentrations of amoxicillin in the prostate are sufficient to achieve this effect is not known. Tetracycline and chloramphenicol may demonstrate in vitro activity against some strains of enterococci, but they are only bacteriostatic against these organisms [162,163]. Clinical success and failure with chloramphenicol has been described, but the toxicity of this agent limits its usefulness [164-166]. (See 'Urinary tract infection' above.)

Most enterococci in the United States are resistant to erythromycin and other macrolides. In addition, although some enterococcal isolates demonstrate in vitro susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX), testing is not recommended because, in vivo, enterococci can use exogenous folic acid and bypass the block in folate synthesis induced by TMP-SMX [14] and there is a lack of data on clinical efficacy. Therefore, TMP-SMX should not be used for treatment of enterococcal infections, even if in vitro susceptibility testing suggests sensitivity [167-169].

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topic (see "Patient education: Vancomycin-resistant enterococci (The Basics)")

SUMMARY AND RECOMMENDATIONS

Approach to susceptible strains − Enterococci are relatively resistant to the killing effects of cell wall-active agents (penicillin, ampicillin, and vancomycin) and are impermeable to aminoglycosides. Antibiotic regimens and doses for susceptible strains are outlined in the table (table 1). (See 'Approach to susceptible strains' above.)

Approach to resistant strains − The major categories of resistant enterococci include those with high-level penicillin and ampicillin resistance and those with vancomycin resistance. Antibiotic regimens and doses for resistant strains are outlined in the tables (table 2). (See 'Approach to resistant strains' above.)

Approach to specific infections

Urinary tract infection − Options for oral treatment of enterococcal urinary tract infections (UTIs) are outlined in the table (table 3). For patients with lower UTI caused by susceptible strains, we suggest treatment with amoxicillin, fosfomycin, or nitrofurantoin (Grade 2B). For patients Enterococcus faecalis with complicated UTI and for patients unable to tolerate oral therapy, we suggest parenteral ampicillin (Grade 2B). (See 'Urinary tract infection' above.)

Bacteremia

-We recommend antimicrobial therapy for treatment of two or more positive blood cultures, a single positive blood culture accompanied by signs of sepsis, or a single positive blood culture together with a positive enterococcal culture from another usually sterile site (Grade 1B). Options for monotherapy and combination therapy are outlined in the tables (table 2). For uncomplicated infection, five to seven days of therapy is likely adequate. (See 'Bacteremia' above.)

-For treatment of enterococcal bacteremia with suspected endocarditis or critical illness, we recommend combination antimicrobial therapy over monotherapy (Grade 1B). Of the combination antimicrobial regimens, we suggest ampicillin plus ceftriaxone for E. faecalis since it avoids the toxicity of aminoglycosides (Grade 2B); use of a cell wall-active agent in combination with a synergistically active aminoglycoside is also acceptable. (See 'Bacteremia' above.)

Endocarditis − The treatment of enterococcal endocarditis is discussed in detail separately. (See "Antimicrobial therapy of left-sided native valve endocarditis" and "Antimicrobial therapy of prosthetic valve endocarditis".)

Meningitis − For treatment of enterococcal meningitis, we recommend combination antimicrobial therapy over monotherapy (Grade 1C). Of the combination antimicrobial regimens, we suggest ampicillin, ceftriaxone, and gentamicin (table 4) (Grade 2C). (See 'Meningitis' above.)

  1. Baddour LM, Wilson WR, Bayer AS, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A Scientific Statement for Healthcare Professionals From the American Heart Association. Circulation 2015; 132:1435.
  2. Conceição N, da Silva LE, Darini AL, et al. Penicillin-resistant, ampicillin-susceptible Enterococcus faecalis of hospital origin: pbp4 gene polymorphism and genetic diversity. Infect Genet Evol 2014; 28:289.
  3. Ono S, Muratani T, Matsumoto T. Mechanisms of resistance to imipenem and ampicillin in Enterococcus faecalis. Antimicrob Agents Chemother 2005; 49:2954.
  4. Rice LB, Desbonnet C, Tait-Kamradt A, et al. Structural and Regulatory Changes in PBP4 Trigger Decreased β-Lactam Susceptibility in Enterococcus faecalis. mBio 2018; 9.
  5. Fernández-Hidalgo N, Almirante B, Gavaldà J, et al. Ampicillin plus ceftriaxone is as effective as ampicillin plus gentamicin for treating enterococcus faecalis infective endocarditis. Clin Infect Dis 2013; 56:1261.
  6. Caballero-Granado FJ, Cisneros JM, Luque R, et al. Comparative study of bacteremias caused by Enterococcus spp. with and without high-level resistance to gentamicin. The Grupo Andaluz para el estudio de las Enfermedades Infecciosas. J Clin Microbiol 1998; 36:520.
  7. Antalek MD, Mylotte JM, Lesse AJ, Sellick JA Jr. Clinical and molecular epidemiology of Enterococcus faecalis bacteremia, with special reference to strains with high-level resistance to gentamicin. Clin Infect Dis 1995; 20:103.
  8. Choice of antibacterial drugs. Treat Guidel Med Lett 2007; 5:33.
  9. Murray BE. Vancomycin-resistant enterococcal infections. N Engl J Med 2000; 342:710.
  10. Mekonen ET, Noskin GA, Hacek DM, Peterson LR. Successful treatment of persistent bacteremia due to vancomycin-resistant, ampicillin-resistant Enterococcus faecium. Microb Drug Resist 1995; 1:249.
  11. Dodge RA, Daly JS, Davaro R, Glew RH. High-dose ampicillin plus streptomycin for treatment of a patient with severe infection due to multiresistant enterococci. Clin Infect Dis 1997; 25:1269.
  12. Gavaldà J, Torres C, Tenorio C, et al. Efficacy of ampicillin plus ceftriaxone in treatment of experimental endocarditis due to Enterococcus faecalis strains highly resistant to aminoglycosides. Antimicrob Agents Chemother 1999; 43:639.
  13. Gavaldà J, Len O, Miró JM, et al. Brief communication: treatment of Enterococcus faecalis endocarditis with ampicillin plus ceftriaxone. Ann Intern Med 2007; 146:574.
  14. Murray BE. The life and times of the Enterococcus. Clin Microbiol Rev 1990; 3:46.
  15. NNIS System. National Nosocomial Infections Surveillance (NNIS) System Report, Data Summary from January 1990-May 1999, issued June 1999. A report from the NNIS System. Am J Infect Control 1999; 27:520.
  16. National Nosocomial Infections Surveillance (NNIS) System report, data summary from October 1986-April 1998, issued June 1998. Am J Infect Control 1998; 26:522.
  17. Jones RN, Kugler KC, Pfaller MA, Winokur PL. Characteristics of pathogens causing urinary tract infections in hospitals in North America: results from the SENTRY Antimicrobial Surveillance Program, 1997. Diagn Microbiol Infect Dis 1999; 35:55.
  18. Hooton TM, Roberts PL, Cox ME, Stapleton AE. Voided midstream urine culture and acute cystitis in premenopausal women. N Engl J Med 2013; 369:1883.
  19. Krieger JN, Kaiser DL, Wenzel RP. Urinary tract etiology of bloodstream infections in hospitalized patients. J Infect Dis 1983; 148:57.
  20. Lai KK. Treatment of vancomycin-resistant Enterococcus faecium infections. Arch Intern Med 1996; 156:2579.
  21. Minassian MA, Lewis DA, Chattopadhyay D, et al. A comparison between single-dose fosfomycin trometamol (Monuril) and a 5-day course of trimethoprim in the treatment of uncomplicated lower urinary tract infection in women. Int J Antimicrob Agents 1998; 10:39.
  22. Patel SS, Balfour JA, Bryson HM. Fosfomycin tromethamine. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy as a single-dose oral treatment for acute uncomplicated lower urinary tract infections. Drugs 1997; 53:637.
  23. Allerberger F, Klare I. In-vitro activity of fosfomycin against vancomycin-resistant enterococci. J Antimicrob Chemother 1999; 43:211.
  24. Onrust SV, Lamb HM, Balfour JA. Ofloxacin. A reappraisal of its use in the management of genitourinary tract infections. Drugs 1998; 56:895.
  25. Malinverni R, Glauser MP. Comparative studies of fluoroquinolones in the treatment of urinary tract infections. Rev Infect Dis 1988; 10 Suppl 1:S153.
  26. Corrado ML, Hesney M, Struble WE, et al. Norfloxacin versus trimethoprim-sulfamethoxazole in the treatment of urinary tract infections. Eur Urol 1990; 17 Suppl 1:34.
  27. Zervos MJ, Bacon AE 3rd, Patterson JE, et al. Enterococcal superinfection in patients treated with ciprofloxacin. J Antimicrob Chemother 1988; 21:113.
  28. Tice AD. Short-course therapy of acute cystitis: a brief review of therapeutic strategies. J Antimicrob Chemother 1999; 43 Suppl A:85.
  29. Stannard AJ, Sharples SJ, Norman PM, Tillotson GS. Ciprofloxacin therapy of urinary tract infections in paraplegic and tetraplegic patients: a bacteriological assessment. J Antimicrob Chemother 1990; 26 Suppl F:13.
  30. Malathum K, Singh KV, Murray BE. In vitro activity of moxifloxacin, a new 8-methoxyquinolone, against gram-positive bacteria. Diagn Microbiol Infect Dis 1999; 35:127.
  31. Coque TM, Singh KV, Murray BE. Comparative in-vitro activity of the new fluoroquinolone trovafloxacin (CP-99,219) against gram-positive cocci. J Antimicrob Chemother 1996; 37:1011.
  32. Martínez-Martínez L, Joyanes P, Pascual A, et al. Activity of eight fluoroquinolones against enterococci. Clin Microbiol Infect 1997; 3:497.
  33. Cole M, Ridley B. Absence of bioactive metabolites of ampicillin and amoxycillin in man. J Antimicrob Chemother 1978; 4:580.
  34. Cole KA, Kenney RM, Perri MB, et al. Outcomes of Aminopenicillin Therapy for Vancomycin-Resistant Enterococcal Urinary Tract Infections. Antimicrob Agents Chemother 2015; 59:7362.
  35. Shah KJ, Cherabuddi K, Shultz J, et al. Ampicillin for the treatment of complicated urinary tract infections caused by vancomycin-resistant Enterococcus spp (VRE): a single-center university hospital experience. Int J Antimicrob Agents 2018; 51:57.
  36. Gray J, Marsh PJ, Stewart D, Pedler SJ. Enterococcal bacteraemia: a prospective study of 125 episodes. J Hosp Infect 1994; 27:179.
  37. Maki DG, Agger WA. Enterococcal bacteremia: clinical features, the risk of endocarditis, and management. Medicine (Baltimore) 1988; 67:248.
  38. Patterson JE, Sweeney AH, Simms M, et al. An analysis of 110 serious enterococcal infections. Epidemiology, antibiotic susceptibility, and outcome. Medicine (Baltimore) 1995; 74:191.
  39. Graninger W, Ragette R. Nosocomial bacteremia due to Enterococcus faecalis without endocarditis. Clin Infect Dis 1992; 15:49.
  40. Shlaes DM, Levy J, Wolinsky E. Enterococcal bacteremia without endocarditis. Arch Intern Med 1981; 141:578.
  41. Gullberg RM, Homann SR, Phair JP. Enterococcal bacteremia: analysis of 75 episodes. Rev Infect Dis 1989; 11:74.
  42. Hoge CW, Adams J, Buchanan B, Sears SD. Enterococcal bacteremia: to treat or not to treat, a reappraisal. Rev Infect Dis 1991; 13:600.
  43. Weinstein MP, Towns ML, Quartey SM, et al. The clinical significance of positive blood cultures in the 1990s: a prospective comprehensive evaluation of the microbiology, epidemiology, and outcome of bacteremia and fungemia in adults. Clin Infect Dis 1997; 24:584.
  44. Edmond MB, Wallace SE, McClish DK, et al. Nosocomial bloodstream infections in United States hospitals: a three-year analysis. Clin Infect Dis 1999; 29:239.
  45. Wisplinghoff H, Bischoff T, Tallent SM, et al. Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. Clin Infect Dis 2004; 39:309.
  46. Anderson DJ, Murdoch DR, Sexton DJ, et al. Risk factors for infective endocarditis in patients with enterococcal bacteremia: a case-control study. Infection 2004; 32:72.
  47. Berge A, Krantz A, Östlund H, et al. The DENOVA score efficiently identifies patients with monomicrobial Enterococcus faecalis bacteremia where echocardiography is not necessary. Infection 2019; 47:45.
  48. Watanakunakorn C, Patel R. Comparison of patients with enterococcal bacteremia due to strains with and without high-level resistance to gentamicin. Clin Infect Dis 1993; 17:74.
  49. Britt NS, Potter EM, Patel N, Steed ME. Comparative Effectiveness and Safety of Standard-, Medium-, and High-Dose Daptomycin Strategies for the Treatment of Vancomycin-Resistant Enterococcal Bacteremia Among Veterans Affairs Patients. Clin Infect Dis 2017; 64:605.
  50. Beganovic M, Luther MK, Rice LB, et al. A Review of Combination Antimicrobial Therapy for Enterococcus faecalis Bloodstream Infections and Infective Endocarditis. Clin Infect Dis 2018; 67:303.
  51. Lorenzo MP, Kidd JM, Jenkins SG, et al. In vitro activity of ampicillin and ceftriaxone against ampicillin-susceptible Enterococcus faecium. J Antimicrob Chemother 2019; 74:2269.
  52. Munita JM, Murray BE, Arias CA. Daptomycin for the treatment of bacteraemia due to vancomycin-resistant enterococci. Int J Antimicrob Agents 2014; 44:387.
  53. Balli EP, Venetis CA, Miyakis S. Systematic review and meta-analysis of linezolid versus daptomycin for treatment of vancomycin-resistant enterococcal bacteremia. Antimicrob Agents Chemother 2014; 58:734.
  54. Whang DW, Miller LG, Partain NM, McKinnell JA. Systematic review and meta-analysis of linezolid and daptomycin for treatment of vancomycin-resistant enterococcal bloodstream infections. Antimicrob Agents Chemother 2013; 57:5013.
  55. Chuang YC, Wang JT, Lin HY, Chang SC. Daptomycin versus linezolid for treatment of vancomycin-resistant enterococcal bacteremia: systematic review and meta-analysis. BMC Infect Dis 2014; 14:687.
  56. Britt NS, Potter EM, Patel N, Steed ME. Comparison of the Effectiveness and Safety of Linezolid and Daptomycin in Vancomycin-Resistant Enterococcal Bloodstream Infection: A National Cohort Study of Veterans Affairs Patients. Clin Infect Dis 2015; 61:871.
  57. Pericàs JM, Corredoira J, Moreno A, et al. Relationship Between Enterococcus faecalis Infective Endocarditis and Colorectal Neoplasm: Preliminary Results From a Cohort of 154 Patients. Rev Esp Cardiol (Engl Ed) 2017; 70:451.
  58. Pericàs JM, Ambrosioni J, Muñoz P, et al. Prevalence of Colorectal Neoplasms Among Patients With Enterococcus faecalis Endocarditis in the GAMES Cohort (2008-2017). Mayo Clin Proc 2021; 96:132.
  59. Stevenson KB, Murray EW, Sarubbi FA. Enterococcal meningitis: report of four cases and review. Clin Infect Dis 1994; 18:233.
  60. Bayer AS, Seidel JS, Yoshikawa TT, et al. Group D enterococcal meningitis. Clinical and therapeutic considerations with report of three cases and review of the literature. Arch Intern Med 1976; 136:883.
  61. Kurup A, Tee WS, Loo LH, Lin R. Infection of central nervous system by motile Enterococcus: first case report. J Clin Microbiol 2001; 39:820.
  62. Buchino JJ, Ciambarella E, Light I. Systemic group D streptococcal infection in newborn infants. Am J Dis Child 1979; 133:270.
  63. Siegel JD, McCracken GH Jr. Group D streptococcal infections. J Pediatr 1978; 93:542.
  64. Nagai K, Yuge K, Ono E, et al. Enterococcus faecium meningitis in a child. Pediatr Infect Dis J 1994; 13:1016.
  65. Elvy J, Porter D, Brown E. Treatment of external ventricular drain-associated ventriculitis caused by Enterococcus faecalis with intraventricular daptomycin. J Antimicrob Chemother 2008; 61:461.
  66. Williamson JC, Glazier SS, Peacock JE Jr. Successful treatment of ventriculostomy-related meningitis caused by vancomycin-resistant Enterococcus with intravenous and intraventricular quinupristin/dalfopristin. Clin Neurol Neurosurg 2002; 104:54.
  67. Nachman SA, Verma R, Egnor M. Vancomycin-resistant Enterococcus faecium shunt infection in an infant: an antibiotic cure. Microb Drug Resist 1995; 1:95.
  68. Tush GM, Huneycutt S, Phillips A, Ward JD. Intraventricular quinupristin/dalfopristin for the treatment of vancomycin-resistant Enterococcus faecium shunt infection. Clin Infect Dis 1998; 26:1460.
  69. Garey KW, Tesoro E, Muggia V, et al. Cerebrospinal fluid concentrations of quinupristin-dalfopristin in a patient with vancomycin-resistant Enterococcus faecium [correction of faecalis] ventriculitis. Pharmacotherapy 2001; 21:748.
  70. Shaikh ZH, Peloquin CA, Ericsson CD. Successful treatment of vancomycin-resistant Enterococcus faecium meningitis with linezolid: case report and literature review. Scand J Infect Dis 2001; 33:375.
  71. Zeana C, Kubin CJ, Della-Latta P, Hammer SM. Vancomycin-resistant Enterococcus faecium meningitis successfully managed with linezolid: case report and review of the literature. Clin Infect Dis 2001; 33:477.
  72. Graham PL, Ampofo K, Saiman L. Linezolid treatment of vancomycin-resistant Enterococcus faecium ventriculitis. Pediatr Infect Dis J 2002; 21:798.
  73. Hachem R, Afif C, Gokaslan Z, Raad I. Successful treatment of vancomycin-resistant Enterococcus meningitis with linezolid. Eur J Clin Microbiol Infect Dis 2001; 20:432.
  74. Steinmetz MP, Vogelbaum MA, De Georgia MA, et al. Successful treatment of vancomycin-resistant enterococcus meningitis with linezolid: case report and review of the literature. Crit Care Med 2001; 29:2383.
  75. Wang JS, Muzevich K, Edmond MB, et al. Central nervous system infections due to vancomycin-resistant enterococci: case series and review of the literature. Int J Infect Dis 2014; 25:26.
  76. Knoll BM, Hellmann M, Kotton CN. Vancomycin-resistant Enterococcus faecium meningitis in adults: case series and review of the literature. Scand J Infect Dis 2013; 45:131.
  77. Le J, Bookstaver PB, Rudisill CN, et al. Treatment of meningitis caused by vancomycin-resistant Enterococcus faecium: high-dose and combination daptomycin therapy. Ann Pharmacother 2010; 44:2001.
  78. Jaspan HB, Brothers AW, Campbell AJ, et al. Multidrug-resistant Enterococcus faecium meningitis in a toddler: characterization of the organism and successful treatment with intraventricular daptomycin and intravenous tigecycline. Pediatr Infect Dis J 2010; 29:379.
  79. Ryan JL, Pachner A, Andriole VT, Root RK. Enterococcal meningitis: combined vancomycin and rifampin therapy. Am J Med 1980; 68:449.
  80. Pérez Mato S, Robinson S, Bégué RE. Vancomycin-resistant Enterococcus faecium meningitis successfully treated with chloramphenicol. Pediatr Infect Dis J 1999; 18:483.
  81. Venezio FR, Masters D, O'Keefe P. Enterococcal meningitis: failure of treatment with ampicillin and chloramphenicol. J Infect Dis 1984; 150:305.
  82. Şahin A, Dalgic N. Intraventricular Plus Intravenous Tigecycline for the Treatment of Daptomycin Nonsusceptible Vancomycin-Resistant Enterococci in an Infant with Ventriculoperitoneal Shunt Infection. World Neurosurg 2019; 130:470.
  83. Tunkel AR, Hasbun R, Bhimraj A, et al. 2017 Infectious Diseases Society of America's Clinical Practice Guidelines for Healthcare-Associated Ventriculitis and Meningitis. Clin Infect Dis 2017.
  84. Wilson DN, Schluenzen F, Harms JM, et al. The oxazolidinone antibiotics perturb the ribosomal peptidyl-transferase center and effect tRNA positioning. Proc Natl Acad Sci U S A 2008; 105:13339.
  85. Long KS, Poehlsgaard J, Kehrenberg C, et al. The Cfr rRNA methyltransferase confers resistance to Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics. Antimicrob Agents Chemother 2006; 50:2500.
  86. Toh SM, Xiong L, Arias CA, et al. Acquisition of a natural resistance gene renders a clinical strain of methicillin-resistant Staphylococcus aureus resistant to the synthetic antibiotic linezolid. Mol Microbiol 2007; 64:1506.
  87. Arias CA, Torres HA, Singh KV, et al. Failure of daptomycin monotherapy for endocarditis caused by an Enterococcus faecium strain with vancomycin-resistant and vancomycin-susceptible subpopulations and evidence of in vivo loss of the vanA gene cluster. Clin Infect Dis 2007; 45:1343.
  88. Wang Y, Lv Y, Cai J, et al. A novel gene, optrA, that confers transferable resistance to oxazolidinones and phenicols and its presence in Enterococcus faecalis and Enterococcus faecium of human and animal origin. J Antimicrob Chemother 2015; 70:2182.
  89. Antonelli A, D'Andrea MM, Brenciani A, et al. Characterization of poxtA, a novel phenicol-oxazolidinone-tetracycline resistance gene from an MRSA of clinical origin. J Antimicrob Chemother 2018; 73:1763.
  90. Birmingham MC, Rayner CR, Meagher AK, et al. Linezolid for the treatment of multidrug-resistant, gram-positive infections: experience from a compassionate-use program. Clin Infect Dis 2003; 36:159.
  91. El-Khoury J, Fishman JA. Linezolid in the treatment of vancomycin-resistant Enterococcus faecium in solid organ transplant recipients: report of a multicenter compassionate-use trial. Transpl Infect Dis 2003; 5:121.
  92. Zimmer SM, Caliendo AM, Thigpen MC, Somani J. Failure of linezolid treatment for enterococcal endocarditis. Clin Infect Dis 2003; 37:e29.
  93. Meka VG, Gold HS. Antimicrobial resistance to linezolid. Clin Infect Dis 2004; 39:1010.
  94. Lawrence KR, Adra M, Gillman PK. Serotonin toxicity associated with the use of linezolid: a review of postmarketing data. Clin Infect Dis 2006; 42:1578.
  95. Taylor JJ, Wilson JW, Estes LL. Linezolid and serotonergic drug interactions: a retrospective survey. Clin Infect Dis 2006; 43:180.
  96. Wu VC, Wang YT, Wang CY, et al. High frequency of linezolid-associated thrombocytopenia and anemia among patients with end-stage renal disease. Clin Infect Dis 2006; 42:66.
  97. Senneville E, Legout L, Valette M, et al. Effectiveness and tolerability of prolonged linezolid treatment for chronic osteomyelitis: a retrospective study. Clin Ther 2006; 28:1155.
  98. Palenzuela L, Hahn NM, Nelson RP Jr, et al. Does linezolid cause lactic acidosis by inhibiting mitochondrial protein synthesis? Clin Infect Dis 2005; 40:e113.
  99. Rucker JC, Hamilton SR, Bardenstein D, et al. Linezolid-associated toxic optic neuropathy. Neurology 2006; 66:595.
  100. Boucher HW, Sakoulas G. Perspectives on Daptomycin resistance, with emphasis on resistance in Staphylococcus aureus. Clin Infect Dis 2007; 45:601.
  101. Sakoulas G, Rose W, Nonejuie P, et al. Ceftaroline restores daptomycin activity against daptomycin-nonsusceptible vancomycin-resistant Enterococcus faecium. Antimicrob Agents Chemother 2014; 58:1494.
  102. Sakoulas G, Bayer AS, Pogliano J, et al. Ampicillin enhances daptomycin- and cationic host defense peptide-mediated killing of ampicillin- and vancomycin-resistant Enterococcus faecium. Antimicrob Agents Chemother 2012; 56:838.
  103. Sierra-Hoffman M, Iznaola O, Goodwin M, Mohr J. Combination therapy with ampicillin and daptomycin for treatment of Enterococcus faecalis endocarditis. Antimicrob Agents Chemother 2012; 56:6064.
  104. Diaz L, Tran TT, Munita JM, et al. Whole-genome analyses of Enterococcus faecium isolates with diverse daptomycin MICs. Antimicrob Agents Chemother 2014; 58:4527.
  105. Hindler JA, Wong-Beringer A, Charlton CL, et al. In vitro activity of daptomycin in combination with β-lactams, gentamicin, rifampin, and tigecycline against daptomycin-nonsusceptible enterococci. Antimicrob Agents Chemother 2015; 59:4279.
  106. Safdar N, Andes D, Craig WA. In vivo pharmacodynamic activity of daptomycin. Antimicrob Agents Chemother 2004; 48:63.
  107. Vouillamoz J, Moreillon P, Giddey M, Entenza JM. Efficacy of daptomycin in the treatment of experimental endocarditis due to susceptible and multidrug-resistant enterococci. J Antimicrob Chemother 2006; 58:1208.
  108. Caron F, Kitzis MD, Gutmann L, et al. Daptomycin or teicoplanin in combination with gentamicin for treatment of experimental endocarditis due to a highly glycopeptide-resistant isolate of Enterococcus faecium. Antimicrob Agents Chemother 1992; 36:2611.
  109. Munita JM, Mishra NN, Alvarez D, et al. Failure of high-dose daptomycin for bacteremia caused by daptomycin-susceptible Enterococcus faecium harboring LiaSR substitutions. Clin Infect Dis 2014; 59:1277.
  110. Munita JM, Tran TT, Diaz L, et al. A liaF codon deletion abolishes daptomycin bactericidal activity against vancomycin-resistant Enterococcus faecalis. Antimicrob Agents Chemother 2013; 57:2831.
  111. Munita JM, Panesso D, Diaz L, et al. Correlation between mutations in liaFSR of Enterococcus faecium and MIC of daptomycin: revisiting daptomycin breakpoints. Antimicrob Agents Chemother 2012; 56:4354.
  112. Shukla BS, Shelburne S, Reyes K, et al. Influence of Minimum Inhibitory Concentration in Clinical Outcomes of Enterococcus faecium Bacteremia Treated With Daptomycin: Is it Time to Change the Breakpoint? Clin Infect Dis 2016; 62:1514.
  113. Nigo M, Munita JM, Arias CA, Murray BE. What's New in the Treatment of Enterococcal Endocarditis? Curr Infect Dis Rep 2014; 16:431.
  114. Avery LM, Kuti JL, Weisser M, et al. Pharmacodynamic Analysis of Daptomycin-treated Enterococcal Bacteremia: It Is Time to Change the Breakpoint. Clin Infect Dis 2019; 68:1650.
  115. Avery LM, Kuti JL, Weisser M, et al. Pharmacodynamics of daptomycin in combination with other antibiotics for the treatment of enterococcal bacteraemia. Int J Antimicrob Agents 2019; 54:346.
  116. Chuang YC, Lin HY, Chen PY, et al. Effect of Daptomycin Dose on the Outcome of Vancomycin-Resistant, Daptomycin-Susceptible Enterococcus faecium Bacteremia. Clin Infect Dis 2017; 64:1026.
  117. Chuang YC, Lin HY, Yang JL, et al. Influence of daptomycin doses on the outcomes of VRE bloodstream infection treated with high-dose daptomycin. J Antimicrob Chemother 2022; 77:2278.
  118. Chuang YC, Chen PY, Lin CY, et al. A retrospective clinical comparison of daptomycin vs daptomycin and a beta-lactam antibiotic for treating vancomycin-resistant Enterococcus faecium bloodstream infections. Sci Rep 2018; 8:1632.
  119. Skiest DJ. Treatment failure resulting from resistance of Staphylococcus aureus to daptomycin. J Clin Microbiol 2006; 44:655.
  120. Humphries RM, Abbott AN, Hindler JA. Understanding and Addressing CLSI Breakpoint Revisions: a Primer for Clinical Laboratories. J Clin Microbiol 2019; 57.
  121. Campeau SA, Schuetz AN, Kohner P, et al. Variability of Daptomycin MIC Values for Enterococcus faecium When Measured by Reference Broth Microdilution and Gradient Diffusion Tests. Antimicrob Agents Chemother 2018; 62.
  122. Allen NE, Nicas TI. Mechanism of action of oritavancin and related glycopeptide antibiotics. FEMS Microbiol Rev 2003; 26:511.
  123. Ward KE, Mersfelder TL, LaPlante KL. Oritavancin--an investigational glycopeptide antibiotic. Expert Opin Investig Drugs 2006; 15:417.
  124. Corey GR, Kabler H, Mehra P, et al. Single-dose oritavancin in the treatment of acute bacterial skin infections. N Engl J Med 2014; 370:2180.
  125. Johnson JA, Feeney ER, Kubiak DW, Corey GR. Prolonged Use of Oritavancin for Vancomycin-Resistant Enterococcus faecium Prosthetic Valve Endocarditis. Open Forum Infect Dis 2015; 2:ofv156.
  126. US Food and Drug Administration. FDA approves Orbactiv to treat skin infections. http://www.fda.gov/newsevents/newsroom/pressannouncements/ucm408475.htm (Accessed on August 07, 2014).
  127. Waites KB, Duffy LB, Dowzicky MJ. Antimicrobial susceptibility among pathogens collected from hospitalized patients in the United States and in vitro activity of tigecycline, a new glycylcycline antimicrobial. Antimicrob Agents Chemother 2006; 50:3479.
  128. Lefort A, Lafaurie M, Massias L, et al. Activity and diffusion of tigecycline (GAR-936) in experimental enterococcal endocarditis. Antimicrob Agents Chemother 2003; 47:216.
  129. Murphy TM, Deitz JM, Petersen PJ, et al. Therapeutic efficacy of GAR-936, a novel glycylcycline, in a rat model of experimental endocarditis. Antimicrob Agents Chemother 2000; 44:3022.
  130. Rodvold KA, Gotfried MH, Cwik M, et al. Serum, tissue and body fluid concentrations of tigecycline after a single 100 mg dose. J Antimicrob Chemother 2006; 58:1221.
  131. Ellis-Grosse EJ, Babinchak T, Dartois N, et al. The efficacy and safety of tigecycline in the treatment of skin and skin-structure infections: results of 2 double-blind phase 3 comparison studies with vancomycin-aztreonam. Clin Infect Dis 2005; 41 Suppl 5:S341.
  132. Postier RG, Green SL, Klein SR, et al. Results of a multicenter, randomized, open-label efficacy and safety study of two doses of tigecycline for complicated skin and skin-structure infections in hospitalized patients. Clin Ther 2004; 26:704.
  133. Falagas ME, Vardakas KZ, Tsiveriotis KP, et al. Effectiveness and safety of high-dose tigecycline-containing regimens for the treatment of severe bacterial infections. Int J Antimicrob Agents 2014; 44:1.
  134. Jenkins I. Linezolid- and vancomycin-resistant Enterococcus faecium endocarditis: successful treatment with tigecycline and daptomycin. J Hosp Med 2007; 2:343.
  135. Schutt AC, Bohm NM. Multidrug-resistant Enterococcus faecium endocarditis treated with combination tigecycline and high-dose daptomycin. Ann Pharmacother 2009; 43:2108.
  136. Tsai HY, Lee YL, Liu PY, et al. Antimicrobial susceptibility of bacteremic vancomycin-resistant Enterococcus faecium to eravacycline, omadacycline, lipoglycopeptides, and other comparator antibiotics: Results from the 2019-2020 Nationwide Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART). Int J Antimicrob Agents 2021; 58:106353.
  137. Liu X, Zhang C, Zhao Y, et al. Comparison of antibacterial activities and resistance mechanisms of omadacycline and tigecycline against Enterococcus faecium. J Antibiot (Tokyo) 2022; 75:463.
  138. Singh KV, Arias CA, Murray BE. Efficacy of Omadacycline against Multidrug-Resistant Enterococcus faecium Strains in a Mouse Peritonitis Model. Antimicrob Agents Chemother 2021; 65:e0070921.
  139. Overcash JS, Bhiwandi P, Garrity-Ryan L, et al. Pharmacokinetics, Safety, and Clinical Outcomes of Omadacycline in Women with Cystitis: Results from a Phase 1b Study. Antimicrob Agents Chemother 2019; 63.
  140. Solomkin J, Evans D, Slepavicius A, et al. Assessing the Efficacy and Safety of Eravacycline vs Ertapenem in Complicated Intra-abdominal Infections in the Investigating Gram-Negative Infections Treated With Eravacycline (IGNITE 1) Trial: A Randomized Clinical Trial. JAMA Surg 2017; 152:224.
  141. Solomkin JS, Gardovskis J, Lawrence K, et al. IGNITE4: Results of a Phase 3, Randomized, Multicenter, Prospective Trial of Eravacycline vs Meropenem in the Treatment of Complicated Intraabdominal Infections. Clin Infect Dis 2019; 69:921.
  142. Batts DH, Lavin BS, Eliopoulos GM. Quinupristin/dalfopristin and linezolid: spectrum of activity and potential roles in therapy--a status report. Curr Clin Top Infect Dis 2001; 21:227.
  143. Collins LA, Malanoski GJ, Eliopoulos GM, et al. In vitro activity of RP59500, an injectable streptogramin antibiotic, against vancomycin-resistant gram-positive organisms. Antimicrob Agents Chemother 1993; 37:598.
  144. Singh KV, Weinstock GM, Murray BE. An Enterococcus faecalis ABC homologue (Lsa) is required for the resistance of this species to clindamycin and quinupristin-dalfopristin. Antimicrob Agents Chemother 2002; 46:1845.
  145. Moellering RC, Linden PK, Reinhardt J, et al. The efficacy and safety of quinupristin/dalfopristin for the treatment of infections caused by vancomycin-resistant Enterococcus faecium. Synercid Emergency-Use Study Group. J Antimicrob Chemother 1999; 44:251.
  146. Raad I, Hachem R, Hanna H, et al. Prospective, randomized study comparing quinupristin-dalfopristin with linezolid in the treatment of vancomycin-resistant Enterococcus faecium infections. J Antimicrob Chemother 2004; 53:646.
  147. Finch RG, Eliopoulos GM. Safety and efficacy of glycopeptide antibiotics. J Antimicrob Chemother 2005; 55 Suppl 2:ii5.
  148. Baptista M, Depardieu F, Reynolds P, et al. Mutations leading to increased levels of resistance to glycopeptide antibiotics in VanB-type enterococci. Mol Microbiol 1997; 25:93.
  149. Kawalec M, Gniadkowski M, Kedzierska J, et al. Selection of a teicoplanin-resistant Enterococcus faecium mutant during an outbreak caused by vancomycin-resistant enterococci with the vanB phenotype. J Clin Microbiol 2001; 39:4274.
  150. Bérenger R, Bourdon N, Auzou M, et al. In vitro activity of new antimicrobial agents against glycopeptide-resistant Enterococcus faecium clinical isolates from France between 2006 and 2008. Med Mal Infect 2011; 41:405.
  151. Draghi DC, Benton BM, Krause KM, et al. In vitro activity of telavancin against recent Gram-positive clinical isolates: results of the 2004-05 Prospective European Surveillance Initiative. J Antimicrob Chemother 2008; 62:116.
  152. Krause KM, Renelli M, Difuntorum S, et al. In vitro activity of telavancin against resistant gram-positive bacteria. Antimicrob Agents Chemother 2008; 52:2647.
  153. Entenza JM, Giddey M, Vouillamoz J, Moreillon P. In vitro prevention of the emergence of daptomycin resistance in Staphylococcus aureus and enterococci following combination with amoxicillin/clavulanic acid or ampicillin. Int J Antimicrob Agents 2010; 35:451.
  154. Stevens MP, Edmond MB. Endocarditis due to vancomycin-resistant enterococci: case report and review of the literature. Clin Infect Dis 2005; 41:1134.
  155. Thompson RL, Lavin B, Talbot GH. Endocarditis due to vancomycin-resistant Enterococcus faecium in an immunocompromised patient: cure by administering combination therapy with quinupristin/dalfopristin and high-dose ampicillin. South Med J 2003; 96:818.
  156. Bethea JA, Walko CM, Targos PA. Treatment of vancomycin-resistant enterococcus with quinupristin/dalfopristin and high-dose ampicillin. Ann Pharmacother 2004; 38:989.
  157. Matsumura S, Simor AE. Treatment of endocarditis due to vancomycin-resistant Enterococcus faecium with quinupristin/dalfopristin, doxycycline, and rifampin: a synergistic drug combination. Clin Infect Dis 1998; 27:1554.
  158. Raad I, Hachem R, Hanna H, et al. Treatment of vancomycin-resistant enterococcal infections in the immunocompromised host: quinupristin-dalfopristin in combination with minocycline. Antimicrob Agents Chemother 2001; 45:3202.
  159. Tripodi MF, Locatelli A, Adinolfi LE, et al. Successful treatment with ampicillin and fluoroquinolones of human endocarditis due to high-level gentamicin-resistant enterococci. Eur J Clin Microbiol Infect Dis 1998; 17:734.
  160. Pilmis B, Lécuyer H, Lortholary O, Charlier C. Enterococcus faecalis-related prostatitis successfully treated with moxifloxacin. Antimicrob Agents Chemother 2015; 59:7156.
  161. van Nieuwkoop C, Visser LG, Groeneveld JH, Kuijper EJ. Chronic bacterial prostatitis and relapsing Enterococcus faecalis bacteraemia successfully treated with moxifloxacin. J Infect 2008; 56:155.
  162. Moreno F, Jorgensen JH, Weiner MH. An old antibiotic for a new multiple-resistant Enterococcus faecium? Diagn Microbiol Infect Dis 1994; 20:41.
  163. Howe RA, Robson M, Oakhill A, et al. Successful use of tetracycline as therapy of an immunocompromised patient with septicaemia caused by a vancomycin-resistant enterococcus. J Antimicrob Chemother 1997; 40:144.
  164. Lautenbach E, Schuster MG, Bilker WB, Brennan PJ. The role of chloramphenicol in the treatment of bloodstream infection due to vancomycin-resistant Enterococcus. Clin Infect Dis 1998; 27:1259.
  165. Norris AH, Reilly JP, Edelstein PH, et al. Chloramphenicol for the treatment of vancomycin-resistant enterococcal infections. Clin Infect Dis 1995; 20:1137.
  166. Papanicolaou GA, Meyers BR, Meyers J, et al. Nosocomial infections with vancomycin-resistant Enterococcus faecium in liver transplant recipients: risk factors for acquisition and mortality. Clin Infect Dis 1996; 23:760.
  167. Hamilton-Miller JM. Reversal of activity of trimethoprim against gram-positive cocci by thymidine, thymine and 'folates'. J Antimicrob Chemother 1988; 22:35.
  168. Grayson ML, Thauvin-Eliopoulos C, Eliopoulos GM, et al. Failure of trimethoprim-sulfamethoxazole therapy in experimental enterococcal endocarditis. Antimicrob Agents Chemother 1990; 34:1792.
  169. Goodhart GL. In vivo v in vitro susceptibility of enterococcus to trimethoprim-sulfamethoxazole. A pitfall. JAMA 1984; 252:2748.
Topic 3163 Version 48.0

References

آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟