Causes of infection in long-term care facilities: An overview

INTRODUCTION — Long-term care facilities (LTCFs) represent a diverse group of health care settings that serve individuals of all ages and provide variable degrees of care. LTCFs include nursing homes, skilled-nursing facilities providing postacute care, assisted living facilities, retirement homes, rehabilitation centers, long-term care hospitals, long-term psychiatric facilities, and institutions for individuals with intellectual disabilities. For many residents, these facilities are a home as well as a place of nursing, medical, and/or psychosocial care.

This topic will provide an overview of important infections and pathogens seen in LTCFs. LTCFs provide a unique environment for transmission of infection, so they require specific attention to infection control. [1-4]. The principles related to infection control in LTCFs are discussed elsewhere. (See "Principles of infection control in long-term care facilities".)

Topic reviews specific to coronavirus disease 2019 (COVID-19) are presented separately. (See "COVID-19: Epidemiology, virology, and prevention" and "COVID-19: Clinical features" and "COVID-19: Diagnosis" and "COVID-19: Infection prevention for persons with SARS-CoV-2 infection".)

TYPES OF INFECTIONS

Overview — Important types of infection in LTCFs include respiratory tract infection, gastrointestinal infection, urinary tract infection, and skin and soft tissue infection [5]. Together, these infections represent 94 percent of infections seen in LTCFs [2,3,6,7].

Recognition of infections in older adults can be hampered due to physiologic, clinical, and environmental factors such as age-related immune and organ-specific changes, altered temperature regulation, cognitive decline, malnutrition, and inadequate personnel and equipment resources [8,9].

Adverse clinical outcomes associated with infections, including high rates of morbidity and mortality, prolonged hospitalizations, and substantial healthcare costs are frequently reported [9].

Respiratory tract infection — Respiratory infections in LTCFs are common. In some cases, they are due to spread within the facility (eg, influenza), and in other cases they are sporadic in nature (eg, bacterial pneumonia) [10,11].

Influenza — Seasonal outbreaks of influenza affecting LTCF residents and staff are common and are associated with substantial morbidity. The challenges of preventing and controlling influenza outbreaks in these settings are well recognized. In a review of 49 outbreaks, median attack rates were 33 percent in residents and 23 percent in staff [12-14]. Older adults may have less typical presentations of influenza, and this limits the opportunities for early recognition and treatment [15]. In addition, increased age is a recognized risk factor for serious infection [14]. Case attack rates may be up to 70 percent, and case fatality rates may be more than 10 percent [15]. (See "Seasonal influenza in adults: Clinical manifestations and diagnosis", section on 'Uncomplicated illness'.)

Annual influenza vaccination for LTCF residents and staff and residents is important for minimizing risk of infection; all residents and staff should be vaccinated [16]. Influenza vaccine and administration of antiviral prophylaxis in outbreak settings are discussed in detail separately. (See "Principles of infection control in long-term care facilities", section on 'Prevention of infection' and "Seasonal influenza in nonpregnant adults: Treatment" and "Seasonal influenza in adults: Role of antiviral prophylaxis for prevention".)

Pneumonia — Mortality due to pneumonia is higher among residents of LTCFs than adults in the community. In addition, an episode of pneumonia in a LTCF resident is associated with increased morbidity that persists for up to two years [17]. Predisposing factors include underlying obstructive pulmonary disease, left heart failure, and risk of aspiration [18,19]. Aspiration pneumonia is common in the presence of risk factors including stroke, neuromuscular disorders, or impaired consciousness.

Pneumonia in LTCFs may be caused by pathogens associated with community-acquired pneumonia or hospital-acquired pneumonia. The microbiology depends on whether residents have recently been in an acute care facility and their length of stay in the LTCF. Streptococcus pneumoniae is the most common pathogen [20,21]. Improving pneumococcal vaccination rates is a goal for all adults in LTCFs [22]. (See "Pneumococcal vaccination in adults", section on 'Vaccine selection' and "Principles of infection control in long-term care facilities", section on 'Prevention of infection'.)

Gram-negative bacilli are also an important cause of pneumonia in LTCFs [20,23-25]. One study noted a colonization rate of 51 percent; the isolates included Providencia stuartii, Morganella morganii, Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, and Enterobacter spp [6]. Risk factors for colonization included dementia and nonambulatory status. Risk factors for pneumonia due to drug-resistant pathogens include antibiotic exposure in the past six months, chronic ventilation, and low Activities of Daily Living score.

Atypical pathogens such as Mycoplasma pneumoniae are less common in LTCFs than in the general community [20].

Rhinovirus — Rhinovirus is a common cause of respiratory outbreaks in LTCFs [26]. In a Canadian surveillance study, rhinovirus caused 59 percent of respiratory outbreaks during a six-month period in 2009, and disease was sometimes severe [26].

Tuberculosis — Screening for latent tuberculosis (TB) infection (LTBI) among individuals in LTCFs has been a routine practice in the past; subsequently, enthusiasm for routine testing and treatment of LTBI has waned [27-30]. The goal of testing for LTBI is to identify individuals who are at increased risk for the development of TB and therefore would benefit from treatment of LTBI. Testing for LTBI is warranted to identify individuals who are at risk of new infection and to identify individuals at increased risk of reactivation due to associated conditions. The indications and approach for LTBI testing are discussed separately; no modifications to this approach are needed for patients in LTCFs. (See "Tuberculosis infection (latent tuberculosis) in adults: Approach to diagnosis (screening)".)

Studies published in the 1980s suggested a high rate of TB transmission, new infection, and TB disease among older adults in nursing homes. In one study, disease was observed among 5.9 percent of individuals with skin test conversion in the absence of isoniazid therapy [31]. In addition, cohort studies noted lower rates of disease among those who received isoniazid for treatment of LTBI [32,33]. Subsequent studies have not shown comparable rates of infection or disease among LTCF residents, and the benefits of isoniazid appear more modest (with perhaps greater harm) than initially suggested [34-41].

Urinary tract infection — Urinary tract infections (UTIs) are the most common source of bacteremia in individuals in LTCFs [42]. In addition, a UTI is the most frequent reason for administration of antibiotics in LTCFs, although UTIs are often overdiagnosed in such settings [43,44]. In many cases, UTIs are diagnosed for nonspecific symptoms such as mental status change [4]. Fevers are often attributed to UTIs as well [45].

Risk factors for UTI include urinary catheters, benign prostatic hypertrophy and prostatitis in men, atrophic vaginitis and estrogen deficiency in women, diabetes, neurogenic bladder, dementia, dehydration, and functional impairment [46-49]. In one report, the incident rate of UTI among LTCF residents was 9.1 per 100 resident-days (among residents with indwelling catheters) and 2.8 per 1000 resident-days (among residents without indwelling catheters) [50]. Nursing home residents with a chronic indwelling catheter are more likely to have multidrug-resistant organisms than residents without those devices [51].

Important steps for prevention of catheter-associated UTI include avoidance of unnecessary catheterization, use of sterile technique for catheter placement, and removal of the catheter as soon as possible. (See "Catheter-associated urinary tract infection in adults", section on 'Prevention'.)

There is no role for screening asymptomatic patients for bacteriuria, as no treatment is indicated in such patients. (See "Asymptomatic bacteriuria in adults".)

Diarrheal disease — Diarrheal illness may spread rapidly in LTCFs; forms of transmission include person to person between residents, contaminated food, and airborne transmission. Residents of LTCFs are estimated to have the highest incidence of diarrhea in the developed world [52]. In the United States, approximately 0.05 to 2.0 episodes of gastroenteritis per 1000 patient days occur among LTCF residents [53]. In Australia between 2002 and 2008, 52 percent of gastroenteritis outbreaks occurred in the nursing home settings; 6.4 percent of patients were hospitalized and 2.7 percent died [54]. Older adults are at increased risk of infection in the setting of decreased gastric acid production, and morbidity and mortality is associated with dehydration [55].

Common etiologies of diarrhea include Clostridioides difficile, norovirus, and salmonella.

●C. difficile − Diarrheal illness may be caused by viral or bacterial pathogens. C. difficile is the most common cause of health care-associated diarrhea in resource-rich countries; older adults are affected disproportionately [56]. Among nursing home residents treated with antibiotics in the United States, 8 to 33 percent acquire C. difficile infection (CDI), and 10 to 30 percent of LTCF residents are colonized [57]. The incidence has more than doubled in recent decades [58,59]. Disease severity has also increased especially in those over 60 years of age. Nearly half of health care-onset CDI now occurs in LTCFs [59]. Adequate cleaning of LTCF environments, including removal of spores, is particularly difficult. There is no role for treatment of C. difficile infection in the setting of asymptomatic carriage. Issues related to prevention of C. difficile infection, including environmental cleaning and hand hygiene, are discussed further separately. (See "Clostridioides difficile infection: Prevention and control".)

●Norovirus − Norovirus is highly contagious and can be transmitted person to person or via food and water. LTCFs are the most common setting for norovirus outbreaks in the United States [60]. Nearly half of symptomatic patients shed virus for at least 21 days. Norovirus causes over 50 percent of acute gastroenteritis in LTCFs. During outbreaks, all-cause mortality in LTCFs increases.

●Other − Other causes of foodborne outbreaks include Salmonella, Staphylococcus, and E. coli O157:H7. In an Australian study of older adult residents of LTCFs between 2005 and 2009, the rates of Salmonella infection were higher, and the rates of toxigenic E. coli, Campylobacter, and Shigella lower, than in community residents [61]. Additional causes of diarrheal outbreaks in LTCFs include Shigella, Yersinia, Giardia, and Cryptosporidium. (See "Causes of acute infectious diarrhea and other foodborne illnesses in resource-abundant settings".)

Skin and soft tissue infection — Important skin and soft tissue infections in LTCFs include fungal infections (eg, tinea and candidiasis), viral infections (eg, shingles), infestations (eg, scabies), and infection related to pressure ulcers [62,63].

Scabies — Scabies outbreaks in LTCFs are common [64]. Scabies infection is associated with itch and rash; in some cases, the index case has crusted scabies, which is characterized by scaly lesions with an enormous mite load. The diagnosis should be confirmed by skin scrapings. Delayed diagnosis may occur in more than 10 percent of patients and is associated with chronic steroid use and long hospitalization [65]. (See "Scabies: Epidemiology, clinical features, and diagnosis", section on 'Crusted scabies'.)

Issues related to control of scabies transmission are discussed separately. (See "Scabies: Management", section on 'Contacts and environment'.)

Pressure ulcers — Pressure ulcers are common in LTCF residents. Most pressure ulcers do not reflect acute infection and do not warrant antibiotic therapy.

Prevention of complications associated with pressure ulcers requires use of support surfaces to minimize pressure, correct patient positioning, regular rotation, and attentive skin care. (See "Prevention of pressure-induced skin and soft tissue injury".)

Issues related to evaluation and management of pressure ulcers are discussed further separately. (See "Clinical staging and general management of pressure-induced skin and soft tissue injury".)

Pressure ulcers may be complicated by infection including osteomyelitis and/or bacteremia, especially in immobilized patients. Issues related to evaluation of infectious complications of pressure ulcers are discussed separately. (See "Infectious complications of pressure-induced skin and soft tissue injury".)

Tinea infection — Outbreaks of tinea infection can occur and may be perpetuated by contamination of washing areas, linens, or grooming equipment. Measures to control these infections should include prompt treatment of infected individuals, environmental cleaning, and surveillance. (See "Dermatophyte (tinea) infections".)

Conjunctivitis — Conjunctivitis may occur sporadically or in outbreaks and may be caused by bacterial (such as S. aureus) or viral (such as adenovirus) pathogens. The incidence in LTCF was 0.6 to 3.5 per 1000 patient-days in one report [66]. (See "Conjunctivitis".)

Group A streptococcal infection — Outbreaks of group A Streptococcus (GAS) infection in LTCFs have been described [67,68]. In one review including 1762 cases of invasive GAS infection, the incidence among LTCF residents (compared with community-based older adults) was 41 versus 7 cases per 100,000 population [67]. Patients in LTCFs were 1.5 times as likely to die from the infection as community-based patients (33 versus 21 percent). Outbreaks may occur over a long period of time, be challenging to identify, and can originate from an asymptomatic carrier [69].

Transmission is predominantly person to person, particularly via direct contact between residents.

Clinical syndromes due to GAS include cellulitis, toxic shock syndrome, pharyngitis, bronchitis, pneumonia, and bacteremia. These are discussed further separately. (See "Treatment and prevention of streptococcal pharyngitis in adults and children" and "Invasive group A streptococcal infection and toxic shock syndrome: Epidemiology, clinical manifestations, and diagnosis".)

Bloodborne and sexually transmitted pathogens — Transmission of HIV, hepatitis B, and hepatitis C in LTCFs can occur; both bloodborne and sexual transmission have been described [70]. Patients with severe mental illness in LTCFs may have a high incidence of hepatitis B and HIV infection. (See "Management of health care personnel exposed to HIV" and "Management of nonoccupational exposures to HIV and hepatitis B and C in adults" and "Prevention of hepatitis B virus and hepatitis C virus infection among health care providers".)

Issues related to safe injection practices are described separately. (See "Infection control in the outpatient setting", section on 'Safe injection practices'.)

ANTIMICROBIAL-RESISTANT ORGANISMS — Multidrug-resistant organisms (MDROs) are more common in LTCFs in the United States than in acute care setting [71-73]. Over 35 percent of United States nursing home residents are colonized with MDROs [72,74]. Many residents have extensive histories of health care exposure, indwelling devices, and the environment poses challenges to infection prevention [73,75,76]. Often, there is also considerable antibiotic overuse. Organisms may be transferred between acute and long-term care facilities via LTCF residents, and transmission can occur via contact with colonized skin or fecal-oral transmission.

Methicillin-resistant S. aureus — Approximately 10 to 50 percent of LTCF residents in United States are colonized with methicillin-resistant S. aureus (MRSA); one study including 412 residents reported a MRSA prevalence rate of 58 percent [77]. Risk factors for MRSA colonization in LTCFs include antimicrobial use, dependence on health care personnel for assistance with activities of daily living, presence of decubitus ulcers, and renal insufficiency [78,79].

Issues related to prevention and control of MRSA are discussed further separately. (See "Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Prevention and control".)

Vancomycin-resistant Enterococcus — The colonization rate of vancomycin-resistant Enterococcus (VRE) in LTCFs is variable. One study including 100 residents of 20 different LTCFs admitted to an acute care hospital noted 45 percent of patients were colonized with VRE on admission [80]. Another study including 1215 LTCF residents noted a VRE carriage rate of 9.6 percent [81].

Issues related to prevention of VRE infection are discussed further separately. (See "Vancomycin-resistant enterococci: Epidemiology, prevention, and control".)

Pneumococcus — Pneumococcal vaccination has led to an overall reduction in the prevalence of invasive pneumococcal infections [82]. However, penicillin-resistant strains persist, and outbreaks within LTCFs have been reported [83]. LTCFs have also been associated with outbreaks of multidrug-resistant pneumococcus, including isolates resistant to ceftriaxone [84].

Drug-resistant gram-negative organisms — Residents of LTCFs are at increased risk for acquisition of multidrug-resistant gram-negative bacteria (defined as resistance to three or more different antimicrobial classes), which are associated with prior antibiotic use [6,85-88]. LTCFs may serve as reservoirs for these organisms; in some facilities, colonization rates with these strains are comparable with or higher than colonization rates in acute care hospitals [87-93]. Colonization with a variety of resistant gram-negative bacteria have been reported, including fluoroquinolone-resistant E. coli, extended-spectrum beta-lactamase E. coli, multidrug-resistant Acinetobacter baumannii, and carbapenem-resistant Enterobacteriaceae. Ventilator use, fecal incontinence, and urinary catheterization were associated with increased risk.

The use of bundled intervention for prevention of infection due to drug-resistant gram-negative organisms is discussed separately. (See "Principles of infection control in long-term care facilities", section on 'Bundled interventions'.)

SUMMARY AND RECOMMENDATIONS

●Overview − Common causes of infection in long-term care facilities (LTCFs) include respiratory infection, diarrheal disease, urinary tract infection, and skin and soft tissue infections. (See 'Types of infections' above.)

●Influenza − Seasonal outbreaks of influenza are common and affect residents as well as staff. (See 'Influenza' above.)

●Pneumonia − Risk factors for pneumonia include chronic pulmonary disease, heart failure, and aspiration. Pathogens include organisms associated with community-acquired pneumonia and hospital-acquired pneumonia. (See 'Pneumonia' above.)

●Urinary tract infection − The urinary tract is a common site of infection among LTCF residents and the most frequent source of bacteremia. Urinary tract infections (UTIs) in LTCFs are often associated with urethral catheterization. There is no role for screening asymptomatic patients for bacteriuria. (See 'Urinary tract infection' above.)

●Diarrheal infection − Diarrheal illness may be caused by viral or bacterial pathogens. Clostridioides difficile is the most common cause of health care-associated diarrhea in resource-rich countries. Norovirus is highly contagious and can be transmitted person to person or via food and water. Other causes of foodborne outbreaks include Salmonella, Staphylococcus, and Escherichia coli O157:H7. (See 'Diarrheal disease' above.)

●Antimicrobial-resistant organisms − Antimicrobial-resistant organisms are increasingly recognized in LTCFs. Organisms may be transferred between acute and long-term care facilities via LTCF residents, and transmission can occur via contact with colonized skin or fecal-oral transmission. (See 'Antimicrobial-resistant organisms' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Rhonda Stuart, MD, who contributed to an earlier version of this topic review.