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Lactational mastitis

Lactational mastitis
Author:
J Michael Dixon, MD
Section Editors:
Anees B Chagpar, MD, MSc, MA, MPH, MBA, FACS, FRCS(C)
Daniel J Sexton, MD
Deputy Editors:
Elinor L Baron, MD, DTMH
Kristen Eckler, MD, FACOG
Literature review current through: Aug 2021. | This topic last updated: Jan 15, 2020.

INTRODUCTION — Lactational mastitis is a condition in which a woman's breast becomes painful, swollen, and red; it is most common in the first three months of breastfeeding. Initially, engorgement occurs because of poor milk drainage, probably related to nipple trauma with resultant swelling and compression of one or more milk ducts. If symptoms persist beyond 12 to 24 hours, the condition of infective lactational mastitis develops (since breast milk contains bacteria); this is characterized by pain, redness, fever, and malaise [1].

Issues related to lactational mastitis will be reviewed here. Issues related to other breast infections are discussed separately. (See "Nonlactational mastitis in adults" and "Primary breast abscess" and "Breast cellulitis and other skin disorders of the breast".)

EPIDEMIOLOGY — Lactational mastitis has been estimated to occur in 2 to 10 percent of breastfeeding women [2]. The incidence of mastitis requiring hospitalization is low; in one cohort including 136,459 new mothers, 127 women were hospitalized for mastitis, an incidence of 9 per 10,000 deliveries [3].

The risk of recurrence of mastitis in women with prior history of lactational mastitis is higher than in women with no prior history.

ETIOLOGY — Lactational mastitis often occurs in the setting of the following breastfeeding problems, which typically result in prolonged engorgement or poor drainage [4]:

Partial blockage of milk duct; reduced drainage results in stagnant milk distal to the obstruction

Oversupply of milk

Infrequent feedings

Nipple excoriation or cracking

Rapid weaning

Illness in mother or baby

Maternal stress or excessive fatigue

Maternal malnutrition

Organisms grow in the stagnant milk, resulting in infectious mastitis [1]. Infection can progress to local abscess formation if not treated promptly. Effective management and prevention of recurrence depends on resolution of the above factors.

Risk factors for lactational mastitis include prior history of mastitis, poor milk drainage, cracked nipples, use of cream on nipples (particularly antifungal cream), and using a breast pump [4,5].

The pathogenesis of lactational mastitis is complex and may include poorly understood interactions between the mammary-associated microbiota and host-specific genetic factors [6].

The risk of developing lactational mastitis can be reduced by frequent, complete emptying of the breast and by optimizing breastfeeding technique [7].

MICROBIOLOGY — Most episodes of lactational mastitis are caused by Staphylococcus aureus. Methicillin-resistant S. aureus (MRSA) has become an important pathogen in cases of lactational mastitis [2,8]; in one study including 127 women hospitalized for mastitis, MRSA was the most common pathogen isolated from women with mastitis alone (24 of 54 specimens) or mastitis and abscess (18 of 27 specimens).

Less frequent pathogens include Streptococcus pyogenes (group A or B), Escherichia coli, Bacteroides species, Corynebacterium species, and coagulase-negative staphylococci (eg, Staphylococcus lugdunensis).

In one study, milk was cultured from 192 women with mastitis and 466 breast milk donors (controls); two organisms, S. aureus and group B streptococci, were recovered significantly more frequently from women with mastitis than controls [1]. S. aureus has been widely reported as a causative organism in mastitis [9-11].

CLINICAL MANIFESTATIONS — Lactational mastitis is a condition in which a woman's breast becomes painful, swollen, and red (picture 1); it is most common in the first three months of breastfeeding. Initially, engorgement occurs because of poor milk drainage, probably related to nipple trauma with resultant swelling and compression of one or more milk ducts.

If symptoms persist beyond 12 to 24 hours, the condition of infective lactational mastitis develops (since breast milk contains bacteria) [1]. Infective lactational mastitis typically presents as a firm, red, painful, swollen area of one breast associated with fever >38.3ºC in a nursing mother; milk secretion may be diminished. Systemic complaints may include myalgia, chills, malaise, and flu-like symptoms.

In the early stages, the presentation can be subtle with few clinical signs; patients with advanced infection may present with a large area of breast swelling with overlying skin erythema. Reactive axillary lymphadenopathy may be associated with axillary pain and swelling.

DIAGNOSIS — The diagnosis of mastitis is based on clinical manifestations; laboratory tests are not needed.

Culture of the breast milk can be useful to guide selection of antibiotics; it is particularly important in the setting of infection that is severe, hospital acquired, or unresponsive to initial empiric antibiotics [7,12]. Blood cultures are warranted in the setting of severe infection (eg, hemodynamic instability, progressive erythema) but are otherwise not routinely necessary.

Imaging is useful if lactational mastitis does not respond within 48 to 72 hours to supportive care and antibiotics. Ultrasound is the most effective method of differentiating mastitis from breast abscess [13-17]. (See "Primary breast abscess".)

DIFFERENTIAL DIAGNOSIS

Severe engorgement – Engorgement occurs due to interstitial edema with onset of lactation or at other times with accumulation of excess milk. Mastitis may be distinguished from severe engorgement in that engorgement is bilateral, with generalized involvement [2]. Engorgement is not typically associated with systemic symptoms of fever and myalgia. (See "Common problems of breastfeeding and weaning", section on 'Engorgement'.)

Breast abscess – Mastitis can progress to local abscess formation if not treated promptly. A tender fluctuant area is suggestive of an abscess [18]. Ultrasonography is the most effective method of differentiating mastitis from a breast abscess and also facilitates guided drainage (image 1) [13-17]. (See "Primary breast abscess".)

Plugged duct A plugged duct is a localized area of milk stasis within the milk duct that causes distention of mammary tissue. Symptoms include a palpable lump with tenderness. A plugged duct may be distinguished from mastitis and breast abscess by the absence of systemic findings. (See "Common problems of breastfeeding and weaning", section on 'Plugged ducts'.)

Galactocele – A galactocele (also known as a milk retention cyst) is a cystic collection of fluid that is usually caused by an obstructed milk duct. Galactoceles present as soft cystic masses; they are not tender and are not associated with systemic manifestations. Ultrasonography may demonstrate a simple milk cyst or a complex mass. The diagnosis can be made on the basis of the clinical history and needle aspiration, which yields a milky substance. (See "Common problems of breastfeeding and weaning", section on 'Galactoceles'.)

Inflammatory breast cancer – Inflammatory breast cancer (IBC) should be considered if mastitis does not resolve with appropriate treatment. Erythema may improve to some degree with antibiotics in patients with IBC, but there are usually other manifestations of IBC present; IBC may be differentiated from mastitis by clinical manifestations of skin thickening due to edema, erythema, and peau d'orange appearance (picture 2 and picture 3 and picture 4). It is often associated with palpable axillary lymphadenopathy due to metastatic nodal involvement. The diagnosis is established via core biopsy. (See "Inflammatory breast cancer: Clinical features and treatment".)

The differential diagnosis of nonlactational mastitis is discussed separately. (See "Nonlactational mastitis in adults".)

TREATMENT

Clinical approach — Initial management of nonsevere lactational mastitis consists of symptomatic treatment to reduce pain and swelling (nonsteroidal inflammatory agents, cold compresses) and complete emptying of the breast (via ongoing breastfeeding, pumping, and/or hand expression); cessation of lactation is not required [7,10-12,14,18,19]. (See "Common problems of breastfeeding and weaning", section on 'Engorgement' and "Common problems of breastfeeding and weaning", section on 'Plugged ducts'.)

Management of infective lactational mastitis (lactational mastitis with persistent symptoms beyond 12 to 24 hours, with fever) consists of the above measures in addition to administration of antibiotic therapy with activity against S. aureus [9,10,12,13,19-28]. (See 'Antibiotic therapy' below.)

Data on treatment of lactational mastitis are limited. One observational study noted that emptying of the breast increased the rate of good outcome to 50 percent and significantly reduced the duration of symptoms; the addition of antibiotics to breast emptying increased the rate of good outcome to 96 percent [10].

If there is no clinical improvement within 48 to 72 hours, evaluation with ultrasound imaging to determine if there is an underlying abscess should be pursued. (See "Primary breast abscess".)

Antibiotic therapy — Culture of the breast milk can be useful to guide selection of antibiotics; it is particularly important in the setting of infection that is severe, hospital acquired, or unresponsive to appropriate antibiotics [7,12]. Blood cultures are warranted in the setting of severe infection (eg, hemodynamic instability, progressive erythema) but are otherwise not necessary.

Empiric therapy for lactational mastitis should include activity against S. aureus [10,19]:

In the setting of nonsevere infection in the absence of risk factors for methicillin-resistant S. aureus (MRSA) (table 1), outpatient therapy may be initiated with dicloxacillin (500 mg orally four times daily) or cephalexin (500 mg orally four times daily) [19]. In the setting of beta-lactam hypersensitivity, erythromycin 500 mg twice daily is preferred. Clindamycin 450 mg orally three times per day may also be used although caution is warranted because of the risk of Clostridioides difficile colitis.

In the setting of nonsevere infection with risk for MRSA (table 1), effective antibiotics include trimethoprim-sulfamethoxazole (TMP-SMX; 1 double-strength tablet orally twice daily) or clindamycin (450 mg orally three times daily).

TMP-SMX may be used in women who are breastfeeding healthy full-term infants who are at least one month old. TMP-SMX should be avoided in women who are breastfeeding newborn infants (<1 month old) or infants with glucose-6-phosphate dehydrogenase deficiency, and it should be used cautiously in women who are breastfeeding infants who are jaundiced, premature, or ill [29]. (See "Trimethoprim-sulfamethoxazole: An overview", section on 'Pregnancy and breastfeeding'.)

In the setting of severe infection (eg, hemodynamic instability, progressive erythema on antibiotics), empiric inpatient therapy with vancomycin (table 2) should be initiated; therapy should be tailored to culture and sensitivity results. Gram stain results demonstrating gram-negative rods should prompt empiric antibiotic therapy with a third-generation cephalosporin or a combination beta-lactam-beta-lactamase agent.

The optimal length of therapy is not certain; 10 to 14 days may reduce the risk of relapse, but shorter courses (5 to 7 days) can be used if the response to therapy is rapid and complete. In patients with severe mastitis or abscess, once there are signs of clinical improvement with no evidence of systemic toxicity, antibiotics may be transitioned from parenteral to oral therapy.

PREVENTION — For pregnant women with a history of lactational mastitis, administration of a Lactobacillus probiotic during late pregnancy may reduce the likelihood of lactational mastitis. In one randomized trial that included 108 pregnant women with history of infectious mastitis after previous pregnancies, women who received oral Lactobacillus salivarius PS2 had a lower incidence of mastitis than those who received placebo (25 versus 57 percent) [6].

It is unknown whether administration of probiotic therapy would be beneficial for pregnant women with no history of lactational mastitis.

RECURRENCE — Recurrent mastitis is uncommon but can result from inappropriate or incomplete antibiotic therapy and/or failure to correct problems with breastfeeding technique associated with incomplete milk drainage. Inflammatory breast carcinoma should be considered in the setting of mastitis that recurs repeatedly in the same location and/or does not respond to antibiotic therapy. (See 'Differential diagnosis' above.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Breastfeeding and infant nutrition".)

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: Common breastfeeding problems (The Basics)")

Beyond the Basics topic (see "Patient education: Common breastfeeding problems (Beyond the Basics)")

SUMMARY

Infective lactational mastitis is an infection of the breast associated with pain, redness, fever, myalgia, and malaise that occurs in the setting of breastfeeding. It is most common during the first six weeks postpartum. (See 'Introduction' above.)

Lactational mastitis often occurs in the setting of the breastfeeding problems that result in prolonged engorgement or poor drainage. (See 'Etiology' above.)

Lactational mastitis typically presents as a firm, red, tender, swollen area of one breast associated with fever >38.3ºC in a nursing mother. Systemic complaints may include myalgia, chills, malaise, and flu-like symptoms. (See 'Clinical manifestations' above.)

The diagnosis of infective mastitis is based on clinical manifestations. Culture of the breast milk can be useful to guide selection of antibiotics; it is particularly important in the setting of infection that is severe, hospital acquired, or unresponsive to initial antibiotics. Imaging is useful if lactational mastitis does not respond within 48 to 72 hours to supportive care and antibiotics. (See 'Diagnosis' above.)

The differential diagnosis of lactational mastitis includes severe engorgement, plugged duct, galactocele, breast abscess, and inflammatory breast cancer. (See 'Differential diagnosis' above.)

Most episodes of lactational mastitis are caused by Staphylococcus aureus. Methicillin-resistant S. aureus (MRSA) has become an important pathogen in cases of lactational mastitis. (See 'Microbiology' above.)

Initial management of nonsevere lactational mastitis consists of symptomatic treatment to reduce pain and swelling (nonsteroidal inflammatory agents, cold compresses) and complete emptying of the breast (via ongoing breastfeeding, pumping, and/or hand expression). Management of infective lactational mastitis (lactational mastitis with persistent symptoms beyond 12 to 24 hours, with fever) consists of the above measures in addition to administration of antibiotic therapy with activity against S. aureus. (See 'Treatment' above.)

REFERENCES

  1. Kvist LJ, Larsson BW, Hall-Lord ML, et al. The role of bacteria in lactational mastitis and some considerations of the use of antibiotic treatment. Int Breastfeed J 2008; 3:6.
  2. Committee on Health Care for Underserved Women, American College of Obstetricians and Gynecologists. ACOG Committee Opinion No. 361: Breastfeeding: maternal and infant aspects. Obstet Gynecol 2007; 109:479.
  3. Stafford I, Hernandez J, Laibl V, et al. Community-acquired methicillin-resistant Staphylococcus aureus among patients with puerperal mastitis requiring hospitalization. Obstet Gynecol 2008; 112:533.
  4. Foxman B, D'Arcy H, Gillespie B, et al. Lactation mastitis: occurrence and medical management among 946 breastfeeding women in the United States. Am J Epidemiol 2002; 155:103.
  5. Kinlay JR, O'Connell DL, Kinlay S. Risk factors for mastitis in breastfeeding women: results of a prospective cohort study. Aust N Z J Public Health 2001; 25:115.
  6. Fernández L, Cárdenas N, Arroyo R, et al. Prevention of Infectious Mastitis by Oral Administration of Lactobacillus salivarius PS2 During Late Pregnancy. Clin Infect Dis 2016; 62:568.
  7. Department of child and adolescent health and development. Mastitis: Causes and management. World Health Organization 2000. http://whqlibdoc.who.int/hq/2000/WHO_FCH_CAH_00.13.pdf (Accessed on August 17, 2009).
  8. Schoenfeld EM, McKay MP. Mastitis and methicillin-resistant Staphylococcus aureus (MRSA): the calm before the storm? J Emerg Med 2010; 38:e31.
  9. Dixon JM, Khan LR. Treatment of breast infection. BMJ 2011; 342:d396.
  10. Thomsen AC, Espersen T, Maigaard S. Course and treatment of milk stasis, noninfectious inflammation of the breast, and infectious mastitis in nursing women. Am J Obstet Gynecol 1984; 149:492.
  11. Amir LH. Breast pain in lactating women--mastitis or something else? Aust Fam Physician 2003; 32:141.
  12. Spencer JP. Management of mastitis in breastfeeding women. Am Fam Physician 2008; 78:727.
  13. Dixon JM. Breast abscess. Br J Hosp Med (Lond) 2007; 68:315.
  14. Prachniak GK. Common breastfeeding problems. Obstet Gynecol Clin North Am 2002; 29:77.
  15. Berens PD. Prenatal, intrapartum, and postpartum support of the lactating mother. Pediatr Clin North Am 2001; 48:365.
  16. Kvist LJ, Rydhstroem H. Factors related to breast abscess after delivery: a population-based study. BJOG 2005; 112:1070.
  17. Dener C, Inan A. Breast abscesses in lactating women. World J Surg 2003; 27:130.
  18. Academy of Breastfeeding Medicine Protocol Committee. ABM clinical protocol #4: mastitis. Revision, May 2008. Breastfeed Med 2008; 3:177.
  19. Jahanfar S, Ng CJ, Teng CL. Antibiotics for mastitis in breastfeeding women. Cochrane Database Syst Rev 2013; :CD005458.
  20. BMJ Best Practice. Mastitis and breast abscess: Management - Approach. http://bestpractice.bmj.com/best-practice/monograph/1084/treatment/step-by-step.html (Accessed on March 23, 2017).
  21. Jahanfar S, Ng CJ, Teng CL. Antibiotics for mastitis in breastfeeding women. Cochrane Database Syst Rev 2009; :CD005458.
  22. Dixon JM. Breast infection. In: ABC of Breast Diseases, Dixon JM (Ed), Blackwell Publishing, Oxford 2006. p.19.
  23. Dixon JM, Bundred NJ. Management of disorders of the ductal system and infections. In: Diseases of the Breast, Harris JR, Lippman ME, Morrow M, Osborne CK (Eds), Lippincott Williams & Wilkins, Philadelphia 2004. p.47.
  24. Hughes LE, Mansel RE, Webster DJT. Miscellaneous conditions. In: Benign Disorders and Diseases of the Breast: Current Concepts and Clinical Management, Hughes LE, Mansel RE, Webster DJT (Eds), Edward Arnold, London 2000. p.231.
  25. Arroyo R, Martín V, Maldonado A, et al. Treatment of infectious mastitis during lactation: antibiotics versus oral administration of Lactobacilli isolated from breast milk. Clin Infect Dis 2010; 50:1551.
  26. World Health Organization. Mastitis: Causes and management. WHO, Geneva 2000. http://www.who.int/maternal_child_adolescent/documents/fch_cah_00_13/en/ (Accessed on March 28, 2017).
  27. National Institute for Health and Care Excellence. Postnatal care up to 8 weeks after birth - Changes after publication. https://www.nice.org.uk/guidance/CG37/chapter/Changes-after-publication (Accessed on March 23, 2017).
  28. Amir LH, Academy of Breastfeeding Medicine Protocol Committee. ABM clinical protocol #4: Mastitis, revised March 2014. Breastfeed Med 2014; 9:239.
  29. Drugs and Lactation Database (LactMed) [Internet]. Trimethoprim-Sulfamethoxazole. https://www.ncbi.nlm.nih.gov/books/NBK501289/ (Accessed on January 17, 2020).
Topic 798 Version 32.0

References

1 : The role of bacteria in lactational mastitis and some considerations of the use of antibiotic treatment.

2 : ACOG Committee Opinion No. 361: Breastfeeding: maternal and infant aspects.

3 : Community-acquired methicillin-resistant Staphylococcus aureus among patients with puerperal mastitis requiring hospitalization.

4 : Lactation mastitis: occurrence and medical management among 946 breastfeeding women in the United States.

5 : Risk factors for mastitis in breastfeeding women: results of a prospective cohort study.

6 : Prevention of Infectious Mastitis by Oral Administration of Lactobacillus salivarius PS2 During Late Pregnancy.

7 : Prevention of Infectious Mastitis by Oral Administration of Lactobacillus salivarius PS2 During Late Pregnancy.

8 : Mastitis and methicillin-resistant Staphylococcus aureus (MRSA): the calm before the storm?

9 : Treatment of breast infection.

10 : Course and treatment of milk stasis, noninfectious inflammation of the breast, and infectious mastitis in nursing women.

11 : Breast pain in lactating women--mastitis or something else?

12 : Management of mastitis in breastfeeding women.

13 : Breast abscess.

14 : Common breastfeeding problems.

15 : Prenatal, intrapartum, and postpartum support of the lactating mother.

16 : Factors related to breast abscess after delivery: a population-based study.

17 : Breast abscesses in lactating women.

18 : ABM clinical protocol #4: mastitis. Revision, May 2008.

19 : Antibiotics for mastitis in breastfeeding women.

20 : Antibiotics for mastitis in breastfeeding women.

21 : Antibiotics for mastitis in breastfeeding women.

22 : Antibiotics for mastitis in breastfeeding women.

23 : Antibiotics for mastitis in breastfeeding women.

24 : Antibiotics for mastitis in breastfeeding women.

25 : Treatment of infectious mastitis during lactation: antibiotics versus oral administration of Lactobacilli isolated from breast milk.

26 : Treatment of infectious mastitis during lactation: antibiotics versus oral administration of Lactobacilli isolated from breast milk.

27 : Treatment of infectious mastitis during lactation: antibiotics versus oral administration of Lactobacilli isolated from breast milk.

28 : ABM clinical protocol #4: Mastitis, revised March 2014.