- Email: [email protected]
Methicillin-Resistant Staphylococcus aureus Infection in the Obstetric Setting
BRIEF REPORTS Methicillin-Resistant Staphylococcus aureus Infection in the Obstetric Setting Jan M. Kriebs, CNM, MSN Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly prevalent pathogen, both in the community and in hospitalized patients. The virulence of MRSA, coupled with its resistance to many frequently prescribed antibiotics, requires increased vigilance in the assessment and diagnosis of skin and soft tissue infections. This article reviews the epidemiology of MRSA and focuses on treatment of MRSA when it is diagnosed during pregnancy. J Midwifery Womens Health 2008;53:247–250 © 2008 by the American College of Nurse-Midwives. keywords: MRSA, mastitis, obstetrics, Staphylococcus aureus
INTRODUCTION Methicillin-resistant Staphylococcus aureus (MRSA) infections are an increasingly common complication in heath care. About 30% of the US population is colonized with S aureus, and approximately 1% of the population is colonized with MRSA.1 The most common carrier site is the nares. Intact skin can also be colonized with MRSA, as can the vagina. This report provides a brief overview of this infectious agent, its presentation in pregnancy, and treatment options. BACKGROUND Historically, most cases of MRSA have been found in hospitals among individuals with compromised immune systems or those who have recently undergone invasive procedures. More recently, MRSA has also been a problem in community settings among healthy persons who have not been recently hospitalized. Healthcareassociated MRSA (HA-MRSA) is primarily a cause of respiratory infections, wound infections, urinary tract infections, and blood stream infections. Communityassociated MRSA (CA-MRSA) is an increasingly common cause of soft tissue infections. Healthcare-Associated MRSA HA-MRSA infections accounted for about 64% of all S aureus isolates in intensive care hospital settings in 2003.2 HA-MRSA is primarily transmitted to individuals from patients with HA-MRSA infection. Health care workers and environments in which items like stetho-
Address correspondence to Jan M. Kriebs, CNM, MSN, FACNM, assistant professor, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland, 4th Floor, 405 W. Redwood, Baltimore, MD 21201. E-mail: [email protected]
Journal of Midwifery & Women’s Health • www.jmwh.org © 2008 by the American College of Nurse-Midwives Issued by Elsevier Inc.
scopes or blood pressure cuffs are used for several persons per day are other possible routes of transmission. The Association for Professionals in Infection Control and Epidemiology3 recently reported a carrier rate for MRSA of 46 per 1000 hospitalized patients, which is significantly higher than the rate found in previous reports. Health care-associated disease accounts for about 85% of invasive MRSA infection, including bacteremia, pneumonia, cellulitis, osteomyelitis, endocarditis, and septic shock. Those most at risk include the elderly, African Americans, and men; there is significant geographic variation in the incidence of disease. Twothirds of persons diagnosed with HA-MRSA infections will have identifiable risk factors for healthcare-associated disease, although the onset of their illness has occurred outside the hospital.4 Inadequate hand washing and failure to change gloves are ways in which staff can transmit MRSA between patients. Serial use of colonized medical equipment (such as a stethoscope) or inadequate cleaning of shared spaces (such as a triage bed) can also offer an opportunity for MRSA transmission. Colonization rates as high as 6% have been reported among staff at institutions where MRSA is a problem.5 Staff members with current sinus or respiratory infections or active dermatitis are at increased risk of transmitting MRSA if they have become colonized. However, the routine monitoring of health care workers and decolonization with mupirocin (Bactroban; GlaxoSmithKline, New York, NY) are not recommended, because the colonization is usually transient. If health care workers have skin lesions, they should be covered with a bioocclusive dressing during patient care. Community-Associated MRSA Unlike HA-MRSA, CA-MRSA is not associated with recent hospitalization and can spread within families or 247 1526-9523/08/$34.00 • doi:10.1016/j.jmwh.2008.02.001
Table 1. Diagnostic Criteria for CA-MRSA Versus HA-MRSA Diagnosis of MRSA was made in the outpatient setting or by a culture positive for MRSA less than 48 hours after admission to the hospital. No medical history of MRSA infection or colonization. No medical history in the past year of: Hospitalization Admission to a nursing home, skilled nursing facility, or hospice Dialysis Surgery No permanent indwelling catheters or medical devices that pass through the skin into the body. CA-MRSA ⫽ community-associated MRSA; HA-MRSA ⫽ healthcare-associated MRSA. Source: Centers for Disease Control and Prevention.6
communities by close contact. These strains may be susceptible to antimicrobials that are not effective against HA-MRSA strains. The criteria for distinguishing CAMRSA from HA-MRSA are listed in Table 1. CA-MRSA strains are most likely to present as newly arisen skin or soft tissue infections. Frequently, patients complain of “spider bites” that are actually MRSA lesions. When a patient presents with a new complaint of boils, folliculitis, furuncles (inflammatory nodules), carbuncles (subcutaneous abscesses draining through hair follicles), or other inflammatory skin lesions, CA-MRSA should be high on the differential diagnosis list. S aureus is the most common cause of these infections, and an increasing percentage of serious skin infections with S aureus are caused by MRSA. Necrotizing fasciitis, septicemia, pneumonia, and other more complex presentations are also possible complications.7 PREVENTION OF MRSA TRANSMISSION The ease of colonization means that good hand washing techniques, the use of gloves, gown, and mask as appropriate, and thorough cleaning of patient areas should be observed in the office setting (Table 2). There are no current recommendations for specific isolation procedures in the outpatient setting. The use of contact precautions (gown and gloves) in the presence of open lesions or contamination from a draining sore is essential. When medical equipment (e.g., stethoscope or blood pressure cuff) needs to be shared, it should be disinfected between patients when appropriate. Surfaces should be wiped down with disinfectant after a patient with a MRSA infection is in the room.8 Providing hand cleanser and offering masks for patients with respiratory symptoms might be reasonable precautions if there is a specific
Jan M. Kriebs, CNM, MSN, FACNM, is Director of the Midwifery Practice and assistant professor of Obstetrics, Gynecology and Reproductive Sciences at the University of Maryland Medical System, Baltimore, MD. She is the co-author of both Varney’s Midwifery and Primary Care for Midwives.
248
concern that a respiratory infection is secondary to MRSA. Patients presenting to the hospital with complaints suggesting skin infection should be given a private room whenever possible and placed on contact precautions until a diagnosis is made. Contact precautions include the use of gown and gloves when entering the room and the use of disposable medical equipment that can be left in the room whenever possible. Hand hygiene policies should be reinforced.5 Cultures of any open lesions should be sent to the laboratory, and the need for sensitivities if MRSA is present should be indicated on the laboratory request. Care should be taken to minimize the risk of cross-contamination of patient rooms or medical equipment. Patients may need to be grouped into specific units (cohorts) to limit cross-contamination.5 The risk of family members acquiring the infection should be stressed to the patient, and preventive hygiene measures should be reviewed. TREATMENT OF MRSA-RELATED DERMATOLOGIC LESIONS The recommended treatment for purulent skin infections is incision and drainage. Antibiotics are not always needed. However, if MRSA is suspected as a potential cause of the infection, either trimethoprim/sulfamethoxazole (TMP/SFX; Bactrim DS, AR Scientific, Inc, Philadelphia, PA) twice daily for 14 days or clindamycin 300 mg four times daily for 14 days should be used. The US Food and Drug Administration (FDA) has not approved TMP/SFX for use in the treatment of skin infections, but it can be considered a first-line agent. Some “clindamycin susceptible” strains have at least partial resistance to the medication. These will appear on culture as clindamycin sensitive but erythromycin resistant.7 Tetracyclines can be used to treat MRSA, although not during pregnancy or lactation. Other medications should only be
Table 2. Techniques to Reduce MRSA Transmission Wash hands carefully and thoroughly Wear gloves to examine or treat open lesions Use gown and mask when needed to avoid contamination of clothes or splash/droplet exposure Culture suspicious skin lesions Consider active surveillance of at-risk populations Educate women about: Frequent hand washing with warm soapy water or antibacterial cleaner Keeping open lesions covered with a bandage Disposal of soiled bandages or materials that have touched an infected wound in separate bags Warning signs of MRSA breast infections Educate families about: Risks of intrafamilial spread of skin infections Hand washing Not sharing personal items, such as razors, sports equipment, bed linens, and towels
Volume 53, No. 3, May/June 2008
used in consultation with a clinician experienced in the management of infectious diseases. MRSA IN PREGNANT WOMEN MRSA can colonize the vagina as well as other body surfaces. Chen et al.9 tested group B streptococcus (GBS) screening cultures for staphylococcus and found that 0.5% of the 2963 vaginal-rectal cultures were positive for MRSA. The risk factors associated with HA-MRSA were not found in CA-MRSA positive women.10 Laibl et al.11 reviewed the records of 57 patients diagnosed with MRSA during pregnancy between 2000 and 2004. The incidence rose during that time from 2 cases in 2000 to 23 in 2003, the last full year of the study. Almost all (96%) of the cases presented as skin or soft tissue infections; the rest were wound infections.11 Several studies have identified women with postpartum mastitis and skin infections caused by CA-MRSA.9,11,12 Neonatal cellulitis and pustulosis consistent with peripartum transmission have also been described.13 Some institutions have begun screening women for MRSA at the time of obstetric admission if they are from communities with a high incidence of MRSA colonization or if they have had any hospitalizations within the last 12 months. A swab for culture of the anterior nares is standard, because the nares are the most commonly colonized site. Vaginal or perineal cultures are not standard. In addition, women should be questioned about recent boils or skin lesions. When women colonized with MRSA are admitted, contact precautions are instituted and the nursery is notified. Appropriate precautions should be established for both the mother and baby based on institutional policy. Separation of mother and infant is not recommended. Andrews et al.14 recently reported results from a study of more than 5000 pregnant women; although as many as 3.5% of women in their study were MRSA positive at 35 to 36 weeks’ gestation, there were no reports of early-onset MRSA in infants. MRSA AND BREASTFEEDING COMPLICATIONS MRSA transmission to newborns in breast milk has been documented in both preterm and healthy term infants. Behari et al.15 presented a case report of preterm triplets in which MRSA sepsis in one infant and conjunctivitis is another was caused by breast milk that was infected with MRSA. Kawada et al.16 demonstrated MRSA transmission from colonized mothers without active infection to term breastfeeding infants. Increasing numbers of mastitis diagnoses are related to MRSA.17 Cracked nipples can harbor S aureus. Livingstone and Stringer18 reported the results of a small study of women who had S aureus colonization on cracked nipples, comparing oral antibiotics, topical antibiotics, and improved breastfeeding technique. Women receiving systemic antibiotics had fewer episodes of mastitis.18 Journal of Midwifery & Women’s Health • www.jmwh.org
All mothers should be counseled about hand washing and the warning signs of mastitis. Mothers who are colonized with MRSA should also be aware that MRSA can cause mastitis. They should be encouraged to follow careful hygiene procedures and advised to remind their care provider of their MRSA status if they experience any symptoms of nipple damage or infection. Reddy et al.17 found that among women with MRSA mastitis, effective treatment may be delayed for 5 or more days. Because the initial antibiotic for mastitis is frequently dicloxacillin or a cephalosporin and therapy is often begun empirically, the importance of early follow up to evaluate healing cannot be overstressed. Nipple and milk cultures can be obtained at that time. When MRSA is suspected, clindamycin is an appropriate initial therapy. Persistent mastitis should be treated as if the diagnosis could be MRSA until culture results can be obtained. Ruth Lawrence, MD, a well-known breastfeeding expert, provided her interpretation of safe breastfeeding guidelines when the mother is colonized with MRSA in Breastfeeding Outlook: “An infant who is term and otherwise well, and home should continue breastfeeding. If still hospitalized, term and healthy, mother and infant can be isolated together [and breastfeeding can continue]. If mother is sick [and] if baby is positive, then breastfeed, but treat both. The main reason not to breastfeed would be an infant in the neonatal intensive care unit and premature/sick when the milk might be the only contact between them.”19 CONCLUSION The emergence of antibiotic-resistant bacteria requires clinicians to be vigilant. Whether managing the risk of exposure in clinical settings, screening for signs of infection, choosing an appropriate antibiotic, or obtaining cultures for evaluation of skin and breast infections, increased awareness of the dangers associated with MRSA and similar diseases can lead to more effective prevention efforts. REFERENCES 1. Kuehnert MJ, Kruszon-Moran D, Hill HA, McQuillan G, McAllister SK, Fosheim G, et al. Prevalence of Staphylococcus aureus nasal colonization in the United States 2001–2002. J Infect Dis 2006;193:169 –71. 2. Klevens RM, Edwards JR, Tenover FC, McDonald LC, Horan T, Gaynes R. Changes in the epidemiology of methicillinresistant Staphylococcus aureus in intensive care units in United States hospitals, 1992–2003. Clin Infect Dis 2006;43:387– 8. 3. Association for Professionals in Infection Control and Epidemiology Website. National prevalence study of methicillin-resistant Staphylococcus aureus (MRSA) in U.S. healthcare facilities. Available from: www.apic.org/Content/NavigationMenu/
249
ResearchFoundation/NationalMRSAPrevalenceStudy/MRSA_ Study_Results.htm [Accessed July 5, 2007]. 4. Klevens RM, Morrison MA, Nadle J, Petit S, Gershman K, Ray S, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA 2007;298:1763–71.
11. Laibl V, Sheffield JS, Roberts S, McIntire DD, Trevino S, Wendel GD. Clinical presentation of community-acquired methicillin-resistant Staphylococcus aureus in pregnancy. Obstet Gynecol 2005;106:461–5.
5. Henderson DK. Managing methicillin-resistant staphylococci: A paradigm for preventing nosocomial transmission of resistant organisms. Am J Infect Control 2006;34:S46 –54.
12. Saiman L, O’Keefe M, Graham PL III, Wu F, Said-Salim B, Kreisworth B, et al. Hospital transmission of community-acquired methicillin-resistant Staphylococcus aureus among postpartum women. Clin Infect Dis 2003;37:1313–9.
6. Centers for Disease Control and Prevention Website. Community-associated methicillin-resistant Staphylococcus aureus information for clinicians. Available from: www.cdc.gov/ncidod/ dhqp/ar_mrsa_ca_clinicians.html# [Accessed December 5, 2007].
13. Bratu S, Eramo A, Kopec R, Coughlin E, Ghitan M, Yost R, et al. Community-associated methicillin-resistant Staphylococcus aureus in hospital nursery and maternity units. Emerg Infect Dis 2005;11:808 –13.
7. Gorwitz RJ, Jernigan DB, Powers JH, Jernigan JA, Participants in the CDC Convened Experts’ Meeting on Management of MRSA in the Community. Strategies for clinical management of MRSA in the community: Summary of an experts’ meeting convened by the Centers for Disease Control and Prevention. Available from: www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html [Accessed July 4, 2007].
14. Andrews WW, Schelonka R, Waites K, Stamm A, Cliver SP, Moser S. Genital tract methicillin-resistant Staphylococcus aureus. Obstet Gynecol 2008;111113– 8.
8. Siegel JD, Rhinehart E, Jackson M, Chiarello L, the Healthcare Infection Control Practices Advisory Committee. Management of multidrug-resistant organisms in healthcare settings. Available from: www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf [Accessed October 31, 2007]. 9. Chen KT, Huard RC, Della-Latta P, Saiman L. Prevalence of methicillin-sensitive and methicillin-resistant Staphylococcus aureus in pregnant women. Obstet Gynecol 2006;108:482–7. 10. Chen KT, Campbell H, Borrell LM, Huard RC, Saiman L, Della-Latta P. Predictors and outcomes for pregnant women with vaginal-rectal carriage of community-acquired methicillin resistant Staphylococcus aureus. Am J Perinatol 2007;24:235– 40.
250
15. Behari P, Englund J, Alcasid G, Garcia-Houchins S, Weber SG. Transmission of methicillin-resistant Staphylococcus aureus to preterm infants through breast milk. Infect Control Hosp Epidemiol 2004;25:778 – 80. 16. Kawada M, Okuzumi K, Hitomi S, Sugushita C. Transmission of Staphylococcus aureus between healthy, lactating mothers and their infants by breastfeeding. J Hum Lact 2003;19:411–7. 17. Reddy P, Qi C, Zembower T, Noskin GA, Bolon M. Postpartum mastitis and community-acquired methicillin-resistant Staphylococcus aureus. Emerg Infect Dis 2007;13:298 –301. 18. Livingstone V, Stringer LJ. The treatment of Staphylococcus aureus–infected sore nipples: A randomized comparative study. J Hum Lact 1999;15:241– 6. 19. Biancuzzo M. Ask the expert. Breastfeeding Outlook 2005;4:6.
Volume 53, No. 3, May/June 2008
INTRODUCTION Methicillin-resistant Staphylococcus aureus (MRSA) infections are an increasingly common complication in heath care. About 30% of the US population is colonized with S aureus, and approximately 1% of the population is colonized with MRSA.1 The most common carrier site is the nares. Intact skin can also be colonized with MRSA, as can the vagina. This report provides a brief overview of this infectious agent, its presentation in pregnancy, and treatment options. BACKGROUND Historically, most cases of MRSA have been found in hospitals among individuals with compromised immune systems or those who have recently undergone invasive procedures. More recently, MRSA has also been a problem in community settings among healthy persons who have not been recently hospitalized. Healthcareassociated MRSA (HA-MRSA) is primarily a cause of respiratory infections, wound infections, urinary tract infections, and blood stream infections. Communityassociated MRSA (CA-MRSA) is an increasingly common cause of soft tissue infections. Healthcare-Associated MRSA HA-MRSA infections accounted for about 64% of all S aureus isolates in intensive care hospital settings in 2003.2 HA-MRSA is primarily transmitted to individuals from patients with HA-MRSA infection. Health care workers and environments in which items like stetho-
Address correspondence to Jan M. Kriebs, CNM, MSN, FACNM, assistant professor, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland, 4th Floor, 405 W. Redwood, Baltimore, MD 21201. E-mail: [email protected]
Journal of Midwifery & Women’s Health • www.jmwh.org © 2008 by the American College of Nurse-Midwives Issued by Elsevier Inc.
scopes or blood pressure cuffs are used for several persons per day are other possible routes of transmission. The Association for Professionals in Infection Control and Epidemiology3 recently reported a carrier rate for MRSA of 46 per 1000 hospitalized patients, which is significantly higher than the rate found in previous reports. Health care-associated disease accounts for about 85% of invasive MRSA infection, including bacteremia, pneumonia, cellulitis, osteomyelitis, endocarditis, and septic shock. Those most at risk include the elderly, African Americans, and men; there is significant geographic variation in the incidence of disease. Twothirds of persons diagnosed with HA-MRSA infections will have identifiable risk factors for healthcare-associated disease, although the onset of their illness has occurred outside the hospital.4 Inadequate hand washing and failure to change gloves are ways in which staff can transmit MRSA between patients. Serial use of colonized medical equipment (such as a stethoscope) or inadequate cleaning of shared spaces (such as a triage bed) can also offer an opportunity for MRSA transmission. Colonization rates as high as 6% have been reported among staff at institutions where MRSA is a problem.5 Staff members with current sinus or respiratory infections or active dermatitis are at increased risk of transmitting MRSA if they have become colonized. However, the routine monitoring of health care workers and decolonization with mupirocin (Bactroban; GlaxoSmithKline, New York, NY) are not recommended, because the colonization is usually transient. If health care workers have skin lesions, they should be covered with a bioocclusive dressing during patient care. Community-Associated MRSA Unlike HA-MRSA, CA-MRSA is not associated with recent hospitalization and can spread within families or 247 1526-9523/08/$34.00 • doi:10.1016/j.jmwh.2008.02.001
Table 1. Diagnostic Criteria for CA-MRSA Versus HA-MRSA Diagnosis of MRSA was made in the outpatient setting or by a culture positive for MRSA less than 48 hours after admission to the hospital. No medical history of MRSA infection or colonization. No medical history in the past year of: Hospitalization Admission to a nursing home, skilled nursing facility, or hospice Dialysis Surgery No permanent indwelling catheters or medical devices that pass through the skin into the body. CA-MRSA ⫽ community-associated MRSA; HA-MRSA ⫽ healthcare-associated MRSA. Source: Centers for Disease Control and Prevention.6
communities by close contact. These strains may be susceptible to antimicrobials that are not effective against HA-MRSA strains. The criteria for distinguishing CAMRSA from HA-MRSA are listed in Table 1. CA-MRSA strains are most likely to present as newly arisen skin or soft tissue infections. Frequently, patients complain of “spider bites” that are actually MRSA lesions. When a patient presents with a new complaint of boils, folliculitis, furuncles (inflammatory nodules), carbuncles (subcutaneous abscesses draining through hair follicles), or other inflammatory skin lesions, CA-MRSA should be high on the differential diagnosis list. S aureus is the most common cause of these infections, and an increasing percentage of serious skin infections with S aureus are caused by MRSA. Necrotizing fasciitis, septicemia, pneumonia, and other more complex presentations are also possible complications.7 PREVENTION OF MRSA TRANSMISSION The ease of colonization means that good hand washing techniques, the use of gloves, gown, and mask as appropriate, and thorough cleaning of patient areas should be observed in the office setting (Table 2). There are no current recommendations for specific isolation procedures in the outpatient setting. The use of contact precautions (gown and gloves) in the presence of open lesions or contamination from a draining sore is essential. When medical equipment (e.g., stethoscope or blood pressure cuff) needs to be shared, it should be disinfected between patients when appropriate. Surfaces should be wiped down with disinfectant after a patient with a MRSA infection is in the room.8 Providing hand cleanser and offering masks for patients with respiratory symptoms might be reasonable precautions if there is a specific
Jan M. Kriebs, CNM, MSN, FACNM, is Director of the Midwifery Practice and assistant professor of Obstetrics, Gynecology and Reproductive Sciences at the University of Maryland Medical System, Baltimore, MD. She is the co-author of both Varney’s Midwifery and Primary Care for Midwives.
248
concern that a respiratory infection is secondary to MRSA. Patients presenting to the hospital with complaints suggesting skin infection should be given a private room whenever possible and placed on contact precautions until a diagnosis is made. Contact precautions include the use of gown and gloves when entering the room and the use of disposable medical equipment that can be left in the room whenever possible. Hand hygiene policies should be reinforced.5 Cultures of any open lesions should be sent to the laboratory, and the need for sensitivities if MRSA is present should be indicated on the laboratory request. Care should be taken to minimize the risk of cross-contamination of patient rooms or medical equipment. Patients may need to be grouped into specific units (cohorts) to limit cross-contamination.5 The risk of family members acquiring the infection should be stressed to the patient, and preventive hygiene measures should be reviewed. TREATMENT OF MRSA-RELATED DERMATOLOGIC LESIONS The recommended treatment for purulent skin infections is incision and drainage. Antibiotics are not always needed. However, if MRSA is suspected as a potential cause of the infection, either trimethoprim/sulfamethoxazole (TMP/SFX; Bactrim DS, AR Scientific, Inc, Philadelphia, PA) twice daily for 14 days or clindamycin 300 mg four times daily for 14 days should be used. The US Food and Drug Administration (FDA) has not approved TMP/SFX for use in the treatment of skin infections, but it can be considered a first-line agent. Some “clindamycin susceptible” strains have at least partial resistance to the medication. These will appear on culture as clindamycin sensitive but erythromycin resistant.7 Tetracyclines can be used to treat MRSA, although not during pregnancy or lactation. Other medications should only be
Table 2. Techniques to Reduce MRSA Transmission Wash hands carefully and thoroughly Wear gloves to examine or treat open lesions Use gown and mask when needed to avoid contamination of clothes or splash/droplet exposure Culture suspicious skin lesions Consider active surveillance of at-risk populations Educate women about: Frequent hand washing with warm soapy water or antibacterial cleaner Keeping open lesions covered with a bandage Disposal of soiled bandages or materials that have touched an infected wound in separate bags Warning signs of MRSA breast infections Educate families about: Risks of intrafamilial spread of skin infections Hand washing Not sharing personal items, such as razors, sports equipment, bed linens, and towels
Volume 53, No. 3, May/June 2008
used in consultation with a clinician experienced in the management of infectious diseases. MRSA IN PREGNANT WOMEN MRSA can colonize the vagina as well as other body surfaces. Chen et al.9 tested group B streptococcus (GBS) screening cultures for staphylococcus and found that 0.5% of the 2963 vaginal-rectal cultures were positive for MRSA. The risk factors associated with HA-MRSA were not found in CA-MRSA positive women.10 Laibl et al.11 reviewed the records of 57 patients diagnosed with MRSA during pregnancy between 2000 and 2004. The incidence rose during that time from 2 cases in 2000 to 23 in 2003, the last full year of the study. Almost all (96%) of the cases presented as skin or soft tissue infections; the rest were wound infections.11 Several studies have identified women with postpartum mastitis and skin infections caused by CA-MRSA.9,11,12 Neonatal cellulitis and pustulosis consistent with peripartum transmission have also been described.13 Some institutions have begun screening women for MRSA at the time of obstetric admission if they are from communities with a high incidence of MRSA colonization or if they have had any hospitalizations within the last 12 months. A swab for culture of the anterior nares is standard, because the nares are the most commonly colonized site. Vaginal or perineal cultures are not standard. In addition, women should be questioned about recent boils or skin lesions. When women colonized with MRSA are admitted, contact precautions are instituted and the nursery is notified. Appropriate precautions should be established for both the mother and baby based on institutional policy. Separation of mother and infant is not recommended. Andrews et al.14 recently reported results from a study of more than 5000 pregnant women; although as many as 3.5% of women in their study were MRSA positive at 35 to 36 weeks’ gestation, there were no reports of early-onset MRSA in infants. MRSA AND BREASTFEEDING COMPLICATIONS MRSA transmission to newborns in breast milk has been documented in both preterm and healthy term infants. Behari et al.15 presented a case report of preterm triplets in which MRSA sepsis in one infant and conjunctivitis is another was caused by breast milk that was infected with MRSA. Kawada et al.16 demonstrated MRSA transmission from colonized mothers without active infection to term breastfeeding infants. Increasing numbers of mastitis diagnoses are related to MRSA.17 Cracked nipples can harbor S aureus. Livingstone and Stringer18 reported the results of a small study of women who had S aureus colonization on cracked nipples, comparing oral antibiotics, topical antibiotics, and improved breastfeeding technique. Women receiving systemic antibiotics had fewer episodes of mastitis.18 Journal of Midwifery & Women’s Health • www.jmwh.org
All mothers should be counseled about hand washing and the warning signs of mastitis. Mothers who are colonized with MRSA should also be aware that MRSA can cause mastitis. They should be encouraged to follow careful hygiene procedures and advised to remind their care provider of their MRSA status if they experience any symptoms of nipple damage or infection. Reddy et al.17 found that among women with MRSA mastitis, effective treatment may be delayed for 5 or more days. Because the initial antibiotic for mastitis is frequently dicloxacillin or a cephalosporin and therapy is often begun empirically, the importance of early follow up to evaluate healing cannot be overstressed. Nipple and milk cultures can be obtained at that time. When MRSA is suspected, clindamycin is an appropriate initial therapy. Persistent mastitis should be treated as if the diagnosis could be MRSA until culture results can be obtained. Ruth Lawrence, MD, a well-known breastfeeding expert, provided her interpretation of safe breastfeeding guidelines when the mother is colonized with MRSA in Breastfeeding Outlook: “An infant who is term and otherwise well, and home should continue breastfeeding. If still hospitalized, term and healthy, mother and infant can be isolated together [and breastfeeding can continue]. If mother is sick [and] if baby is positive, then breastfeed, but treat both. The main reason not to breastfeed would be an infant in the neonatal intensive care unit and premature/sick when the milk might be the only contact between them.”19 CONCLUSION The emergence of antibiotic-resistant bacteria requires clinicians to be vigilant. Whether managing the risk of exposure in clinical settings, screening for signs of infection, choosing an appropriate antibiotic, or obtaining cultures for evaluation of skin and breast infections, increased awareness of the dangers associated with MRSA and similar diseases can lead to more effective prevention efforts. REFERENCES 1. Kuehnert MJ, Kruszon-Moran D, Hill HA, McQuillan G, McAllister SK, Fosheim G, et al. Prevalence of Staphylococcus aureus nasal colonization in the United States 2001–2002. J Infect Dis 2006;193:169 –71. 2. Klevens RM, Edwards JR, Tenover FC, McDonald LC, Horan T, Gaynes R. Changes in the epidemiology of methicillinresistant Staphylococcus aureus in intensive care units in United States hospitals, 1992–2003. Clin Infect Dis 2006;43:387– 8. 3. Association for Professionals in Infection Control and Epidemiology Website. National prevalence study of methicillin-resistant Staphylococcus aureus (MRSA) in U.S. healthcare facilities. Available from: www.apic.org/Content/NavigationMenu/
249
ResearchFoundation/NationalMRSAPrevalenceStudy/MRSA_ Study_Results.htm [Accessed July 5, 2007]. 4. Klevens RM, Morrison MA, Nadle J, Petit S, Gershman K, Ray S, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA 2007;298:1763–71.
11. Laibl V, Sheffield JS, Roberts S, McIntire DD, Trevino S, Wendel GD. Clinical presentation of community-acquired methicillin-resistant Staphylococcus aureus in pregnancy. Obstet Gynecol 2005;106:461–5.
5. Henderson DK. Managing methicillin-resistant staphylococci: A paradigm for preventing nosocomial transmission of resistant organisms. Am J Infect Control 2006;34:S46 –54.
12. Saiman L, O’Keefe M, Graham PL III, Wu F, Said-Salim B, Kreisworth B, et al. Hospital transmission of community-acquired methicillin-resistant Staphylococcus aureus among postpartum women. Clin Infect Dis 2003;37:1313–9.
6. Centers for Disease Control and Prevention Website. Community-associated methicillin-resistant Staphylococcus aureus information for clinicians. Available from: www.cdc.gov/ncidod/ dhqp/ar_mrsa_ca_clinicians.html# [Accessed December 5, 2007].
13. Bratu S, Eramo A, Kopec R, Coughlin E, Ghitan M, Yost R, et al. Community-associated methicillin-resistant Staphylococcus aureus in hospital nursery and maternity units. Emerg Infect Dis 2005;11:808 –13.
7. Gorwitz RJ, Jernigan DB, Powers JH, Jernigan JA, Participants in the CDC Convened Experts’ Meeting on Management of MRSA in the Community. Strategies for clinical management of MRSA in the community: Summary of an experts’ meeting convened by the Centers for Disease Control and Prevention. Available from: www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html [Accessed July 4, 2007].
14. Andrews WW, Schelonka R, Waites K, Stamm A, Cliver SP, Moser S. Genital tract methicillin-resistant Staphylococcus aureus. Obstet Gynecol 2008;111113– 8.
8. Siegel JD, Rhinehart E, Jackson M, Chiarello L, the Healthcare Infection Control Practices Advisory Committee. Management of multidrug-resistant organisms in healthcare settings. Available from: www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf [Accessed October 31, 2007]. 9. Chen KT, Huard RC, Della-Latta P, Saiman L. Prevalence of methicillin-sensitive and methicillin-resistant Staphylococcus aureus in pregnant women. Obstet Gynecol 2006;108:482–7. 10. Chen KT, Campbell H, Borrell LM, Huard RC, Saiman L, Della-Latta P. Predictors and outcomes for pregnant women with vaginal-rectal carriage of community-acquired methicillin resistant Staphylococcus aureus. Am J Perinatol 2007;24:235– 40.
250
15. Behari P, Englund J, Alcasid G, Garcia-Houchins S, Weber SG. Transmission of methicillin-resistant Staphylococcus aureus to preterm infants through breast milk. Infect Control Hosp Epidemiol 2004;25:778 – 80. 16. Kawada M, Okuzumi K, Hitomi S, Sugushita C. Transmission of Staphylococcus aureus between healthy, lactating mothers and their infants by breastfeeding. J Hum Lact 2003;19:411–7. 17. Reddy P, Qi C, Zembower T, Noskin GA, Bolon M. Postpartum mastitis and community-acquired methicillin-resistant Staphylococcus aureus. Emerg Infect Dis 2007;13:298 –301. 18. Livingstone V, Stringer LJ. The treatment of Staphylococcus aureus–infected sore nipples: A randomized comparative study. J Hum Lact 1999;15:241– 6. 19. Biancuzzo M. Ask the expert. Breastfeeding Outlook 2005;4:6.
Volume 53, No. 3, May/June 2008