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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas.
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ABSTRACT |
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 ABSTRACT MATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Methods: This was a chart review of pregnant patients who were diagnosed with MRSA between January 1, 2000, and July 30, 2004. Data collected included demographic characteristics, clinical presentation, culture results, and pathogen susceptibilities. Patients’ pregnancy outcomes were compared with the general obstetric population during the study period.
Results: Fifty-seven charts were available for review. There were 2 cases in 2000, 4 in 2001, 11 in 2002, 23 in 2003, and 17 through July of 2004. Comorbid conditions included human immunodeficiency virus and acquired immunodeficiency syndrome (13%), asthma (11%), and diabetes (9%). Diagnostic culture was most commonly obtained in the second trimester (46%); however 18% of cases occurred in the postpartum period. Skin and soft tissue infections accounted for 96% of cases. The most common site for a lesion was the extremities (44%), followed by the buttocks (25%), and breast (mastitis) (23%). Fifty-eight percent of patients had recurrent episodes. Sixty-three percent of patients required inpatient treatment. All MRSA isolates were sensitive to trimethoprim-sulfamethoxazole, vancomycin, and rifampin. Other antibiotics to which the isolates were susceptible included gentamicin (98%) and levofloxacin (84%). In comparison with the general obstetric population, patients with MRSA were more likely to be multiparous and to have had a cesarean delivery.
Conclusion: Community-acquired MRSA is an emerging problem in our obstetric population. Most commonly, it presents as a skin or soft tissue infection that involves multiple sites. Recurrent skin abscesses during pregnancy should raise prompt investigation for MRSA.
Level of Evidence: II-3
Community-acquired MRSA is now recognized in many groups, including intravenous drug users, prisoners, children, and those who participate in contact sports. Colonization rates for children attending day care centers have been reported as high as 24%.3 In a state prison in Mississippi, 5.9% of female inmates were found to be colonized with MRSA.4 In February 2003, 5 cases of MRSA infection among members of a fencing club and their household contacts were reported in Colorado.5
Clinical community-acquired MRSA is most often characterized by soft tissue infections, particularly cellulitis and abscesses.6 Naimi et al7 reported that 75% of cases of community-acquired MRSA involved skin and soft tissue. In a study of children in southern New England in 2004, 83% of cases of community-acquired MRSA were diagnosed as soft tissue infections.8 Community-acquired MRSA is susceptible to a larger variety of non-ß lactam antibiotics than hospital-acquired MRSA and seems to have different genetic origins.8,9 Risk factors for community-acquired MRSA include poor hygiene, close living conditions, underlying dermatologic problems, and sharing of personal items.4
Despite the available information, the actual incidence of community-acquired MRSA is not known. It is thought to vary among different communities. It is likely that pregnant women are also susceptible to and have risk factors for community-acquired MRSA. Community-acquired MRSA has been reported as a cause of mastitis in postpartum women.10 Otherwise, little has been reported on this important group. The purpose of this study is to describe the presentation, management, and outcome of community-acquired MRSA in pregnancy and the postpartum period in our prenatal population. We also sought to analyze obstetric outcomes in women with community-acquired MRSA compared with our general obstetric population.
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MATERIALS AND METHODS |
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Medical records of pregnant patients with culture-proven MRSA were reviewed. Data collected were de-identified and included demographic characteristics, clinical presentation, culture results, pathogen susceptibilities, treatments, and obstetric outcomes. No patients were contacted for the purpose of data collection. Community-acquired MRSA was defined as S aureus resistant to erythromycin and ß lactam agents. Patients with chronic indwelling catheters or other medical devices were excluded, because they more likely represented hospital-acquired MRSA. Patients were not administered prophylactic antibiotics intrapartum solely because of their MRSA status. Newborns received only routine group B Streptococcus prophylaxis, as previously reported.11
Descriptive statistics were calculated on the cohort, and the patients’ pregnancy outcomes were compared with all other pregnant women who delivered at Parkland Memorial Hospital within the study period. Selected obstetric and neonatal outcomes were obtained from a previously described, continuously updated, obstetric computerized database.12 Statistical analyses included the 
2 for categorical data and the Student t test for continuous variables. P < .05 (2-tailed) was judged to be statistically significant. Data were analyzed by SAS 9.1 statistical software (SAS Institute, Cary, NC).
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RESULTS |
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The patients’ pregnancy outcomes are summarized in Table 2. Information was not available in 14 cases because the patients delivered elsewhere and were lost to follow-up. In the 43 patients in whom this information was available, 53% had a cesarean delivery. The cesarean delivery was a repeat in 66% of cases. Four cesarean deliveries were performed for nonreassuring fetal status. There were 2 cases of chorioamnionitis diagnosed in the cohort. There were no culture-proven cases of early onset neonatal sepsis. There were 2 cases of preterm, premature rupture of membranes, accounting for 2 of the 3 births before 34 weeks. These patients delivered at 32 and 33 weeks of gestation. One patient delivered spontaneously at 24 weeks. Two of the 3 neonates required mechanical ventilation.
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The obstetric outcomes of the MRSA patients were then compared with the general obstetric population (Table 3). During the study period, 57,314 women delivered at Parkland Hospital in the same labor and delivery units where the MRSA patients were admitted. The 2 groups were significantly different in terms of mode of delivery and history of a previous cesarean delivery (P < .001 and P < .001). The mean gestational age at delivery and the mean birth weight were not significantly different between the 2 groups. The general obstetric population contained a significantly higher percentage of nulliparous patients. Other indications for cesarean delivery and rates of chorioamnionitis were not significantly different between the 2 groups.
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The characteristics of the MRSA infections are listed in Table 4. Skin and soft tissue infections accounted for 96% of cases. The most common sites for infection were an extremity (44%), buttock (25%), breast (23%), vulva or groin (21%), and abdomen (21%). Soft tissue infections ranged in size from 1 cm to 10 cm. In 9 cases, patients presented complaining of a ‘'spider bite,’’ despite not having seen a spider in the home. Three patients were admitted for postoperative wound infections. All 3 were postpartum, and they were judged to have community-acquired MRSA based on antibiotic sensitivities. Two of the patients had undergone a cesarean delivery, and 1 presented with an infected postpartum tubal ligation incision. Two patients were found incidentally to have MRSA in their urine during routine prenatal screening. In 58% of patients, multiple sites of infection were reported. Among the patients with multiple sites of infection, 15% were infected with HIV, and 12% had diabetes. Among those patients with only a single site of infection, 9% were infected with HIV, and 4% had diabetes.
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Sixty-three percent of the patients required inpatient admission for treatment of infection. One patient required admission to the intensive care unit for septicemia. Cephalexin was the most common antibiotic given empirically before culture results. Only 7 patients initially received antibiotics to which MRSA was sensitive. The MRSA isolates were sensitive to rifampin, trimethoprim-sulfamethoxazole, and vancomycin in all cases (Table 4). In 98% of cases, the MRSA isolates were sensitive to gentamicin. The isolates were less often sensitive to levofloxacin and tetracycline, although the majority of cases were sensitive to these antibiotics as well. In cases where the pathogen was identified before discharge, intravenous antibiotics were changed to include vancomycin. Outpatient oral therapy was then guided by isolate sensitivities, with trimethoprim-sulfamethoxazole the most common agent prescribed.
With the exception of the patient admitted to the intensive care unit, all patients showed clinical improvement within 24 to 48 hours of the start of antibiotics regardless of what antibiotic was administered. Those patients with only a single site of infection never required more than 1 admission for treatment. In contrast, 21% of patients with multiple sites of infection required more than 1 admission. Patients requiring readmission for a soft tissue infection were treated with antibiotics to which the previous isolate was found to be sensitive.
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DISCUSSION |
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It is not unexpected that MRSA is found in our multiparous, pregnant women. They inherently possess risk factors associated with community-acquired MRSA. Carleton et al13 found that patients with community-acquired MRSA frequently had recent visits to an outpatient medical facility. Community-acquired MRSA has been increasingly found in child care centers and pediatric hospitals. The patients with community-acquired MRSA were significantly more likely to be multiparous compared with the general obstetric population. These women are frequently the primary child care provider for the family, placing them at risk for acquisition for community-acquired MRSA.
The data collected do not indicate that these women are at increased risk for chorioamnionitis or neonatal sepsis. However, they were significantly more likely to have had a cesarean delivery. This raises the question of whether community-acquired MRSA carriage actually originated in a prior pregnancy as a result of prophylactic antibiotic administration. It is our policy to give women undergoing a cesarean delivery 2 grams of cefazolin after cord clamping. It seems unlikely that it would be hospital-acquired, because sensitivity profiles would have been different.
The MRSA isolates were sensitive to several frequently used antibiotics. This is consistent with what has been previously reported.4,7,8 Importantly, there are therapeutic options available other than vancomycin. For example, the vast majority of isolates were sensitive to gentamicin and rifampin, 2 agents not currently used in the routine treatment of MRSA. For outpatient treatment, trimethoprim–sulfamethoxazole is available in an oral formulation. All isolates in this cohort were sensitive to it, and it has a favorable safety profile in pregnancy.14 Levaquin and tetracycline, because of potential fetal side effects, are not recommended for use in pregnancy.
Whether a patient should be admitted for intravenous antibiotics or allowed to remain outpatient on oral therapy should be decided by the clinician based on the site and severity of the infection. In cases where an abscess was present, our patients underwent incision and drainage with adjunctive antibiotic therapy. In some cases, the infection resolved with surgical management and empiric antibiotics to which the isolate was later found to be resistant. This supports a recent study from Young et al15 that reported that with adequate surgical drainage, skin and soft tissue infections severe enough to warrant hospitalization resolve regardless of whether the antimicrobial agent given to the patient had in vitro activity. Patients were not decolonized routinely, and it is not our practice to re-treat outpatients who have been found to have community-acquired MRSA that resolved. However, if there is a clinical recurrence, then the patient is empirically given antibiotics to which the prior isolate was sensitive.
There are several limitations to the current study. The study was a review of data collected from existing charts and data bases. It is possible that patients were treated for soft tissue infections without collecting a culture, thereby underestimating the true burden of disease. Patients were not contacted for information. Delivery data were only available in 43 of 57 cases, limiting our analysis of obstetric complications. The results are limited by the small population size, and this may explain the low rate of obstetric complications. Molecular typing, which could have possibly provided more information about the isolates, was not performed.
In conclusion, community-acquired MRSA is an important problem affecting pregnant women most often in the form of skin or soft tissue infections. Patients may report "spider bites" or multiple recurrences of soft tissue infections, and this should prompt further investigation for MRSA, including a culture with sensitivities. If MRSA is clinically suspected, inpatients can be treated with surgical drainage and intravenous vancomycin, and outpatients can be treated with trimethoprim–sulfamethoxazole.
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Footnotes |
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doi:10.1097/01.AOG.0000175142.79347.12
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REFERENCES |
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2. Enright MC. The evolution of a resistant pathogen–-the case of MRSA. Curr Opin Pharmacol 2003;3:474–9.[Medline]
3. Adcock PM, Pastor P, Medley F, Patterson JE, Murphy TV. Methicillin-resistant Staphylococcus aureus in two child care centers. J Infect Dis 1998;178:577–80.[Medline]
4. Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus aureus skin or soft tissue infections in a state prison, Mississippi, 2000. MMWR Morb Mortal Wkly Rep 2001;50:919-22.[Medline]
5. Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus aureus infections among competitive sports participants - Colorado, Indiana, Pennsylvania, and Los Angeles county, 2000-2003. MMWR Morb Mortal Wkly Rep 2003;52:793–5.[Medline]
6. Palavecino E. Community-acquired methicillin-resistant Staphylococcus aureus infections. Clin Lab Med 2004;24:403–18.[Medline]
7. Naimi TS, LeDell KH, Como-Sabetti K, Borchardt SM, Boxrud DJ, Etienne J, et al. Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection. JAMA 2003;290:2976–84.
8. Dietrich DW, Auld DB, Mermel LA. Community-acquired methicillin-resistant Staphylococcus aureus in southern New England children. Pediatrics 2004;113:e347–52.
9. Chambers HF. The changing epidemiology of Staphylococcus aureus? Emerg Infect Dis 2001;7:178–82.[Medline]
10. Saiman L, O’Keefe M, Graham PL 3rd, Wu F, Said-Salim B, Kreiswirth B, et al.. Hospital transmission of Community-acquired methicillin-resistant Staphylococcus aureus among postpartum women. Clin Infect Dis 2003;37:1313–9.[Medline]
11. Wendel GD Jr, Leveno KJ, Sanchez PJ, Jackson GL, McIntire DD, Siegel JD. Prevention of neonatal group B streptococcal disease: a combined intrapartum and neonatal protocol. Am J Obstet Gynecol 2002;186:618–26.[Medline]
12. McIntire DD, Bloom SL, Casey BM, Leveno KJ. Birthweight in relation to morbidity and mortality among newborn infants. N Engl J Med 1999;340:1234–8.
13. Carleton HA, Diep BA, Charlebois ED, Sensabaugh GF, Perdreau-Remington F. Community-adapted methicillin-resistant Staphylococcus aureus (MRSA): population dynamics of an expanding community reservoir of MRSA. J Infect Dis 2004;190:1730–8.[Medline]
14. Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation: a reference guide to fetal and neonatal risk, 5th ed. Baltimore (MD): Williams & Wilkins; 1998. p. 481–483, 1061-1063.
15. Young DM, Harris HW, Charlebois ED, Chambers H, Campbell A, Perdreau-Remington F, et al.. An epidemic of methicillin-resistant Staphylococcus aureus soft tissue infections among medically underserved patients. Arch Surg 2004;139:947–51.
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