Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia Arising From an Infected Episiotomy Site


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To the Editor:The article by Rotas et al1 describes a case of a postpartum woman with community-acquired methicillin-resistan Staphylococcus aureus (MRSA) sepsis resulting in necrotizing pneumonia and septic thrombophlebitis. The emerging problem of community-acquired MRSA, now seen in obstetrics, may be just the tip of the iceberg. Recently we admitted a similar case of a 22-year-old Ecuadorian woman with fever and pleuritic pain at day 8 postpartum. Her temperature was 40°C, and she exhibited decreased breath sounds at the right base and a separated episiotomy wound. Blood cultures grew MRSA resistant to penicillin and oxacillin. Chest computed tomography (CT) showed a right middle lobe wedge-shaped infiltrate, moderate right pleural effusion, and necrotizing infiltrates. Abdominal CT showed possible endometritis, a heterogeneous vaginal density, and a thrombus in the right-internal iliac vein. These two cases exhibit striking similarities: 1) community-acquired MRSA bacteremia with necrotizing pneumonia, and 2) septic pelvic thrombophlebitis following vaginal delivery.Community-acquired MRSA typically causes soft tissue infections; rarely does it cause bacteremia and pneumonia. Community-acquired MRSA usually belongs to one of two clonal groups (USA 300 or USA 400) and often possesses the virulent Panton-Valentine leukocidin gene. Community-acquired MRSA is more susceptible to antibiotics such as clindamycin, tetracycline, TMP-SMX, and vancomycin, distinguishing it from hospital-acquired MRSA.During 2002–2003, the Centers for Disease Control and Prevention (CDC) reported clusters of community-acquired MRSA infections that affected primarily athletes, prisoners, and homosexuals. Later, healthy children with toxic shock–like syndromes and healthy adults with necrotizing pneumonia were seen. The true prevalence of community-acquired MRSA is unknown, especially in the obstetric population.In 2005, surveillance cultures on hospital admissions revealed 7% or 53 of 726 patients who had nares that were culture-positive for MRSA, 33% or 16 of 53 who were positive for community-acquired MRSA, and an overall prevalence of 2.2%.2 Colonization may lead to infection, especially in the presence of compromised skin integrity or during surgery. Both cases likely resulted from infection at the episiotomy due to vaginal or rectal colonization by community-acquired MRSA.Community-acquired MRSA are displacing hospital-acquired MRSA in some hospitals, and the classic risk factors for MRSA infections, such as recent hospitalization, prior antibiotic use, immunosuppression, and invasive lines, are not found. These two cases suggest a possible role for preoperative screening for community-acquired MRSA in obstetric patients as is now routinely performed for group B streptococcus.

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