Predictors and outcomes for pregnant women with vaginal-rectal carriage of community-associated methicillin-resistant Staphylococcus aureus

The purpose of this study was to determine the predictors and outcomes of pregnant women with vaginal-rectal carriage of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). We performed an unmatched 1:4 case-control study with two control groups (13 CA-MRSA cases, 52 methicillin-sensitive S. aureus (MSSA) controls, and 52 S. aureus-negative controls) via a retrospective medical record review. We found that CA-MRSA cases were 12.5 times significantly less likely to be colonized with group B streptococci (GBS) compared with MSSA controls in multi-variable analyses. When we compared MSSA patients with S. aureus-negative patients, we found that MSSA patients were 4.5 times significantly more likely to be colonized with GBS and 11 times significantly more likely to have a postpartum fever >= 100.4 degrees F in multivariable analyses. Traditional risk factors for hospital-associated MRSA do not appear to predict vaginal-rectal CA-MRSA carriage in pregnant women. Instead, CA-MRSA carriage is significantly associated with lack of GBS carriage. Additional microbiologic studies and epidemiologic studies are needed to clarify the relationship between S. aureus and GBS, given that these two colonizing organisms have the potential to become pathogens.