Staphylococcus aureus colonization in children undergoing heart surgery.

Background: Staphylococcus aureus is an important cause of cardiac surgical site infection. Based on studies in adults, nasal screening to detect S aureuscolonization is used to guide decolonization and selection of prophylactic antibiotics. In our Children's Hospital, a sensitive polymerase chain reaction (PCR)-based assay is used to screen patients undergoing cardiac surgery for nasal colonization with methicillin-sensitive S aureus (MSSA) and methicillin-resistant S aureus (MRSA). Additionally for patients in diapers, cultures are used to detect MRSA colonization of the groin. The purpose of this study was to determine whether screening two anatomic locations results in a higher MRSA detection rate among children undergoing cardiac surgery.

Methods: A retrospective chart review determined whether the frequency of bacterial colonization with MRSA differed by anatomic site. Records for 322 pediatric cardiac surgery procedures performed between January 2009 and June 2011 were reviewed. Both a nasal PCR and a second anatomic site culture were performed before 102 procedures.

Results: The overall rate of colonization with MRSA and MSSA was 4.2% and 29.1%, respectively. Of the seven dually screened patients who tested positive for MRSA, two were identified solely via a groin test, four by nasal screening alone, and one by both the tests. Screening of only the nose would have failed to detect 28.6% of the MRSA cases.

Conclusion: Preoperative detection of MRSA colonization may be enhanced by screening both the nose and a second anatomic site. The clinical utility of the extranasal MRSA culture was limited due to the long assay turnaround time.