Surgical site infections: Causative pathogens and associated outcomes

Background: Surgical site infections (SSIs) are associated with substantial morbidity, mortality, and cost. Few studies have examined the causative pathogens, mortality, and economic burden among patients rehospitalized for SSIs. Methods: From 2003 to 2007, 8302 patients were readmitted to 97 US hospitals with a culture-confirmed SSI. We analyzed the causative pathogens and their associations with in-hospital mortality, length of stay (LOS), and cost. Results: The proportion of methicillin-resistant Staphylococcus aureus (MRSA) significantly increased among culture-positive SSI patients during the study period (16.1% to 20.6%, respectively, P<.0001). MRSA (compared with other) infections had higher raw mortality rates (1.4% vs 0.8%, respectively, P=.03), longer LOS (median, 6 vs 5 days, respectively, P<.0001), and higher hospital costs ($7036 vs $6134, respectively, P<.0001). The MRSA infection risk-adjusted attributable LOS increase was 0.93 days (95% confidence interval [CI]: 0.65-1.21; P<.0001), and cost increase was $1157 (95% CI: $641-$1644; P<.0001). Other significant independent risk factors increasing cost and LOS included illness severity, transfer from another health care facility, previous admission (<30 days), and other polymicrobial infections (P<.05). Conclusion: SSIs caused by MRSA increased significantly and were independently associated with economic burden. Admission illness severity, transfer from another health care setting, and recent hospitalization were associated with higher mortality, increased LOS, and cost.