S. aureus Infections in Chicago, 2006-2014: Increase in CA MSSA and Decrease in MRSA Incidence

Abstract

OBJECTIVETo examine trends in Staphylococcus aureus infections in adults and children at a single academic center in 2006–2014.DESIGNRetrospective cohort study.SETTINGInpatient, outpatient, and emergency department settings in a private, tertiary referral center.PATIENTSPatients with an infection culture that grew S. aureus in January 1, 2006, through March 31, 2014.METHODSThe first isolate per year for each patient was classified as community-associated (CA-), healthcare-associated (HA-), or HA-community–onset S. aureus. The incidence density of S. aureus, methicillin-susceptible S. aureus (MSSA), and methicillin-resistant S. aureus (MRSA) infections were calculated per quarter year.RESULTSOverall, 5,491 MRSA and 5,398 MSSA isolates were included. MRSA infections decreased by an average of 5.2% annually (P<.001). MRSA skin and soft-tissue infection (SSTI) incidence density decreased in adults (−3.5%; P<.001) and children (−2.9%; P=.004). MSSA infections at all anatomic sites increased by an average of 1.9% annually (P=.007) in adults and decreased 5.1% annually (P<.001) in children. MSSA SSTI incidence density increased in adults (+3.8%; P<.001) and children (+5.6%; P<.001). For MRSA and MSSA SSTI isolates, susceptibility to tetracycline and clindamycin decreased significantly.CONCLUSIONSIn 2006–2014, MRSA SSTI incidence decreased among children and adults. MSSA SSTI incidence density increased in children and adults, suggesting that current empiric SSTI treatment recommendations may not be optimal. Adults experienced an overall increase in MSSA infections, which may prompt consideration of the need for horizontal infection control practices to decrease MSSA infection risk.Infect Control Hosp Epidemiol 2017;38:1226–1234