Persistent Environmental Contamination with USA300 Methicillin-ResistantStaphylococcus aureusand Other Pathogenic Strain Types in Households withS. aureusSkin Infections

Abstract

Objective.To understand the genotypic spectrum of environmental contamination ofStaphylococcus aureusin households and its persistenceDesign.Prospective longitudinal cohort investigation.Setting.Index participants identified at 2 academic medical centers.Participants.Adults and children withS. aureusskin infections and their household contacts in Los Angeles and Chicago.Methods.Household fomites were surveyed for contamination at baseline and 3 months. All isolates underwent genetic typing.Results.We enrolled 346 households, 88% of which completed the 3-month follow-up visit.S. aureusenvironmental contamination was 49% at baseline and 51% at 3 months. Among households with a USA300 methicillin-resistantS. aureus(MRSA) body infection isolate, environmental contamination with an indistinguishable MRSA strain was 58% at baseline and 63% at 3 months. Baseline factors associated with environmental contamination by the index subject’s infection isolate were body colonization by any household member with the index subject’s infection isolate at baseline (odds ratio [OR], 10.93 [95% confidence interval (CI), 5.75–20.79]), higher housing density (OR, 1.47 [95% CI, 1.10–1.96]), and more frequent household fomite cleaning (OR, 1.62 [95% CI, 1.16–2.27]). Household environmental contamination with the index subject’s infection strain at 3 months was associated with USA300 MRSA and a synergistic interaction between baseline environmental contamination and body colonization by any household member with the index subject’s infection strain.Conclusions.We found that infectingS. aureusisolates frequently persisted environmentally in households 3 months after skin infection. Presence of pathogenicS. aureusstrain type in the environment in a household may represent a persistent reservoir that places household members at risk of future infection.Infect Control Hosp Epidemiol2014;35(11):1373–1382