The environment as an unrecognized reservoir for community-associated methicillin resistant Staphylococcus aureus USA300: a case-control study.

<h4>Background</h4>Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are spreading, but the source of infections in non-epidemic settings remains poorly defined.<h4>Methods</h4>We carried out a community-based, case-control study investigat...

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Main Authors: Anne-Catrin Uhlemann, Justin Knox, Maureen Miller, Cory Hafer, Glenny Vasquez, Megan Ryan, Peter Vavagiakis, Qiuhu Shi, Franklin D Lowy
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2011-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0022407&type=printable
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Summary:<h4>Background</h4>Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are spreading, but the source of infections in non-epidemic settings remains poorly defined.<h4>Methods</h4>We carried out a community-based, case-control study investigating socio-demographic risk factors and infectious reservoirs associated with MRSA infections. Case patients presented with CA-MRSA infections to a New York hospital. Age-matched controls without infections were randomly selected from the hospital's Dental Clinic patient population. During a home visit, case and control subjects completed a questionnaire, nasal swabs were collected from index respondents and household members and standardized environmental surfaces were swabbed. Genotyping was performed on S. aureus isolates.<h4>Results</h4>We enrolled 95 case and 95 control subjects. Cases more frequently reported diabetes mellitus and a higher number of skin infections among household members. Among case households, 53 (56%) were environmentally contaminated with S. aureus, compared to 36 (38%) control households (p = .02). MRSA was detected on fomites in 30 (32%) case households and 5 (5%; p<.001) control households. More case patients, 20 (21%) were nasally colonized with MRSA than were control indexes, 2 (2%; p<.001). In a subgroup analysis, the clinical isolate (predominantly USA300), was more commonly detected on environmental surfaces in case households with recurrent MRSA infections (16/36, 44%) than those without (14/58, 24%, p = .04).<h4>Conclusions</h4>The higher frequency of environmental contamination of case households with S. aureus in general and MRSA in particular implicates this as a potential reservoir for recolonization and increased risk of infection. Environmental colonization may contribute to the community spread of epidemic strains such as USA300.
ISSN:1932-6203