Prevalence and risk factors associated with vancomycin-resistant Staphylococcus aureus precursor organism colonization among patients with chronic lower-extremity wounds in Southeastern Michigan

• Published in: Infection control and hospital epidemiology Vol. 34; no. 9; p. 954
• Main Authors: Tosh, Pritish K, Agolory, Simon, Strong, Bethany L, Verlee, Kerrie, Finks, Jennie, Hayakawa, Kayoko, Chopra, Teena, Kaye, Keith S, Gilpin, Nicholas, Carpenter, Christopher F, Haque, Nadia Z, Lamarato, Lois E, Zervos, Marcus J, Albrecht, Valerie S, McAllister, Sigrid K, Limbago, Brandi, Maccannell, Duncan R, McDougal, Linda K, Kallen, Alexander J, Guh, Alice Y
• Format: Journal Article
• Language: English
• Published: United States 01.09.2013
• Subjects: Adult; Aged; Aged, 80 and over; Female; Humans; Leg Injuries - complications; Leg Injuries - microbiology; Male; Michigan - epidemiology; Middle Aged; Prevalence; Risk Factors; Staphylococcal Infections - drug therapy; Staphylococcal Infections - epidemiology; Staphylococcal Infections - etiology; Staphylococcal Infections - microbiology; Vancomycin Resistance; Wound Infection - drug therapy; Wound Infection - epidemiology; Wound Infection - etiology; Wound Infection - microbiology; Michigan
• ISSN: 1559-6834
• DOI: 10.1086/671735

Of the 13 US vancomycin-resistant Staphylococcus aureus (VRSA) cases, 8 were identified in southeastern Michigan, primarily in patients with chronic lower-extremity wounds. VRSA infections develop when the vanA gene from vancomycin-resistant enterococcus (VRE) transfers to S. aureus. Inc18-like plasmids in VRE and pSK41-like plasmids in S. aureus appear to be important precursors to this transfer. Identify the prevalence of VRSA precursor organisms. Prospective cohort with embedded case-control study. Southeastern Michigan adults with chronic lower-extremity wounds. Adults presenting to 3 southeastern Michigan medical centers during the period February 15 through March 4, 2011, with chronic lower-extremity wounds had wound, nares, and perirectal swab specimens cultured for S. aureus and VRE, which were tested for pSK41-like and Inc18-like plasmids by polymerase chain reaction. We interviewed participants and reviewed clinical records. Risk factors for pSK41-positive S. aureus were assessed among all study participants (cohort analysis) and among only S. aureus-colonized participants (case-control analysis). Of 179 participants with wound cultures, 26% were colonized with methicillin-susceptible S. aureus, 27% were colonized with methicillin-resistant S. aureus, and 4% were colonized with VRE, although only 17% consented to perirectal culture. Six participants (3%) had pSK41-positive S. aureus, and none had Inc18-positive VRE. Having chronic wounds for over 2 years was associated with pSK41-positive S. aureus colonization in both analyses. Colonization with VRSA precursor organisms was rare. Having long-standing chronic wounds was a risk factor for pSK41-positive S. aureus colonization. Additional investigation into the prevalence of VRSA precursors among a larger cohort of patients is warranted.