394. Household Transmission of Community and Health-care associated Methicillin Resistant Staphylococcus Aureus Strains
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is distinct from healthcare-associated MRSA (HA-MRSA) in its epidemiology and microbiologic characteristics. This study describes MRSA transmission and body site colonization patterns within households (HH) of known colonized/infected individuals.

Methods: Index cases (IC) with MRSA colonization/infection were identified at participating institutions. Consenting HH with at least one HH contact (HC) were eligible. Questionnaires were completed and surveillance swabs were collected from nose, rectum, throat and skin sites. Cultures were performed using broth enrichment and both chromogenic agar and Colistin-nalidixic acid media. The first MRSA isolate from each IC/HC underwent pulse field gel electrophoresis (PFGE), SCCmec, Panton-Valentine leukocidin (PVL) and susceptibility testing. Strains carrying SCCmec IV/V and SCCmec II/III were considered CA-MRSA and HA-MRSA, respectively.

Results: 101 IC and 186 HC were enrolled. Overall, 90/186 (48%) of HC of IC became colonized at some point over the 3 months: 30% were detected at baseline visit, while 12%, 4%, and 2% were detected at first, second, and third follow-up visits, respectively. Of 169 MRSA typed, 88 (50%) were from IC [CA-MRSA (40; 45.4%), HA-MRSA (48; 54.5%)], 81 (46%) were from HC [CA-MRSA (45; 55.5%), HA-MRSA (36; 44.4%)] identified from 52 HH.Strain typing from all IC/HC strains was concordant within HH. Among colonized HC, the detection varied by body site: nasal 59%, forearm skin 45%, throat 40%, rectal 19%, axilla 10% and skin lesions 75%. Screening at multiple body sites improved detection of colonized HC: nasal + rectal + skin 83%, nasal + rectal + throat 78%, nasal + rectal 66%, nasal + rectal + axilla 67%. 11% (5/46) of pets in HH were colonized with MRSA.

Conclusion: MRSA transmission of both CA- and HA-MRSA strains among HC of MRSA-colonized IC is common and determination of transmission risk factors in HH settings is required.

Amna Faheem, MBBS, MPH1, Wil Ng, MHSc1, Allison Mcgeer, MD, MSc, FRCPC, FSHEA2,3, Andrew E. Simor, MD, FRCPC, FACP3,4, Antonella Gelosia, MLT2, Barbara Willey, ART2, Christine Watt, MSc, MLT4, David Richardson, MD5, Henry Wong, PhD4, Krystyna Ostrowska, MD6, Lee Vernich, MSc3, Lisa Louie, ART, MS4, Matthew Muller, MD, PhD, FRCPC3,7, Piraveina Gnanasuntharam, BSc2, Vanessa Porter, MLT2 and Kevin Katz, MD CM, MSc1,3, (1)Infection Prevention & Control, North York General Hospital, Toronto, ON, Canada, (2)Department of Microbiology, Mount Sinai Hospital, Toronto, ON, Canada, (3)University of Toronto, Toronto, ON, Canada, (4)Department of Microbiology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, (5)William Osler Health System, Brampton, ON, Canada, (6)Trillium Health Centre, Mississauga, ON, Canada, (7)St.Michael's Hospital, Toronto, ON, Canada


A. Faheem, None

W. Ng, None

A. Mcgeer, None

A. E. Simor, None

A. Gelosia, None

B. Willey, None

C. Watt, None

D. Richardson, None

H. Wong, None

K. Ostrowska, None

L. Vernich, None

L. Louie, None

M. Muller, None

P. Gnanasuntharam, None

V. Porter, None

K. Katz, None

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