1129. Novel Findings in the Epidemiology of Staphylococcus aureus in Patients Attending Inner City Sexually Transmitted Infections (STI) and Community Clinics in Calgary
Session: Poster Abstract Session: MRSA/VRE Epidemiology
Friday, October 9, 2015
Room: Poster Hall
Posters
  • Novel findings SAposter.pdf (1.9 MB)
  • Background: The predominant site of carriage of community acquired methicillin-resistant S. aureus (CA-MRSA) is not known.  We designed a prospective cohort study to measure the prevalence of carriage of SA, sites of colonization and risk factors associated with SA colonization in an inner city population in Calgary attending for STIs or general medical evaluation. 

    Methods: Following Ethics Board approval, written informed consent was obtained, a 50–item questionnaire was completed and swabs from nares, throat, axilla, groin, perineal-perianal, vaginal, upper back and interdigital web spaces (IDWS) were obtained. Following broth enrichment MSSA/MRSA were identified using standard laboratory procedures and confirmed by PCR assay (nuc, femA and mecA). Molecular characterization was done with pulsed-field electrophoresis (PGFE), SCCmec typing, spa and Multi Locus Sequence Typing (MLST). Risk factor data was collated and uni- and multivariate analyses were performed on STATA 9.2)

    Results: Of 285 participants included in the final analysis, the prevalence of colonization by SA for any site was 57.5%, (66.4% males / 33.5% females). MSSA carriage prevalence was 56.1% and 1.4% for MRSA (2/4 carried the USA300 strain). The most common site of MSSA colonization was the throat (41.4%) as a single or multiple site. The back and IDWS showed a colonization rate of 7.7 and 11.6% respectively. Univariate analysis of risk factors associated with SA colonization of any site were: use of illicit drugs with strangers (p=0.01), >6 heterosexual partners (p=0.002), oral sex (0.01), trimming pubic hair (p=0.007), any sports with mats (p=0.005). Only the first 2 variables remained significant on the multivariate analysis. We found 12 MSSA carriers with a strain closely related to USA300-MRSA by PFGE, MSLT and spa profile. 

    Conclusion: We found a very high prevalence of MSSA colonization in this population - 57.5% vs a usual prevalence of 22-32%. Two novel sites were identified for SA carriage: the upper back and the IDWS. The throat appears to be a significant reservoir of SA colonization in this population, which has implications for transmission. Strain relatedness between MSSA ST8 isolates and USA300-MRSA strain suggest a horizontal gain or loss of the SCCmec element.

    Alejandra Ugarte Torres, MD1, Ron Read, MD2, Angel Chu, MD3, Kunyan Zhang, MD, PhD4, Daniel Gregson, MD5,6, Thomas Louie, MD7,8, Judy Macdonald, MD9, Johanna Delongchamp, MSc10, Linda Ward, MLT11, Joann Mcclure, BSc10 and John Conly, MD12, (1)Medicine, University of Calgary, Alberta Health Services, Calgary, AB, Canada, (2)Medicine, University of Calgary and Alberta Health Services-Calgary STI Clinic, Calgary, AB, Canada, (3)Medicine, University of Calgary and Alberta Health Services-Calgary STI Clinic, Calgary, AB, Canada, (4)Pathology and Laboratory Medicine, Microbiology Immunology and Infectious Diseases, Medicine, University of Calgary and CLS, Alberta Health Services, Calgary, AB, Canada, (5)Pathology and Laboratory Medicine, Medicine, University of Calgary and CLS , Alberta Health Services, Calgary, AB, Canada, (6)Calgary Laboratory Services, Calgary, AB, Canada, (7)Foothills Medical Center, University of Calgary, Calgary, AB, Canada, (8)Medicine, Microbiology Immunology and Infectious Diseases, University of Calgary, Alberta Health Services, Calgary, AB, Canada, (9)Community Health Sciences, Alberta Health Services - Public Health, Calgary, AB, Canada, (10)Alberta Health Services, Calgary, AB, Canada, (11)Infection Prevention and Control, Alberta Health Services, Calgary, AB, Canada, (12)Medicine, Microbiology Immunology and Infectious Diseases , Pathology and Laboratory Medicine, University of Calgary, Alberta Health Services, Calgary, AB, Canada

    Disclosures:

    A. Ugarte Torres, None

    R. Read, None

    A. Chu, None

    K. Zhang, None

    D. Gregson, None

    T. Louie, None

    J. Macdonald, None

    J. Delongchamp, None

    L. Ward, None

    J. Mcclure, None

    J. Conly, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.