Low prevalence of methicillin-resistant Staphylococcus aureus among men who have sex with men attending an STI clinic in Amsterdam: a cross-sectional study

Objective: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is common among men who have sex with men (MSM) in the USA. It is unknown whether this is also the case in Amsterdam, the Netherlands. Design: Cross-sectional study. Setting: Sexually transmitted infection outpatient low-threshold clinic, Amsterdam, the Netherlands. Participants: Between October 2008 and April 2010, a total of 211 men were included, in two groups: (1) 74 MSM with clinical signs of a skin or soft tissue infection (symptomatic group) and (2) 137 MSM without clinical signs of such infections (asymptomatic group). Primary outcome measures: S aureus and MRSA infection and/or colonisation. Swabs were collected from the anterior nasal cavity, throat, perineum, penile glans and, if present, from infected skin lesions. Culture for S aureus was carried out on blood agar plates and for MRSA on selective chromagar plates after enrichment in broth. If MRSA was found, the spa-gene was sequenced. Secondary outcome measures: Associated demographic characteristics, medical history, risk factors for colonisation with S aureus and high-risk sexual behaviour were collected through a self-completed questionnaire. Results: The prevalence of S aureus colonisation in the nares was 37%, the pharynx 11%, the perianal region 12%, the glans penis 10% and in skin lesions 40%. In multivariable analysis adjusting for age, anogenital S aureus colonisation was significantly associated with the symptomatic group (p=0.01) and marginally with HIV (p=0.06). MRSA was diagnosed in two cases: prevalence 0.9% (95% CI 0.1% to 3.4%)). Neither had CA-MRSA strains. Conclusions: CA-MRSA among MSM in Amsterdam is rare. Genital colonisation of S aureus is not associated with high-risk sexual behaviour