Men Who Have Sex With Men: Sexual Behavior May Not Represent an Increased Risk for Methicillin-Resistant Staphylococcus aureus Colonization

Colonization by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging public health concern, particularly in groups traditionally considered at elevated risk, such as men who have sex with men (MSM). Despite this, the local epidemiology and behavioral determinants of CA-MRSA colonization in non-metropolitan regions remain insufficiently examined. This cross-sectional study assessed the prevalence of nasal colonization by CA-MRSA and methicillin-resistant coagulase-negative Staphylococci (MRCoNS) in a sample of 89 men (44 MSM and 45 heterosexual) from the central region of Rio Grande do Sul, Brazil. Nasal swabs were collected for microbiological culture, antimicrobial susceptibility testing, and molecular detection of the mecA and nuc genes through qPCR. Participants completed a self-administered questionnaire addressing sociodemographic information, sexual behaviors, and hygiene practices. Results showed a CA-MRSA prevalence of 20% among heterosexual men and 6.8% among MSM. Heterosexual orientation was identified as a significant risk factor (OR = 5.12; p =  0.021), whereas identifying as MSM appeared to be protective (OR = 0.20; p  = 0.021). Post-coital hygiene—specifically showering after sexual intercourse—was also found to be an independent protective factor (OR = 0.16; p  = 0.026). These findings challenge the conventional assumption that MSM universally constitute a high-risk group for CA-MRSA colonization. Instead, the higher prevalence detected among heterosexual men in this setting seems linked to individual hygiene behaviors, underscoring the relevance of universal preventive strategies emphasizing post-sex hygiene rather than approaches based solely on sexual orientation.