Community-Associated Methicillin-Resistant Staphylococcus aureus Among Gay, Bisexual, and Other Men Who Have Sex with Men Living with HIV Who Engage in Chemsex in Barcelona, Spain: Epidemiological Patterns and Implications for Infection Control

Background: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are increasingly reported among gay, bisexual, and other men who have sex with men (GBMSM) engaging in chemsex, yet data remain limited. This ambispective cohort study conducted at Hospital Clínic of Barcelona (2018–2024) aimed to characterize CA-MRSA infections among GBMSM living with HIV. Methods: Epidemiological, behavioral, and clinical data were collected from medical records and standardized questionnaires. MRSA isolates from clinically indicated samples were identified by mass spectrometry and underwent antimicrobial susceptibility testing. Results: Among 446 participants, 62 (14%) were diagnosed with CA-MRSA, accounting for 109 infection episodes over a median follow-up of 3.21 years (IQR 1.39–5.05). All episodes involved skin and soft-tissue infections; 17% required hospitalization, 35% surgery, and 51% received non-active empirical antibiotics. Recurrent infections occurred in 32% of participants, and detectable HIV viral load was present in 28% of episodes. High levels of polydrug use were reported. Resistance to clindamycin (33%), cotrimoxazole (23%), and mupirocin (96%) was observed. Decolonization was attempted in 65% of participants. Conclusions: CA-MRSA infections were frequent, with substantial recurrence and antimicrobial resistance. These findings highlight challenges for infection control and antimicrobial stewardship and support further evaluation of preventive and decolonization strategies in this population.