RESUMEN
Aim: Genomic analysis of a methicillin-resistant Staphylococcus aureus (MRSA) strain cultured from a non-migratory seabird at Fernando de Noronha Archipelago (Brazilian oceanic islands) was carried out to investigate the potential origin of MRSA genetic determinants in an ecological setting with minimal or absent antimicrobial selective pressure, and minimal interaction with humans and domestic animals. Results: The study determined mecA gene homology and the phylogenetic relatedness with mecA described in Staphylococcus sciuri, which was the major Staphylococcus spp. cultured from the birds. Our findings corroborate in silico assumptions that the mecA gene in MRSA strains clinically relevant for humans and animals originates from S. sciuri ancestors. Conclusion: Coagulase-negative staphylococci seem to be natural reservoirs of methicillin-resistant genes to S. aureus, even in environments with very low antimicrobial selection pressure.