First Isolation of Methicillin-Resistant Livestock-Associated Staphylococcus aureus CC398 and CC1 in Intensive Pig Production Farms in Argentina

Since the mid-2000s, livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) has been identified among pigs worldwide, CC398 being most relevant LA-MRSA clone. In present work, nasal swabs were taken from healthy of different age categories (25 to 154 days) 2019 2021 in four intensive farms located three provinces Argentina. The aim study was characterize first isolates that colonized fattening Argentina terms their resistance phenotype and genotype know circulating clones country. Antimicrobial susceptibility, presence mecA gene PCR screening evaluated all isolates. They resistant cefoxitin, penicillin, tetracycline, chloramphenicol ciprofloxacin but susceptible nitrofurantoin, rifampicin, vancomycin linezolid. Furthermore, 79% clindamycin lincomycin, 68% erythromycin, 58% gentamicin 37% trimethoprim/sulfamethoxazole. All multidrug resistant. clonal relation assessed by SmaI-PFGE (pulsed-field gel electrophoresis) a representative isolate each PFGE type whole genome sequenced Illumina. MLST (multilocus sequence typing), virulence genes SCCmec typing performed on differentiated types PFGE, they belonged sequence-type ST398 (58%) ST9, CC1 (42%) MLST. typeV several detected showed complete correlation with phenotypes. revealed colonizing belongs CC1, two MRSA lineages frequently associated other countries.