Retrospective study of tetracycline-resistant MRSA identified from January 2021 through August 2024 in two hospitals located in a swine-dense region of western France.
Clonal complex 398 (CC398) meticillin-resistant Staphylococcus aureus (MRSA) is classically associated with livestock, but its importance in human infections remains poorly documented in France. We conducted a retrospective study of tetracycline-resistant MRSA identified from January 2021 through August 2024 in two hospitals located in a swine-dense region of western France. Contemporaneous tetracycline-resistant porcine isolates were included to provide an animal comparison context. Among 616 human MRSA isolates, 66 were tetracycline resistant of which 21 were identified as CC398. Genomic analysis and epidemiologic data showed that most human isolates clustered within animal-origin clades closely related to porcine strains and were frequently associated with livestock exposure. A distinct human-adapted lineage (ST1232), characterized by Panton–Valentine leukocidin and immune evasion cluster genes, was identified exclusively in five community-acquired infections in patients without documented animal contact; two patients reported recent travel to Asia. Severe invasive infections were observed, mostly with animal-origin CC398 lineages. These findings highlight the genomic and clinical heterogeneity of CC398 MRSA and underscore the need for integrated One Health surveillance in livestock-dense regions.
Clonal complex 398 (CC398) meticillin-resistant Staphylococcus aureus (MRSA) is classically associated with livestock, but its importance in human infections remains poorly documented in France. We conducted a retrospective study of tetracycline-resistant MRSA identified from January 2021 through August 2024 in two hospitals located in a swine-dense region of western France. Contemporaneous tetracycline-resistant porcine isolates were included to provide an animal comparison context. Among 616 human MRSA isolates, 66 were tetracycline resistant of which 21 were identified as CC398. Genomic analysis and epidemiologic data showed that most human isolates clustered within animal-origin clades closely related to porcine strains and were frequently associated with livestock exposure. A distinct human-adapted lineage (ST1232), characterized by Panton–Valentine leukocidin and immune evasion cluster genes, was identified exclusively in five community-acquired infections in patients without documented animal contact; two patients reported recent travel to Asia. Severe invasive infections were observed, mostly with animal-origin CC398 lineages. These findings highlight the genomic and clinical heterogeneity of CC398 MRSA and underscore the need for integrated One Health surveillance in livestock-dense regions.