Genotypic characterization of Staphylococcus chromogenes and Staphylococcus simulans from Swedish cases of bovine subclinical mastitis

Staphylococcus chromogenes and simulans are commonly found in intramammary infections (IMI) associated with bovine subclinical mastitis, but little is known about genotypic variation relatedness within species. This includes knowledge genes encoding antimicrobial resistance (AMR) potential virulence factors (pVF). The aim of this study was therefore to investigate these aspects by whole-genome sequencing milk isolates from Swedish dairy cows mastitis an observational study. We also wanted if specific genotypes were persistent IMI the inflammatory response at udder quarter level. In total, 105 118 S. simulans, respectively, included. Isolates characterized using a 7-locus multilocus sequence typing (7-MLST), core genome analysis in-silico AMR pVF genes. Forty-seven types (ST) 7 clusters identified, most common ST ST-6 ST-109, both belonging cluster VII. A MLST scheme for not available, 3 5 subclusters described. Overall, substantial among herds Some several herds, indicating spread between herds. Moreover, within-herd same genotype observed Only few (blaZ, strpS194, vga(A)) detected limited number isolates, exception blaZ coding β-lactamase, which identified 22% ST-19, ST-102, ST-103 more carrying gene compared other STs. However, simulans. average total per isolate similar (n = 30) 33), some numbers presence or functional groups pVF, shown ST/clusters Differences potentially level subtypes subtypes. conclusion, results present generates new insight into epidemiology IMI, can have implications future prevention treatment related