Molecular and phylogenetic characterization of Staphylococcus aureus isolated from primary pyoderma in a goat from tropical India: an emerging zoonotic threat.

Staphylococcus aureus is a globally prevalent zoonotic pathogen frequently associated with pyoderma in humans; however, molecular data on primary staphylococcal pyoderma in Indian goats are meagre. This report presents the first molecular identification and phylogenetic analysis of S. aureus from a goat with primary pyoderma, along with clinical management. A four-month-old Malabari crossbred goat kid was presented to the Teaching Veterinary Clinical Complex, Mannuthy, with pustules and scab-like lesions on perianal and abdominal skin. Dermatological evaluation indicated primary pyoderma, and impression smears revealed Gram-positive cocci and neutrophils. The isolate was catalase positive and exhibited sensitivity to tetracycline, gentamicin, amoxicillin-sulbactam, ceftriaxone-tazobactam, and streptomycin, but showed resistance to multiple antibiotics. The isolate was identified as S. aureus by 16S rRNA gene sequencing. BLAST analysis revealed 99.48% sequence identity with S. aureus strains isolated from human cases of sepsis and pyoderma in Uzbekistan, India, and the USA, as well as with a complete genome sequence of a human blood isolate from Brazil. Phylogenetic analysis further demonstrated clustering with human isolates reported from multiple continents. A combination therapy of ceftriaxone-tazobactam and gentamicin for seven days based on culture and sensitivity test led to complete recovery. The genetic proximity to human pathogenic strains across diverse regions highlighted the broad host range of the bacterium. The findings of present study underscore the need for molecular surveillance, antimicrobial stewardship, and integrated One Health strategies to mitigate emerging zoonotic threats, particularly in regions with frequent human-livestock contact.