Molecular Epidemiology of Staphylococcus pseudintermedius in Post-Surgical Canine Infections Across Nigerian Teaching Hospitals: A Genomic Characterization Study

Staphylococcus pseudintermedius is an emerging zoonotic pathogen and a leading cause of canine post-surgical infections, with increasing reports of methicillin-resistant strains posing significant therapeutic challenges globally. This doctoral study performs the first comprehensive molecular epidemiological and whole-genome sequencing characterization of Staphylococcus pseudintermedius isolates from post-surgical canine wound infections across six Nigerian teaching hospitals representing all geopolitical zones, spanning 2020 to 2024. A total of 148 non-duplicate isolates were recovered from confirmed post-surgical wound infections. Whole-genome sequencing was performed using Illumina short-read sequencing platforms. Bioinformatic analyses characterized resistome profiles, virulome content, multilocus sequence typing, and phylogenetic relationships. Methicillin-resistant Staphylococcus pseudintermedius was confirmed in 22.3% of isolates via detection of the mecA gene. Novel sequence types not previously described in West African veterinary isolates were identified in 18% of analyzed genomes. Horizontal gene transfer of resistance determinants including tetracycline and aminoglycoside resistance genes was demonstrated between isolates from geographically separated institutions, suggesting inter-institutional pathogen dissemination. Biofilm formation genes were present in 91% of isolates, correlating with implant-associated infection severity. These original genomic findings provide a foundational contribution to the understanding of Staphylococcus pseudintermedius population structure in Nigerian veterinary surgical settings and establish a national genomic surveillance baseline with critical implications for One Health antimicrobial resistance management. Keywords: Staphylococcus pseudintermedius, whole-genome sequencing, post-surgical infection, methicillin resistance, molecular epidemiology.