Whole Genome Sequencing Analysis of Multi-Drug Resistant Staphylococcus aureus from Livestock and Food Handlers in Imo State

Methicillin-resistant Staphylococcus aureus associated with livestock represents a growing public health risk when transmitted to food handlers and consumers. This study performed whole genome sequencing analysis of multi-drug resistant Staphylococcus aureus isolates from livestock and food handlers in Imo State, South East Nigeria. Nasal swabs were collected from 100 food handlers working in meat markets and 200 livestock comprising cattle, pigs, and poultry across three local government areas. S. aureus was isolated by culture, confirmed by coagulase testing and PCR for nuc gene. Isolates were subjected to antimicrobial susceptibility testing, screened for mecA gene, and characterized by whole genome sequencing. Staphylococcus aureus was isolated from 29% of food handlers and 22.5% of livestock. Methicillin-resistant S. aureus was confirmed in 17.2% of food handler isolates and 12.4% of livestock isolates. Whole genome sequencing identified sequence type 8 and sequence type 88 as the predominant strains. Phylogenomic analysis demonstrated clustering of food handler and livestock isolates within shared lineages, suggesting direct interspecies transmission. Virulence genes encoding Panton-Valentine leukocidin were identified in 31.6% of sequenced isolates. The study concludes that methicillin-resistant S. aureus transmission occurs at the livestock-food handler interface in Imo State and that genome-based surveillance is feasible and informative in this setting. Keywords: Staphylococcus aureus, whole genome sequencing, antimicrobial resistance, food handlers, Imo State