Multiplex PCR detection of antibiotic resistance and virulence genes in multidrug-resistant Staphylococcus aureus isolated from chickens, humans, rodents, and soil in Northern Tanzania

Staphylococcus aureus (S. aureus) is a zoonotic pathogen with public health and veterinary importance. We investigated the presence of antibiotic resistance genes (ARGs) and virulence genes (VGs) in 57 multidrug-resistant (MDR) S. aureus isolated from humans (n=17), chickens (n=14), rodents (n=13), and soil (n=13) using multiplex PCR. Overall, the distribution of ARGs revealed that the tetK was found in 18/57 (31.6%), mecA in 16/57 (28.1%), tetL in 5/57 (8.9%), and ermC in 1/57 (1.8%), while ermA and tetM were not detected. For VGs, the clfB was found in 6/57 (10.5 %), coa in 8/57 (14.0%), clfA in 3/57 (5.3%), hlg in 1/57 (1.8%), ebpS in 2/57 (3.5%), fnbB in 2/57 (3.5%), luk-PV in 6/57 (10.5%) and tst in 1/57 (1.8%). Resistance genes (tetK and mecA) and virulence determinants (clfB, coa, and luk-PV) were common in all sample sources, while tst, hlg, and fnbB were specific to human, chicken, and rodent isolates, respectively. Erythromycin phenotypic resistance results correlated with the presence of ermC (r=0.42), tetL (r=0.98), and mecA (r=0.51), while tetracycline resistance correlated with tetL (r=1.00) and mecA (r=0.57) genes and methicillin resistance correlated with mecA (r=0.55) and tetL (r=0.98) genes. Positive correlations were noted between ARG (ermC) and VGs; clfA (r=0.57), hlg (r=1.00), and clfB (r=0.43), and between tetK and clfB (r=0.39); tetK and coa (r=0.36) genes. Principal component analysis (PCA) shows that tetL, ermC, and mecA contributed to tetracycline, erythromycin, and methicillin resistance, respectively. The widespread presence of resistance and virulence genes, often in combination, among MDR S. aureus in isolates from humans, chicken, rodents, and soil samples require comprehensive One-Health interventions.