Antibiotic resistance and heavy metal tolerance of livestock-associated Methicillin-resistant Staphylococcus aureus (LA-MRSA) in selected livestock settings in Zaria, Nigeria

The inappropriate antibiotic use in animal husbandry raises concerns about possible reservoirs and transmission pathways of methicillin-resistant Staphylococcus aureus (MRSA) in livestock environments. This study assessed the antibiotic resistance and heavy metal tolerance of S. aureus isolated from livestock farm settings; abattoir and cattle ranch, and poultry farms in Zaria, Nigeria. This involved sample and data collection, heavy metal analysis, isolation of S. aureus, antibiogram, and heavy metal tolerance assay. Copper and Zinc concentrations varied in the water and animal wastes (cow dung and poultry litter) samples. Copper concentrations were higher in the cow dung (13.5-16.0 mg/L) compared to poultry litter (7.8-12.2mg/L). Zinc concentrations were higher in poultry litter (77.7-99.9 mg/L) compared to cow dung (44.1-66.4 mg/L). Out of a total of 76 S. aureus isolates, 65.8% (50/76) were MRSA with 77.8% (28/36) and 55% (22/40) from the abattoir and cattle ranch, and poultry farms respectively. S. aureus with MAR index ≥0.2 were greater for the abattoir and cattle ranch (75%) compared with those from the poultry farms (50%) with most isolates exhibiting beta-lactam resistance. MRSA distribution varied with sample type with most isolated from water samples. MRSA isolates from livestock handlers in the poultry farms (27.3%) were greater than those from the abattoir and cattle ranch (7.1%). S. aureus isolates exhibited varying Copper and Zinc tolerance limits irrespective of their source. Proper implementation of biosecurity measures, antimicrobial resistance (AMR) surveillance, and policies are required to decrease the transmission of MRSA and AMR dissemination in livestock settings.