Preharvest antibiotic use influences antibiotic resistance in Salmonella species from commercial poultry and swine farms in Lagos, Southwestern Nigeria

A large study in commercial poultry and pig farms in Nigeria (3,600 samples) found a relatively low prevalence of Salmonella (1.5%), but the isolates displayed widespread multidrug resistance and virulence factors. High resistance rates were observed for commonly used antibiotics such as erythromycin and tetracycline, supported by the presence of key resistance genes (e.g., tetA, sul1). Extensive antibiotic use for growth promotion and prophylaxis was common across farms, highlighting systemic drivers of resistance. Although correlations between antibiotic use and resistance were weak, the findings indicate that pre-harvest practices in food animal production contribute significantly to the emergence and spread of AMR, posing a potential public health risk and underscoring the need for stronger antimicrobial stewardship and One Health interventions.