Effects of Plasmid Curing on Multi-Drug-Resistant Salmonella from Poultry Litter in Nasarawa Town, Nasarawa State, Nigeria

The emergence of antibiotic resistance in bacteria, often mediated by chromosomal or plasmid-borne genes, poses a significant public health concern. This study investigated the impact of plasmid curing on multidrug-resistant Salmonella isolates recovered from poultry litter samples in Nasarawa town, Nasarawa State, Nigeria. A total of 96 poultry litter samples were processed. Using standard microbiological protocols, Salmonella species were isolated, characterised, tested for antibiotic susceptibility, and subjected to plasmid curing. Twenty-three Salmonella isolates were screened against ten commonly used antibiotics using the agar disc diffusion technique. Resistance levels of 56.5%, 43.5%, 34.9%, 39.2%, and 22% were observed for Augmentin, Sparfloxacin, Gentamicin, Co-trimoxazole, and Streptomycin, respectively, indicating that they are multidrug-resistant Salmonella strains. Acridine orange was employed as the curing agent. Notably, all five strains initially resistant to streptomycin became susceptible post-curing. Similarly, all 13 strains resistant to augmentin and 4 out ofthe 9 that were resistant to co-trimoxazole lost resistance after plasmid curing. Additionally, 6 out of 10 sparfloxacin-resistant strains became susceptible post-treatment. These findings suggest that plasmid-mediated mechanisms contribute significantly to multidrug resistance in poultry-derived Salmonella. Further molecular studies are recommended to characterize resistance plasmids and inform policies on prudent antibiotic use in animal husbandry.