Resistance profiles and antimicrobial resistance genes in Salmonella species isolated from live bird markets and processing environments in Plateau State, Nigeria

Salmonellosis, caused by Salmonella species, remains a major public health concern, particularly in developing countries such as Nigeria. Antimicrobial resistance (AMR) further complicates treatment and contributes to therapeutic failure worldwide. This study aimed to isolate Salmonella species from live bird markets and processing environments in Plateau State, Nigeria, and to determine their antimicrobial resistance profiles and associated resistance genes. A total of 78 presumptive Salmonella isolates were obtained from diverse samples, includinayochukwu Chibuike Ngng poultry droppings, soil, carcass processing water, slaughtering surfaces, and eviscerated organs. Antimicrobial susceptibility testing was conducted using eleven antibiotics. High resistance rates were observed for pefloxacin and trimethoprim-sulfamethoxazole (57.69% each), followed by tetracycline (41.03%) and ciprofloxacin (37.18%). Moderate resistance was recorded for chloramphenicol (32.05%), ampicillin (17.95%), and gentamicin (12.82%), while low resistance was observed for amoxicillin-clavulanate (2.56%) and cefotaxime (1.28%). All isolates were susceptible to ceftazidime and meropenem. Multidrug resistance (MDR) was detected in 53.33% of isolates, with Multiple Antibiotic Resistance Index (MARI) values ranging from 0.27 to 0.64. Molecular analysis of 31 isolates revealed the presence of resistance genes, with tetA and sul1 detected in 100% of both MDR and non-MDR isolates. The blaTEM and gyrA genes were present in all non-MDR isolates and in 85.71% and 76.19% of MDR isolates, respectively. The cat1 gene was not detected in any isolate. The high prevalence of antimicrobial-resistant Salmonella highlights a serious public health concern and underscores the need for improved antibiotic stewardship and surveillance to control the spread of multidrug-resistant strains in Nigeria.