Occurrence and multidrug resistance of Salmonella spp. in food animals from selected districts of Bangladesh

Abstract Background Salmonella spp. are important zoonotic pathogens and a leading cause of foodborne illness worldwide, with antimicrobial-resistant (AMR) and multidrug-resistant (MDR) strains in livestock posing a growing public health concern. This study investigated the occurrence and AMR patterns of Salmonella spp. in cattle, goats, and chickens across selected districts of Bangladesh. A total of 180 fecal samples (60 each from cattle, goats, and chickens) were collected from four districts of the Dhaka division, Bangladesh, between July 2024 and June 2025, with one sample collected per farm to provide sampling across multiple farms. Salmonella spp. were isolated and identified using morphological and biochemical methods, followed by molecular confirmation using polymerase chain reaction targeted invA gene. AMR phenotypes and MDR patterns were determined using the disc diffusion method. Data were analyzed using descriptive statistics and Pearson’s chi-square test, with p < 0.05 considered statistically significant. Results Based on PCR detection of invA gene, 28 (15.56% (95% CI: 10.27–20.85%)) Salmonella spp. were isolated from the faeces of various food animals. The occurrence was numerically highest in in Gazipur (20.00%; 95% CI: 8.32–31.68%), followed by Narayanganj (15.56%; 95% CI: 4.98–26.14%), Dhaka (13.33%; 95% CI: 3.40–23.26%), and Munshiganj (13.33%; 95% CI: 3.40–23.26%), but the difference among districts was not statistically significant ( p = 0.836). Similarly, the occurrence was numerically higher in cattle (18.33%; 95% CI: 8.53–28.13%) than in chickens (16.67%; 95% CI: 7.24–26.10%) and goats (11.67%; 95% CI: 3.54–19.80%), with no statistically significant difference among animal species ( p = 0.629). All Salmonella isolates were 100% susceptible to meropenem, while 100% resistant to amoxicillin and erythromycin. Isolates from cattle and chickens also showed resistance to amoxicillin/clavulanic acid and tetracycline, while chicken isolates were additionally resistant to ciprofloxacin and chloramphenicol. Notably, all isolates were MDR, exhibiting resistance to at least four antimicrobial classes. Conclusions The detection of multidrug-resistant Salmonella spp. in food animals from the selected study areas indicates a potential public health concern and highlights the need for continued antimicrobial resistance surveillance. Further studies using larger and more representative samples are needed to better characterize the epidemiology and resistance determinants of Salmonella in food-animal production systems in Bangladesh.