Detection of AMR and identification of Salmonella enterica in indigenous, broiler and layers poultry in some major markets of Morogoro Municipal, Tanzania

Abstract

Background S almonella enterica is a major global cause of food-borne illness, with poultry products being a primary route of transmission to humans. The rise of antimicrobial-resistant strains in poultry significantly heightens public health risks, especially in low-and-middle income countries such as Tanzania. Methods A cross-sectional study was carried out from January to July 2025 in three live-bird markets in Morogoro Municipality, namely Bigwa, Mawenzi, and Kingalu. Cloacal swabs were collected from broiler, layer, and indigenous chickens. Samples were processed using selective enrichment, standard bacteriological culture, and biochemical tests, with confirmation by VITEK-MS (bioMérieux), and PCR targeting the invA gene. Antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method following Clinical and Laboratory Standards Institute 2025 guidelines. Results Salmonella enterica was detected in 1% (3/300) of the samples, all from broiler chickens in Bigwa market. VITEK-MS identified all isolates as Salmonella enterica with confidence scores of 99.9%. PCR confirmed the invA gene in all three isolates, producing a 796 bp amplicon. Antimicrobial susceptibility testing showed 100% resistance to tetracycline and trimethoprim–sulfamethoxazole, 66.7% resistance to ampicillin and azithromycin, and 33.3% resistance to ciprofloxacin, while all isolates remained susceptible to ceftriaxone. All isolates (3/3, 100%) exhibited multidrug resistance. Conclusion This study demonstrates the presence of multidrug-resistant Salmonella enterica in broiler chickens in Morogoro, Tanzania. Despite the limited number of isolates in this research, the detection of multidrug-resistant Salmonella enterica highlights a potential public health concern. Enhanced surveillance, responsible antimicrobial stewardship in poultry systems, and coordinated One Health interventions are recommended.