Prevalence and antibiotic resistance profile of Salmonella spp. isolated from intestine of cattle sold in Abraka and environment

Abstract

Salmonella spp. remain a leading cause of foodborne illnesses globally, with cattle serving as key reservoirs for zoonotic transmission, particularly in low-resource settings like Nigeria where poor hygiene and antimicrobial misuse exacerbate risks. This study investigated the prevalence and antibiotic resistance profiles of Salmonella spp. isolated from the intestines of cattle sold in Abraka, Delta State, Nigeria. Using a cross-sectional design, intestinal samples were collected post-slaughter from five market sites with varying hygiene levels and processed via standard microbiological methods, including enrichment on MacConkey agar, and biochemical tests (e.g., citrate utilization, TSI. Results revealed a high prevalence of Salmonella spp. at 60% among the 10 samples collected (n=6 isolates), dominating over other microbes like Bacillus spp. and Acinetobacter (40%). Biochemical profiles confirmed classic Salmonella traits: Gram-negative, citrate-positive, and glucose-fermenting with gas production. Antimicrobial susceptibility testing via Kirby-Bauer disk diffusion (CLSI guidelines) against 10 antibiotics showed widespread multidrug resistance (MDR), with Multiple Antibiotic Resistance Index (MARI) values of 0.6–0.8. Isolates exhibited high resistance to streptomycin, augmentin, and cephalexin, with reduced inhibition zones visualized in assays, signaling threats to veterinary and human treatments. These findings show that informal markets are hotspots for MDR Salmonella dissemination, driven by unsatisfactory sanitation and over-the-counter antibiotic use. Urgent interventions, including biosecurity enhancements, stewardship programs, and surveillance programs, are recommended to mitigate zoonotic risks and safeguard public health in Nigeria's cattle industry.