Prevalence and Antibiotic Resistance Profile of Salmonella spp. Strains Isolated from the Vegetable Food Chain in Niamey, Niger

Abstract

Background: Salmonellosis is a bacterial infection in both humans and animals caused by various Salmonella isolates. The overall aim of this study was to determine the prevalence and antibiotic resistance profile of Salmonella isolates isolated from four (4) types of raw vegetables (carrot, lettuce, tomato and onion) in the urban community of Niamey. Methods: One hundred and twenty-four (124) samples of vegetables (carrot, lettuce, onion and tomato) were taken from three (3) market garden sites and five (5) markets in Niamey. Salmonella was tested via the ISO 6579:2017 4-step method: pre-enrichment, enrichment, isolation and biochemical identification, and the antibiotic resistance phenotype was determined via the standard Kirby–Bauer agar diffusion method. Results: Sampling sites that presented high Salmonella prevalence were notably site 1 (Gounti yena) (75.00%) and market 4 (Wadata) (40.00%). The overall level of Salmonella contamination in vegetables was 13.71%, including carrot (25.00%) and lettuce (15.38%) samples. The most common resistance phenotypes were ceftriazone (100%), amoxicillin + clavulanic acid (76.92%), ciprofloxacin (46.15%), aztreonam (33.33%) and imipenem (30.77%). The rate of multidrug resistance (MDR) was relatively high (73.33% [11/15]). Conclusion: The presence of multidrug-resistant Salmonella in this vegetables reflects the potential risk associated with their consumption. Research on the potential resistance and virulence genes of these isolates is important for better management of infectious diseases.