Molecular Identification of Salmonella in Poultry and Humans in Daloa, Côte d’Ivoire: PCR Detection and Confirmation by invA Gene Sequencing

Abstract

Background: Molecular documentation of Salmonella isolates from poultry and human sources in Daloa, Côte d’Ivoire, remains limited. This study examined selected isolates using culture-based methods, PCR and sequence analysis. Aims: To detect the invA gene in isolates of poultry and human origin and assess the similarity of amplified sequences to GenBank references. Study Design and Methods: A descriptive cross-sectional study was conducted from March to April 2026. Fifty poultry faecal samples were collected at Lobia Market, and three human clinical isolates were obtained from a hospital microbiology laboratory. Presumptive poultry isolates were selected following microbiological enrichment and culture on Hektoen agar. Selected bacterial cultures underwent invA-targeted PCR, Sanger sequencing and BLASTn comparison with reference sequences. Results: Of the 50 poultry samples, 37 showed bacterial growth on Hektoen agar, and 29 yielded presumptive Salmonella isolates. All 29 selected poultry isolates and three human isolates were PCR-positive (32/32; 100%). Thirty-two sequences were analysed; their lengths ranged from 181 to 223 bp, and nucleotide identities ranged from 95.68% to 99.52%. The 100% positivity refers only to the selected cultures and does not estimate infection prevalence in poultry or humans. Conclusion: Combined PCR and sequence comparisons supported molecular identification of the investigated isolates. Short invA fragments did not permit serovar identification or establish transmission between poultry and humans. The findings provide local evidence relevant to further One Health surveillance.