Molecular Characterization of Salmonella Typhimurium and E. coli O157:H7 Isolated from Ready-to-eat Chicken Meat

Background: Virulence genes are important in the pathogenesis of bacteria and in the mechanism of bacterial pathogenicity.

Objective: The study aimed at molecular detection of virulence genes such as sdiA, fimH, InvA and fliC and determination of similarity and links among the isolates.

Method: A total of 67 isolates including 4 controls were tested by Polymerase Chain Reaction (PCR) with 4 primer pairs including invA, fliC, sdiA and fimH to avoid bias. Full sequences of the 16S-Sequencing gene of both strains were carried out with 29 Salmonella and 30 E. coli isolates that were positive for amplification at 1500bp.ward hierarchical clustering model and agglomeration procedure was used. Clustered grouping and relational affinity test were conducted and depicted by the dendrogram. Molecular identification and interpretation were done using BLASTn Protocol.

Result: None of the isolates were positive to the invA or fliC gene fragments. One isolate from each of Salmonella Typhimurium and E. coli O157:H7 was positive to sdiA and fimH respectively. Three E. coli isolates were positive with an amplification of 500bp which is specific for fimH genes. One of the isolates E459 showed amplification of fimH gene with multidrug resistance to 5 drugs namely Ceftazidime, Cefuroxime, Augmentin, Nitrofurantoin and Ampicillin. Four Salmonella isolates had an amplification of 274bp specific for sdiA gene. Two variants of E. coli O157:H7 (unit g1 and unit g2) were identified. A mutant strain Salmonella Typhimurium LTS (STMD1) causing human gastroenteritis was identified also, Salmonella Typhimurium DT104 isolated exhibited multiple resistant genes (ACSSuT, SGI1) against several antibiotics. These are of public health significance.

Conclusion: This study has indicated presence of sdiA and fimH genes in Salmonella typhimurium and E. coli 0157:H7 respectively isolated from ready-to-eat chicken meats from public eateries. It also indicated association of sdiA and fimH genes with multi-drugs resistance.