Molecular Characterization of Salmonella Enterica Serotype Typhimurium and Enteritidis Isolates from Food Samples in West Bank / Palestine

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Mahmoud Khreishi, Omayma
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An Najah National University
Salmonellae is one of the most frequently isolated foodborne pathogens. It is of major public health concern worldwide. Poultry meat and eggs represent an important source of Salmonellae organism for consumer health. The occurrence of virulence factors among Salmonellae Typhimurium (S. Typhimurium) appears to be lacking in Palestine. This study aimed to evaluate the occurrence of S. Typhimurium and S. Enteritidis using multiplex PCR (mPCR) among isolates collected from the local market, and to assess genetic relationships between strains of S. Typhimurium using virulence factors profiling and fingerprint profiling by RAPD-PCR and repetitive sequence PCR (REP-PCR) using ERIC-PCR and BOXAIR-PCR. The overall occurrence percentage of S. Typhimurium and S. Enteritidis was 54.9% and 0.0%, respectively. Only 13 out of 17 virulence genes were detected in these 28 isolates. The occurrence of the detected genes among these isolates was 100%, 50%, 46.4%, 39.3%, 35.7%, 35.7%, 32.1%, 25%, 25%, 17.6%, 14.3%, 14.3%, 3.6% for invA, sopB, prgH, sitC, pefA, tolC, cdtB, msgA, sifA, iroN, spiA, ipfC and pagC, respectively. The remaining virulence genes were absent in all of the isolates. Based on the combination of presence and absence of virulence genes, eight profiles were detected among these isolates, the most common genetic profile was V5 (each 32.1%). In the present study, on the basis of their genetic profile at cut-off point 96%, both ERIC and BOX primers allowed for discrimination into 4 and 6 clusters or clones of 16 S. Typhimurium isolates, respectively. Results of PCR typing methods showed that, strains S83 (chicken wings), S86 (chicken), and S87 (chicken) are clustered together using both ERIC-PCR and BOX-PCR typing methods and they had the same virulotype (V1) and strains S53 (chicken), S73 (chicken), S78 (beef burgher) and S80 (beef burgher) also clustered together by both typing methods and had the same virulotype (V8). The following conclusion with potential implication for the isolation and identification of Salmonellae from food sources were drawn; Contamination of food with Salmonellae especially with S. Typhimurium was high and indicated a bad microbiological quality of food. In addition, the data presented were considered the first attempt to identify a wide range of virulence genes of the S. Typhimurium isolates recovered from different food types in the Palestinian market. This emphasizes the need for rigorous public health and food safety methods to lower the human health hazard and risk associated with Salmonellae infection.