Detection of Salmonella in Ready-to-Eat Food by Polymerase Chain Reaction and Culture Methods from Thammasat University (Rangsit Campus) Area Cafeterias

Abstract

Introduction: Salmonella is an important gut infectious agent in both humans and animals. It is one of the primary causes of gastrointestinal tract infections. The epidemic occurs in many countries around the world and is therefore a major public health concern.
Objective: To determine the prevalence of Salmonella from samples of ready-to-eat food by culture and PCR methods.
Methods: One hundred and twenty samples of ready-to-eat food were randomly selected at restaurants in Thammasat University. Xylose Lysine Deoxycholate (XLD) Agar, Salmonella - Shigella (SS) agar, and MacConkey’s agar were used as selective media by culture methods. PCR technique was used to detect the Salmonella enterotoxin (invA) gene of Salmonella.
Results: Samples from 7 cafeterias were analyzed. The culture method revealed Salmonella contamination in 64/120 (53.33%) of the samples of ready-to-eat food. The PCR method found contamination in 73/120 (60.83%) samples. The 64 samples found to be contaminated by the culture method were also identified by the PCR method, and the PCR method revealed contamination in an additional 9 samples which the culture method failed to identify.
Conclusions: In conclusion, the PCR-based method using invA gene-based primers could be an alternative approach for detection of Salmonella in food, the environment, and clinical samples.