Virulence Profiles of Salmonella enterica Isolated from Three Food Matrices Collected from Retail Markets

Salmonella enterica is one of the most common foodborne pathogens associated with the consumption of contaminated porcine, dairy, and avian products. Nontyphoidal Salmonella is a major cause of bacterial diarrhea, responsible for ∼150 million cases and 60,000 deaths annually. The main goal of this study was to determine the prevalence of Salmonella spp. and to establish the virulence profile (VP) from genes (avrA, invE, ssaD, sseF, ssaQ, ttrC) and plasmid genes (pefA, spvB, spvC) in isolates obtained from cheese, chicken, and pork sold in food markets in Barrancabermeja, Colombia. A survey was conducted on 100 samples each matrix. The detection of Salmonella spp. followed the ISO 6579:2017 standards modified, and isolates were confirmed using the invA gene. In addition, single polymerase chain reaction assays were developed to detect the nine virulence genes. Salmonella spp. was found in 62%, 32%, and 14% of pork, chicken, and cheese samples, respectively. A total of 277 isolates were biochemically, serologically, and molecularly compatible with Salmonella spp. The most representative serogroups were C and B. Forty-seven combinations of virulence gene were detected; 53.5% of the pork isolates, 46.2% of the cheese isolates, and 39% of the chicken isolates were distributed among VP1, VP2, and VP3 suggesting a higher pathogenic potential. In addition, seven isolates harbored plasmid-encoded virulence genes (spvB and spvC), which are associated with increased invasiveness. The results revealed a higher prevalence of Salmonella spp. in pork and chicken compared with other studies conducted in Colombia. The serogroups identified include serovars that more frequently affect humans Salmonella Enteriditis, Salmonella Newport, and Salmonella Typhimurium. The isolations have the majority of the virulence genes studied. These findings highlight the need to improve control measures and educate food handlers to minimize the presence of Salmonella spp. and its potential transmission.