Mining and evaluating novel serovar-specific Salmonella C1 serogroup genes by polymerase chain reaction analysis

Abstract

Salmonella is a food-borne pathogen that causes worldwide infections in humans and animals. Over 2600 Salmonella serovars have been identified, and serogroup C1 (O:6, 7 epitopes) contains highly diverse serovars associated with high pathogenicity. Here, we aimed to develop a reliable polymerase chain reaction (PCR) method for detecting serovar-specific markers of Salmonella serogroup C1, with greater reliability and lower complexity than current methods. We identified three, two, four, and one novel genes unique to the Infantis, Rissen, Braenderup, and Virchow serovars. The PCR primers targeting these genes were specific for the target serovars. The detection limits of the PCR assays using 9 pairs of primers were 102–103 colony-forming units (CFUs)/mL and 104–105 CFU/g in pure bacterial cultures and artificially contaminated raw pork samples, respectively. No false-positive or false-negative results were obtained with 45 food samples, as determined by comparison with biochemical tests and traditional serotyping methods. The potential functions of all serovar-specific genes identified are unknown, except for one Rissen-specific gene that encodes a secreted protein. Our results imply that all 10 novel, specific genes can be considered as useful targets for detecting the Salmonella Infantis, Rissen, Braenderup, and Virchow serovars in food.