Multiplex PCR for Simultaneous Identification of 8 Common Salmonella Serovars

Introduction: Salmonella is a significant public health and food safety issue. This organism is the leading cause of foodborne illnesses by bacterial pathogens in the United States. Identifying this pathogen rapidly and accurately helps locate the source of contamination, implement corrective actions in a timely manner, and therefore ensure food safety for consumers and reduce economic loss for industry. PCR has been commonly used as a detection tool for Salmonella; however, in most cases, it should be combined with other techniques for further serotyping of isolated Salmonella.

Purpose: In this study, we developed a multiplex PCR assay to simultaneously identify eight different Salmonella enterica serovars, which have been most commonly associated with foodborne illnesses, including Enteritidis, Typhi, Javiania, Typhimurium, Newport, Gaminara, Michigan, and Agona.

Methods: Fifteen genetic loci were selected, and 17 primers were designed using Bioinformatics software and tested for multiplex PCR development. The final assay was run with 9 primers as two five-plex PCRs, and tested with various Salmonella serovars and common foodborne pathogens.

Results: The developed multiplex PCR could correctly identify the tested 8 serovars based on their unique amplification patterns. The results were reproducible and the developed assay did not show any cross-reactivity with other common foodborne pathogens or environmental bacteria. When the assay was tested with experimentally contaminated meat samples, the assay could identify the Salmonella serovars without any significant loss of sensitivity.

Significance: This study demonstrated the developed multiplex PCR assay could be a simple and rapid method for molecular subtyping of Salmonella enterica in food samples.