Survival of Salmonella spp. and Pathogenic Escherichia coli in Food Matrixes and Its Relevance in the Development of Proficiency Testing Samples

Monitoring of food products by government agencies for their compliance to regulatory limits is an essential step in controlling foodborne outbreaks. For monitoring purposes, an extensive setup of the surveillance system is used, which involves ISO 17025:2017 accredited laboratories for food testing. Participation in proficiency testing (PT) programs is a requirement of ISO 17025:2017, which ensures data accuracy and analyst competency. Participation in PT schemes is costly for laboratories in developing countries as most of the commercial suppliers are situated in the United States and Europe. The literature or data available on creation of microbiological proficiency testing is scanty as much of the data available with commercial suppliers are trade secrets, and there is only 0.06% of research articles available in the Scopus database on the topic. In this review article, an attempt is made to understand the factors impacting the survival of two important foodborne pathogens, i.e., Escherichia coli and Salmonella spp., by extracting information available from growth studies and root-cause analysis of various food safety incidents and recalls. Utilization of this information in the development of PT samples is discussed in this review article along with a focus on the availability of PT samples and associated ISO standards to formulate homogeneous and stable PT samples. This review article elaborates on the focus areas that can be considered by PT providers (PTP)-for example, initial inoculum level and preparation, strain type, microbial growth phase, the impact of different types of food matrixes including low-moisture food, antimicrobial components, pH, presence of competitor microbes, and environmental conditions involving storage temperature, time, and relative humidity. These focus areas can be used to successfully create PT samples by PTP in developing countries.