PCR-based Salmonella Screening | Thermo Fisher Scientific

Reel Mahmoud, Global Market Development Manager – Food & Beverage and Salman Zeitouni, PhD., Global Product Manager – Molecular Solutions, Food & Beverage

Ensuring food safety and quality is pivotal in the food industry. Salmonella, a persistent foodborne pathogen, poses a continuous threat to public health and business reputation. Recent advances in Polymerase Chain Reaction (PCR) technology are revolutionizing detection and management of this hazard. In this entry of Food for Thought, we discuss why PCR-based Salmonella screening makes economic sense, especially in light of the latest USDA regulation updates.

The Critical Need for Managing Salmonella

Salmonella is a major cause of foodborne illness, causing over 1.35 million infections annually, 26,500 hospitalizations, and 420 deaths in the United States every year², leading to a total cost of around $4.1 billion each year³. Poultry products account for a substantial portion of these infections, with about 125,000 chicken-associated cases annually¹. This significant public health impact underscores the necessity for rapid, accurate detection methods.

Evolving regulatory landscape

In April 2024, the USDA's Food Safety and Inspection Service (FSIS) issued a proposed rule to reduce Salmonella contamination in poultry. This framework aimed to prevent raw poultry products contaminated with specific Salmonella serotypes from entering commerce. It sets thresholds for contamination levels and mandates comprehensive microbial monitoring programs to prevent pathogen contamination throughout the slaughter system.

More recently, in July 2024, the USDA further updated its framework, deep diving into the specifics of the proposed rule. The latest update requires that raw chicken carcasses, chicken parts, ground chicken, and ground turkey products containing Salmonella at or above 10 colony forming units (CFU) per gram/mL are considered adulterated. It also requires the elimination of any product containing identifiable levels of the serotypes of public health significance. For chicken carcasses, the serotypes of public health significance include Enteritidis, Typhimurium, and I 4,[5],12:I:- (a monophasic variant of Salmonella Typhimurium), while for comminuted turkey the significant serotypes are Hadar, Typhimurium, and Muenchen.

This update mandates that poultry establishments develop a microbial monitoring program incorporating statistical process control (SPC) monitoring methods. This requirement emphasizes the need for enhanced testing protocols to meet regulatory standards and prevent contamination. The need to both validate and quantify the identified serotypes poses both a challenge and an opportunity for poultry producers to upgrade their testing frameworks.

PCR Technology: Compliance with Speed and Accuracy

PCR testing transforms Salmonella screening by providing actionable results four to five days faster than traditional culture-based methods. This speed is crucial for maintaining production schedules and minimizing risks, particularly in the fast-moving, high-volume, low-margin poultry industry. Rapid, reliable results help mitigate prolonged shelf-life impacts and maintain business efficiency.

The technology offers several advantages over traditional culture media-based methods: not only does it provide faster results, but it also offers higher accuracy in quantification and identification of Salmonella serotypes significant to public health. The SureTect™ PCR System’s streamlined workflow is designed for ease of use and offers visibly simpler pathogen detection. Extensive validation studies demonstrate its accuracy and reliability, ensuring consistent performance across various pathogens and sample matrices.

Salmonella quantification and typing you can count on

The Thermo Scientific™ SureCount™ Salmonella species, Typhimurium and Enteritidis Multiplex PCR Kit offers a simple, all-in-one PCR solution designed to provide quantification and serotyping of the identified Salmonella species of public health concern in the latest USDA update. According to the AOAC-PTM validation study, the method is able to quantify 1 CFU per tested poultry rinses, raw meat and poultry samples (chicken carcass rinses and poultry parts, ground beef, ground pork and ground turkey). Hence this method can effectively replace laborious, time- and resource-hungry enumeration methods such as the most probable number (MPN) technique and help to drive productivity up, and costs down, without compromising on safety. This distinction makes it the only solution to enable validated simultaneous quantification and typing of Salmonella species, S. Typhimurium and S. Enteritidis in a single PCR test.

Automation: Preparing for Future Changes

The SureTect system is open and automatable, allowing laboratories to manage contamination effectively and scale operations as sample volumes increase. Automated processes such as cell lysis, and universal PCR preparation protocols, along with pre-dispensed reagents, significantly reduce hands-on time. The companion software, Thermo Scientific™ RapidFinder™ Analysis, simplifies workflow setup and result interpretation, as it automatically provides quantification results, thus increasing laboratory productivity and easing the pressure on operators.

The SureTect™ Advantage

The SureTect™ QuantStudio 5 Food Safety PCR System meets the dynamic needs of laboratories, supporting various tests including testing for other pathogens (Campylobacter, Listeria, ...etc), GMO and food species identification. Its open and flexible platform helps laboratories stay compliant with regulatory changes without needing new equipment. The RapidFinder™ Salmonella Multiplex Assay and SureCount™ Salmonella Multiplex Assay offer qualitative and quantitative results within 24 and 8 hours, respectively, ensuring compliance while maintaining operational efficiency.

Building a Culture of Food Safety

Effective Salmonella prevention starts with hygienic design and extends to comprehensive supply chain oversight. Enforcing cleaning protocols and maintaining sanitation at every stage are critical. Fostering a culture that prioritizes food safety reduces the risk of outbreaks and their associated impacts. This update in strategy to manage Salmonella will undoubtedly not be the last as the FSIS continues to monitor pathogens affecting the food supply chain; ensuring critical testing points throughout the manufacturing process are monitored rigorously puts poultry producers in an advantageous position to adapt to future requirements.

Conclusion

Chicken producers will need to consider overall lab efficiency when navigating updated regulations for Salmonella and avoiding the need for duplicate testing is crucial for maintaining time-to-result. As regulations become more stringent, adopting accurate, rapid technology is both a smart and necessary choice to safeguard public health and sustain food businesses. With evolving USDA policies, investing in robust food safety systems that enhance compliance and productivity is more critical than ever.

Thermo Scientific™ SureCount™ Salmonella species, Typhimurium and Enteritidis Multiplex PCR Kit workflow and RapidFinder™ Salmonella species, Typhimurium and Enteritidis Multiplex Flex Kit allow you to monitor and improve Salmonella control measures across the food production chain in a simple step.