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Food Testing >> Resources >> Overview of Pathogen Testing White Paper

Overview of Pathogen Testing

Nothing destroys a brand faster than injuring or killing a customer. Companies that are responsible for foodborne outbreaks quickly lose consumer trust and risk going out of business or struggling for years to win back lost market share. With the Food Safety Modernization Act (FSMA), food safety managers and company officials can be held personally liable for criminal offenses related to the manufacture of harmful products. In addition to criminal liability, civil penalties can be substantial and can ruin both company and personal fortunes.

In some jurisdictions and industries, there are regulatory requirements that mandate pathogen testing. Such industries earned regulatory pressure due to a long history of failing to control pathogens in their products, resulting in significant morbidity and mortality among consumers. The bottom line is every manufacturer must deal with hazards associated with their products and processes. If pathogen risk is reasonably foreseeable, then pathogen testing is required to validate control processes and to verify that products are safe.

PATHOGEN TESTING TERMS YOU SHOULD KNOW

Indicator organism: Microbial indicators are a group, genus, species, strain, or metabolite whose presence or population size indicates the possible presence, population, or activity of another microbe or group of microbes.

Spoilage organism: If allowed to grow, microbes produce enzymes that can breakdown products to produce a large number of foul odors and offensive flavors and overall reduction in product quality. Microbial activity can also lead to color change, gas formation, slime formation, and texture loss.

PCR: Polymerase Chain Reaction (PCR) is a very common technique in pathogen testing. DNA is amplified through a series of heating and cooling, and the resulting fragments can be used to detect and identify a panel of pathogens.

Foodborne illness: Foodborne illnesses can occur at any stage of the food production and consumption process. Pathogen testing can prevent dangerous illness by making sure products are safe for consumers before purchase.

Food Safety Modernization Act (FSMA): This act was signed into law in 2011 and impacts all food products regulated by the FDA. In terms of pathogen testing, the FSMA focuses on preventing foodborne illness at all stages of production, and requires companies to test for pathogens that are known to be a risk.

WHAT KIND OF PATHOGENS COULD YOU BE AT RISK OF IN YOUR PRODUCTS OR RAW MATERIALS?

Salmonella

Salmonella is a bacterial genus that is a member of the Enterobacteriaceae family. The genus contains multiple serotypes, all of which are assumed to be pathogenic to humans. The normal habitat for Salmonella is the intestinal tract of many warm and cold-blooded animals, including humans. The bacterium can survive for prolonged periods outside an animal host and are most known for presenting a risk to manufactured dry products such as powdered ingredients and dietary supplements. Contamination can occur through the use of contaminated ingredients or by cross contamination from the environment. Human illness (salmonellosis) is characterized by gastroenteritis symptoms such as fever, vomiting, diarrhea, abdominal cramps, and malaise. In severe cases, infection can be fatal¹.

Listeria monocytogenes

Listeria is a bacterial genus that is widespread in the environment. The genus contains several species but only one is considered harmful to humans, Listeria monocytogenes. L. monocytogenes can multiply in high-moisture foods to levels that are potentially harmful. It is very commonly found in food processing environments and can cross contaminate foods. Symptoms of human infection (listeriosis) can be very mild (headache or malaise) or very severe (meningitis). Death rates can be quite high (>20%), especially among high-risk consumers such as pregnant women and their fetuses, the elderly, and the immunocompromised².

Escherichia coli, O157:H7, O157, and STECs

Escherichia coli is a species of bacteria that belongs to the Enterobacteriaceae family. While most strains of E. coli are not harmful to humans, a few strains can be pathogenic. The normal habitat of E. coli is the intestinal tract of warm-blooded animals, including humans. Because of the association with animals, foods of animal origin or foods and ingredients that come in contact with animal feces can be contaminated. Symptoms of pathogenic bacterial infection are typical of gastroenteritis, such as fever, vomiting, abdominal pain, and fever. In severe cases, a blood infection can lead to kidney failure and death³.

Staphylococcus aureus

Staphylococcus (Staph) is a species of bacteria that is commonly found on human skin. Like other pathogens, it is not always dangerous, but in the right conditions can be very harmful. The intestinal illness association with Staph is caused by bacterial toxins that cannot always be killed with heat. Symptoms of Staph food poisoning include nausea, cramps, and a severe upset stomach. These infections are rarely fatal, and are treated with lots of fluid to offset potential dehydration⁴.

Campylobacter species

Campylobacter infections typically result from sick poultry and meat and can spread to produce through contact with contaminated soil or feces. A Campylobacter infection typically involves diarrhea, fever, and vomiting and can last for up to a week. Most often, symptoms resolve themselves, but they can be fatal for immunocompromised individuals⁵.

Bacillus cereus

Similar to Staph, B. cereus infections are caused by bacterial toxins. These bacteria grow rapidly in improper food storage conditions and is often resistant to heat. B. cereus is very common in soils and is found in the majority of food-growing environments. It can grow and produce toxins in a variety of foods, including pasta, produce, sauces, and rice. Symptoms include vomiting, diarrhea, and nausea and last between 6-24 hours⁶.

Shigella species

There are four species of Shigella: S. sonnei, S. boydii, S. dysenteriae, and S. flexneri, with S. sonnei being the most common in the US. For the most part, infection resolves itself within a week, but in some cases, especially S. dysenteriae infections, there can be fatal complications. Bacteria can spread though water or on solids, and are commonly associated with poor sanitation conditions in food preparation areas⁷.

Clostridium perfringens

C. perfringens is one of the most common causes of food poisoning in the US. These bacteria produce spores which can survive in a range of environments for extended periods of time, meaning improper processing conditions can lead to the bacteria’s survival⁸.

Cronobacter sakazakii

C. sakazakii in infant formula is a leading cause of infant sickness. In addition to infant formula, C. sakazakii is found in other powdered dairy products, powdered starches, and dried herbs. For adults, infection is rarely fatal, but in infants can lead to sepsis and meningitis. Early symptoms include a fever, low energy, and poor feeding. These bacteria are common in the environment, so can be introduced to products via contaminated raw ingredients of contaminated surfaces⁹.

WHAT ARE COMMON TESTING POSSIBILITIES FOR FOOD PATHOGENS?

Clients may choose from several advanced detection platforms based on molecular or classical techniques.

PCR by Eurofins BACGene
PCR by BAX^®
VIDAS^®
Molecular Detection System (MDS)
Veriflow^®
Loop-Mediated Isothermal Amplification (LAMP)
Traditional Cultural

The main three pathogen testing methods performed at Eurofins are described below:

BACGene

BACGene is a PCR-based approach to pathogen testing, including Salmonella and E. coli, which was developed by Eurofins network of laboratories. There is not much difference between BACGene and other PCR methods (like BAX^®). Essentially, samples are prepared with specific lysis buffers and PCR mixes, and if present the bacterial DNA will amplify during PCR. Then, the amplified DNA is detected and quantified, allowing determination of pathogen contamination. Since BACGene is a Eurofins product, labs within the company avoid potential supply chain issues, have improved turnaround times (TAT), and overall lower prices.

Enteric Pathogen Risk Indicator (EPRI™)

Enteric Pathogen Risk Indicator (EPRI™) test is a compliment to the BACGene PCR testing, but can be performed independently as a rapid approach to risk identification and management. Ultimately, EPRI™ is an indicator test uniquely designed to find closer correlation with Salmonella and Shiga toxigenic E. coli presence without being a conclusive pathogen test and provides a rapid option to screen for both STEC and Salmonella in one PCR assay. It can also be combined with traditional cultural conformation assays for a comprehensive approach to testing. EPRI™ has been validated to detect 119 different Salmonella strains as well as 50 different STECs including E. coli O157 and the top 6 serogroups.

Traditional Cultural Methods

Culture based methods are very reliable and often the best choice for the most accurate results. However, they tend to not be the first choice in today’s testing environment as they often have a slower TAT. With these methods, samples are prepared and place on a plate or in a liquid solution of media specific to the target microbe. The media can either allow only the growth of a certain species (E. coli, for example) or has nutrient constraints to prevent growth of other bacteria. Growth can be visually accessed or quantified via spectrometry approaches.

Contact Eurofins for specific questions related to pathogens associated with your food or production process.

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