Campylobacter organisms are spiral-shaped, gram-negative bacteria that can cause disease in humans and animals. It is one of the most common causes of diarrheal illness in the United States. Most human illness is caused by one species, Campylobacter jejuni. The most frequently reported cases of Campylobacter are associated with eating raw or undercooked poultry or from cross-contamination of other foods by these items. Reports of other outbreaks have been linked to unpasteurized milk or contaminated water. Strains are sensitive to oxygen and are considered fragile, making it difficult to cultivate and maintain. Confirmation of Campylobacter requires microscopic, biochemical, and immunological techniques that are tedious and labor intensive.
Cronobacter can be found in the environment, hospital, infant nutritional formula and homes. Cronobacter can cause severe bacterial sepsis or meningitis in infants.
E. coli O157:H7
E. coli serotype O157:H7 is a gram-negative, rod-shaped bacterium and a cause of foodborne illnesses. Infection often causes severe hemorrhagic diarrhea and stomach cramping, with little to no fever. Outbreaks have been associated with such foods as: undercooked beef, raw milk, unpasteurized juices, and raw produce. Transmission can also occur person-to-person or by coming into contact with contaminated water sources. The challenge of testing for this specific pathogen is the low level of its occurrence relative to other organisms in the sample. Enrichment and isolation media are not generally selective enough. Both factors make cultural identification and confirmation very difficult.
This bacterial genus includes the pathogen Listeria monocytogenes, as well as, six non-pathogenic species (L. grayi, L. inocua, L. ivanovii, L. seeligeri, and L. welshimeri). Preventing contamination of products with L. monocytogenes requires effective sanitation of food contact and non-contact surfaces in the manufacturing environment. Monitoring the environment for the presence of all Listeria spp. helps to ensure that the sanitation program is effective and will prevent the establishment of L. monocytogenes in the plant.
Listeriosis is a very serious disease for humans with an overt mortality rate of about 20 percent. This gram-positive pathogen has been found in uncooked meats and vegetables, pasteurized and unpasteurized milk, and ready-to-eat foods, such as hot dogs and deli meats. Preventing Listeria requires effective sanitation of food contact surfaces.
Salmonella is the most frequently reported cause of foodborne illness. These gram-negative, rod-shaped bacilli can cause diarrhea, vomiting, fever, chills, and cramps and are especially dangerous to the elderly and infants. A variety of raw and unprocessed foods have been found to carry Salmonella spp., such as: raw meat, poultry and eggs, shellfish, and in such fruits as: watermelon and cantaloupe. There are over 2,000 serotypes in the Salmonella family and all strains and species are pathogenic to humans. In order to identify and isolate the many serotypes from other closely related bacteria, a test must be able to cover all serovars of Salmonella without detecting other closely related bacteria — a very delicate balancing act.
Shiga Toxin Genes
Shiga toxin (stx), also known as verotoxin, is a toxin generated by some strains of Escherichia coli and is a critical virulence factor in Enterohemorrhagic E. coli. Shiga toxin producing E. coli (STEC) can cause illness ranging from intestinal disease to severe kidney complication and hemolytic uremic syndrome (HUS). Regulatory agencies, including the USDA, have defined Non O157 STEC by the presence of Shiga toxin (stx) and intimin (eae) genes associated with specific O serogroups.
Staphylococcal enterotoxin is a common cause of food poisoning. This results from the ingestion of Staphylococcal enterotoxins (SET) produced by toxigenic strains of Staphylococcus aureus. Foods often associated with outbreaks include meat and poultry, eggs, mixed salads, cream-based pastries, and milk and dairy products. Staphylococcus aureus can easily be destroyed by heat treatment, however, SET has almost total resistance to dehydration, proteolytic enzymes, and heat treatment. Traditional detection methods are costly, tedious, and lack the level of sensitivity required for industrial use.
STEC (Shiga Toxigenic E. coli)
Non-O157 Shiga toxin-producing Escherichia coli (STEC) is a type of enterohemorrhagic E. coli bacteria that can cause illnesses ranging from mild intestinal disease to severe kidney complications. Causes and outbreaks of STEC have been associated with undercooked beef, raw milk, unpasteurized juices, red leaf lettuce, alfalfa sprouts, and contaminated water. The highest infection rate in humans occurs in children under five years of age and elderly patients. The USDA FSIS’s definition of the Top Six non-O157 STEC includes both an immunological and genetic component of specific pathogenicity genes. Therefore, rapid methods employing only a single detection technology will likely generate a high frequency of false positives.