Clostridium Testing

Clostridium is a genus of gram-positive and rod-shaped bacteria and this genus includes several significant human pathogens. It is obligate anaerobic and capable to produce endospores. The normal form of Clostridium is vegetative reproducing form. Clostridium perfringens is a spore-producing pathogen that belongs to the genus Clostridium.

Figure 1. Electron micrograph of Clostridium perfringens and related contaminated foods

Clostridium perfringens is found in many environmental conditions and the intestines of animals and humans. Clostridium perfringens contamination is often associated with raw poultry and meat. Other common sources of Clostridium perfringens infections include gravies, dried foods and pre-cooked foods, especially food that are kept warm after preparation for a long time before serving. It can multiply very fast under optimal growth conditions with little or no oxygen. Some strains of Clostridium perfringens cause illness by forming a toxin in the intestine. The common way that people get illness caused by Clostridium perfringens is usually from the consumption of foods that are contaminated with large number of Clostridium perfringens bacteria to produce enough toxins in the intestines. Clostridium perfringens can survive high temperatures. Spores that survive cooking process may germinate and grow rapidly in foods. Foods should be cooked to the correct temperature and kept at appropriate temperature to prevent the growth of Clostridium perfringens spores. Clostridium perfringens cells are inactivated when foods are frozen or stored at refrigeration conditions.

The symptoms of Clostridium perfringens infection include abdominal cramps and diarrhea within several hours after the consumption of contaminated foods. The illness generally starts suddenly and lasts for less than 24 hours. Young children and elderly people are more susceptible to Clostridium perfringens infection and may experience more severe symptoms.

The foods or culinary preparations that cause the majority of food poisoning typically contain at least 10⁴ CFU/g live vegetative forms of enterotoxigenic Clostridium perfringens. There is possibility that vegetative cells can multiply in the small intestine of the host, sporulate and produce enterotoxin. The contaminated foods do not contain preformed enterotoxins because Clostridium perfringens does not usually sporulate during culinary preparations. When the bacteria level is above 10⁴ CFU/g in the food sample, the food is considered as potentially hazardous to cause foodborne illness after the consumption of foods. The key factors that are responsible for the change of the level of Clostridium perfringens contamination are cooking conditions and subsequent storage of prepared foods.

Clostridium perfringens Testing of Food at Alfa Chemistry

The standard methods (EN/ISO and FDA BAM) that have been widely used to quantify Clostridium perfringens are culture-based methods using general microbiological testing supplies. Selective or differential mediums are used to incubate Clostridium perfringens for appropriate time followed by the plate counting technique to determine the contamination level of Clostridium perfringens. Plating method for Clostridium perfringens uses solid medium of Tryptose-sulfite-cycloserine (TSC) agar. Presumptive confirmation test is performed using biochemical identification technique after enumeration.

Alfa Chemistry offer accurate and validated testing platforms for the enumeration and identification of Clostridium perfringens in various food samples to meet customers' needs. We also have experience working on different standards and regulations.

Platform: Plate counting technique

Limit of detection: 10 CFU/g

Sample type: Solid and liquid food samples

Sample size: 25 g