Enterobacteriaceae Testing

Enterobacteriaceae (EB) are a large family of different types of gram-negative bacteria including more than 30 genera and over 100 species. Enterobacteriaceae include many harmless generic coliform and E. coli subgroups as well as some familiar pathogens such as Salmonella, Shigella, and hemorrhagic E. coli.

Figure 1. Electron micrograph of Enterobacteriaceae and related contaminated foods

Many members of Enterobacteriaceae are harmless and may be prevalent in certain industrial environment. Enterobacteriaceae are commonly found in feces of humans and animals. Enterobacteriaceae can be used as important indicators of the hygiene and sanitation of the production facility, and of post-processing contamination of heat processed foods in the food industry. Enterobacteriaceae are easy to enter the food chain due to their ubiquitous distribution. The testing of indicator bacteria like Enterobacteriaceae is useful to monitor broad range of commonly found microbes in the foods and environment. Some pathogenic bacteria can be hard to find and detect because many kinds of pathogenic bacteria are typically present in the environment at very low levels. Enterobacteriaceae have been used in the poultry indicator testing to broadly search and identify the relatives to pathogens that may be present in the food production process such as Salmonella.

The testing of more prevalent and common generic indicator bacteria is necessary to show the existed conditions for pathogenic bacteria to grow. The contamination of Enterobacteriaceae including pathogens must be controlled or prevented along the food supply chain through the application of the acknowledged quality assurance systems. Enterobacteriaceae are heat-sensitive, so proper cooking or pasteurization is commonly performed to prevent biological hazards in finished products. Product samples are tested for Enterobacteriaceae to verify the performance of the heat treatment.

The presence of Enterobacteriaceae in ready-to-eat foods with high numbers (>10⁴ CFU/g) indicates that an unacceptable level of contamination in food samples. The level of Enterobacteriaceae less than 10² CFU/g is normally regarded as satisfactory. Their presence in heat treated food also indicates the possibility of under-processing or inadequate cooking of the foods. Some members of Enterobacteriaceae can contribute to the formation of histamine in foods if the foods are not process properly. Testing for Enterobacteriaceae is not usually applied to fresh produce and fruits. Indicator bacteria like Enterobacteriaceae are common bacteria to provide indirect warnings to the possibility of the present of more hazardous bacteria.

Enterobacteriaceae Testing of Food at Alfa Chemistry

The standard methods (EN/ISO and AOAC) that have been widely used to quantify Enterobacteriaceae are culture-based methods using general microbiological testing supplies. Selective mediums or Petrifilm dry rehydratable film are used to incubate Enterobacteriaceae for appropriate time followed by the plate counting technique to determine the level of Enterobacteriaceae in the sample. Confirmation test is performed using biochemical identification technique after the enumeration. We also have expertise in the sample preparation of a variety types of food matrices.

We offer accurate and validated testing platforms for the enumeration and confirmation of Enterobacteriaceae 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