Salmonella Testing

The genus Salmonella is a group of gram-negative, rod-shaped, and non-spore forming bacteria of the family Enterobacteriaceae. It contains two species but more than 2600 serotypes. Salmonella is one of the most common pathogens to cause foodborne illness.

Figure 1. Electron micrograph of Salmonella and related contaminated foods

Salmonella food poisoning has continued to be an important global public health issue. Animals can carry Salmonella in their intestines and feces and act as primary reservoirs of Salmonella. Food and water supplies contaminated by fecal pollution is a major contribution to the ubiquity of Salmonella in the food supply chain. The bacteria is transmitted through contaminated foods. It can also be spread by food handlers who do not clean surfaces and tools during food preparation. Salmonella can contaminate a variety of foods including beef, chicken, eggs, produce, and even processed foods. During the past few years, foodborne outbreaks of Salmonella have been associated with contaminated chicken, eggs, and fresh produce such as pre-cut melon, cucumbers, and sprouts. Salmonella infection is typically caused by the consumption of contaminated foods. Salmonella is sensitive to heat and does not grow at refrigeration temperatures. But it may be resistant to dehydration and survive well in acid foods. It can be destroyed during the cooking process to a proper temperature.

Typical symptoms of Salmonella infection are stomach cramps, diarrhea, and fever. The illness usually lasts 4 ~ 7 days and people can recover without antibiotic treatment. Some people may need to be hospitalized with severe diarrhea. The elderly, very young children, and people with weakened immune systems are more susceptible to Salmonella infection.

There have been standards and regulations established to control the incidence of contamination of Salmonella. In most cases the monitoring of Salmonella is required by regulations. Low numbers of Salmonella may cause illness. The infective dose for vulnerable individuals could be as low as less than 10 CFU/g in some cases. The Microbiological Criteria Regulation in the EU and USA stated that the presence of Salmonella in 25 g sample is not acceptable for any ready-to-eat foods at the point of production.

Salmonella Testing of Food at Alfa Chemistry

There are standard methodology and alternative rapid methodologies (EN/ISO, AOAC and FDA BAM) that have been used for the isolation and detection of Salmonella from foods and environmental samples. Tradition detection methods are culture-based methods which may require long assay time. The AOAC database contains almost 40 products for the rapid detection of Salmonella. Rapid test kits that approved as AOAC with respective enrichment medium can be conditionally used for the screening of the presence of the contamination of Salmonella. The rapid test protocols include a step of selective enrichment culture and then apply rapid detection techniques to replace incubation on selective agars. The confirmation test is then performed using biochemical identification technique.

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

Platform: Rapid ELISA-based assays

Limit of detection: Qualitative test per sample size (negative/positive)

Sample type: Solid and liquid food samples

Sample size: 25 g