The Centers for Disease Control and Prevention (CDC) report that Salmonella bacteria poisoning causes 1.35 million infections, 26,500 hospitalizations, and 420 deaths every year in the United States. When a salmonella outbreak occurs, being able to test patients quickly and accurately to detect specific bacteria types is imperative to public health.
Salmonella bacteria live in the intestines of animals and humans and are excreted in the feces. Humans can become infected when they drink contaminated food or water, especially undercooked meat, poultry, and eggs. The bacteria cause vomiting, stomach cramps, diarrhea, fever, and headache.
Researchers have now developed a specific assay to detect different Salmonella serotypes, which could lead to being able to quickly trace the source of the infection. The report appears in the Journal of Molecular Diagnostics.
According to Professor Ruiting Lan from the School of Biotechnology and Biomolecular Sciences at the University of New South Wales in Sydney Australia says, "Salmonella in a clinical or food sample may be present in very small amounts and thus requires very sensitive methods to detect them. Multiple cross-displacement amplification (MCDA) is a method that can detect very small amounts of DNA rapidly and is also performed at a single constant temperature, in contrast to the cycling of temperatures required in other methods such as PCR. This makes it a good fit for a simple, rapid, and sensitive bacterial detection test. Although an MCDA test for any Salmonella already exists, it does not distinguish between different serotypes.”
The scientists developed an MCDA assay for each of the seven subtypes of Salmonella. All the assays produced results in about eight minutes and don’t require any specialized equipment, which will make it easier to test in a variety of settings. "The assays developed in this study are unique because the gene markers used were selected based on analyzing thousands of genomes. Thus, these markers future proof Salmonella serotyping in the era of culture-independent diagnostic testing," says Lan.
The conventional method of determining Salmonella types is growing them from samples and then testing. The new MCDA test is faster, and the bacteria doesn’t have to be grown in a culture.