The spread of foodborne pathogens like Salmonella<\/i> remains a significant global health challenge. These microorganisms cause millions of infections annually, and more than half of the world’s food intoxications are linked to them. Accordingly, timely detection is essential to halt the spread of these bacteria and reduce infection cases. To this end, a new study tested a PCR method that can detect Salmonella<\/i> in food products in less than 7 hours. Current standard diagnostic methods require 5 or more days, which significantly slows down the recall of contaminated products from the market and directly increases the risk of an epidemic outbreak.<\/p>\n
Why Does Salmonella<\/i> Pose a Serious Threat?<\/strong><\/p>\n Salmonella<\/i> predominantly resides in the intestinal tract of animals and reaches humans through the consumption of contaminated food products\u2014meat, eggs, vegetables, milk, and seafood.<\/p>\n Salmonellosis is recognized as the second most common zoonotic disease (an infectious disease transferable from animal to animal, or to human and vice-versa) in the European Union. According to official data from 2023, 77,486 cases were reported, corresponding to an infection rate of 18 per 100,000 inhabitants. The most commonly detected serovars clinically are S. Enteritidis<\/i>, S. Typhimurium<\/i>, and monophasic S. Typhimurium<\/i>.<\/p>\n The infection manifests with the following clinical signs: nausea, abdominal pain, vomiting, and diarrhea. Although the majority of patients fully recover, children under 5 years old, the elderly, and immunocompromised individuals face a high risk of life-threatening complications. Poor hygiene conditions throughout the food chain\u2014from farm to final consumer\u2014contribute to bacterial contamination.<\/p>\n EU regulations (Reg. EC 2073\/2005<\/a>) strictly require zero tolerance for Salmonella<\/i> in high-risk food products(e.g., minced meat, dairy products, ready-to-eat vegetables, and mollusks). However, the currently operational standard diagnostic methodology (ISO 6579-1:2017<\/a>) requires a multi-day procedure that includes pre-enrichment, selective growth, plating, and final confirmation.<\/p>\n The Rapid PCR Method<\/strong><\/p>\n Researchers tested the new method on leafy greens, minced meat, buffalo mozzarella, and mussels. Both low (1\u201310 CFU\/25g) and high (10\u2013100 CFU\/25g) contamination levels of S. Typhimurium<\/i> were used for testing.<\/p>\n Bacterial DNA Extraction: Two inexpensive and fast methods were compared: simple boiling of the sample and the use of the specialized Chelex-100 reagent. Both methods ensure the rapid isolation of bacterial DNA.<\/p>\n Bacterial Proliferation (Enrichment Phase): The researchers checked which culture medium (BPW – Buffered Peptone Water) better accelerated Salmonella<\/i> growth. They compared a standard medium and a special capsule-enhanced medium.<\/p>\n Temperature Effect: The standard incubation temperature (3<\/span>7\u2218<\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span>C<\/span><\/span><\/span><\/span><\/span><\/span>) and a slightly higher, selective temperature (4<\/span>2\u2218<\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span>C<\/span><\/span><\/span><\/span><\/span><\/span>) that promotes Salmonella<\/i> growth were evaluated.<\/p>\n Pre-preparation of the Medium: Researchers significantly accelerated the process by pre-heating the BPW medium overnight at 41.<\/span>5\u2218<\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span>C<\/span><\/span><\/span><\/span><\/span><\/span>.<\/p>\n