Scientists have shown the presence of multidrug-resistant strains of Listeria monocytogenes in frozen burger patties taken from supermarkets and other retail shops in Malaysia.
Although the bugs-in-burgers research showed that the overall incidence of antibiotic resistance in L. monocytogenes was low, it was also found that some of the bacterial strains isolated from the burgers were resistant to the types of antibiotics commonly used in veterinary and human therapy.
The bacterium L. monocytogenes can cause the disease listeriosis when ingested. Symptoms for this disease range from gastrointestinal upset to headaches, fever and, in the most severe cases, blood poisoning. Those at highest risk include pregnant women, babies and the elderly.
Drug resistant Listeria is relatively new, compared with other bacteria such as those associated with hospital infections, and cases only date back to around 1988.
From an examination of raw burger patties, the researchers found that the most common form of antibiotic resistance was tetracycline resistance, followed by erythromycin resistance. Provided that burgers are cooked correctly there is no risk from such bacteria. Listeria is generally a risk for raw food or unpasteurized dairy products.
It is not only meat burgers that can become infected with Listera. A month ago, Costco had to recall a range of veggie burgers throughout the U.S.
The research into antibiotic resistant Listeria was published in Pertanika Journal of Tropical Agricultural Science.