Prevalence and Antibiotic Susceptibility of Listeria Monocytogenes Isolated from Retail Ready-to-Eat Meat Products in Gorgan, Iran

Background and Objectives: Listeria monocytogenes are known as an emerged foodborne pathogen and considered as a severe health risk. In the present study, prevalence and antibiotic resistance of L. monocytogenes isolated from ready-to-eat meat products in Iran were assessed. Materials and Methods: A total of 200 ready-to-eat meat products, including chicken meat (wing, breast, and leg), lamb and fish, were collected, and L. monocytogenes was isolated according to ISO 11290–1. All of the isolates were verified using polymerase chain reaction and serotyping methods. Antibiotics susceptibility of L. monocytogenes isolates was assessed using the broth microdilution method. Results: The presence of L. monocytogenes was verified in 13% of the samples. The presence of L. monocytogenes was reported in 26% of roast chicken meat, 5% of roast fish and 8.33% of cooked beef. Serology showed that Serotype 1/2a (48.13%) was the dominant serotype, followed by 4b (38.4%), 1/2c (6.99%) and 1/2b (6.48%). The result showed that 37 out of 100 L. monocytogenes isolates were resistant to all tested antibiotics. Furthermore, eight isolates were intermediately multi-resistant to the antibiotics. The rate of antibiotic resistance in L. monocytogenes was 52% in Serotype 1/2a, 39% in Serotype 4b, and 35% in Serotype 1/2c. Isolates of L. monocytogenes were mostly resistant to penicillin, ampicillin and erythromycin, but highly susceptible to tetracycline and gentamycin. Conclusions: The high level of L. monocytogenes prevalence and its resistance to antibacterial agents in meat products may result in severe human listeriosis. Therefore, it is necessary to use efficient monitoring protocols for antibiotic administration and further safety management systems in food production units.