Phenotypic and Genotypic Characteristics of Listeria monocytogenes Isolated From Dairy and Meat Products

Background: Listeria monocytogenes is a foodborne pathogen and a serious threat to the public health in the world. Consumption of traditional foods such as dairy and meat products can be a major reason for relative abundance and isolation of these bacteria. Objectives: The purpose of this study was to determine the phenotypic and genotypic characteristics of L. monocytogenes strains isolated from dairy and meat products. Materials and Methods: A total of 317 dairy products and meat-processed samples were collected. Antibiotic susceptibility test was performed on each sample by the disk diffusion method (Kirby Bauer). Five reference loci were used for typing of L. monocytogenes strains by MLVA (Multiple Locus VNTR Analysis) Technique. Results: A total of 24 L. monocytogenes isolates were collected from the dairy and meat products. Resistance of isolated L. monocytogenes strains to penicillin G were 54.54% (from dairy products) and 46.15% (from processed meat). Genetic relatedness of isolates were assessed by MLVA. Out of 13 different types, type 2 with 6 strains and type 3 with 4 strains, were the most common types. Conclusions: MLVA analysis showed that samples obtained from different sources could have similar genetic profile. As a result, administration of penicillin in patients with listeriosis (especially pregnant women) and antibiotic susceptibility test are recommended. The fast and accurate methods such as MLVA for tracking of pollution sources of L. monocytogenes are recommended during outbreaks.