FREQUENCY AND ANTIBACTERIAL RESISTANCE OF LISTERIA SPP. ISOLATED FROM THE FOOD AND ENVIRONMENTAL SAMPLES IN URMIA

Genus Listeria especially Listeria monocytogenes (L.monocytogenes), as a foodborne
pathogen, is the causative agent of Listeriosis that could be fatal in high risk subjects such as
pregnant women, immunocompromised persons, neonates, and elderly.
Materials & Methods: In the present study, the frequency of Listeria spp. and L.monocytogenes in 277
food and environmental samples from retail food markets of Urmia city was evaluated. After isolation
and identification of strains, their antimicrobial resistance to 8 antibiotics of isolates was investigated
by Kirby – bauer method.
Results: Out of 277 samples, 10 (3.61%) were positive for presence of Listeria spp. based on the
polymerase chain reaction (PCR). Of 10 isolates, 3 (1.08%) isolates were identified as L.monocytogenes
and molecular confirmation was done by PCR for plc-A gene. The frequencies of other species were
L.ivanovii (0.72%), L.siligerii (0.72%) and 0.36% for welchimeri, grayi and innocua species,
respectively (. Eight of the isolates (80%) were resistant to ampicillin and 7 (70%) to penicillin G. Their
resistance to Co-trimoxazole and Gentamicin was not seen among isolates. Besides that, the resistance
rate to erythromycin, rifampin, and tetracycline was 20%, for each antibiotic.
Conclusion: The result of present study indicated the resistance of Listeria species isolated from food
against antibacterial agents that are therapeutic choice for Listeriosis. This reveals the prompt need for
surveillance program and information system setup about listeria in Iran