AN EVALUATION OF LISTERIA MONOCYTOGENES PREVALENCE IN FRESH VEGETABLES COLLECTED FROM GREENGROCERS IN BIRJAND IN 1396

Background and Aim:Listeria monocytogenes is an important opportunistic and zoonotic and food pathogen causing meningitis and septicemia in infants, people with immune deficiency, and pregnants. This species is highly resistant to frost, dryness and osmotic stress and can easily grow in fresh vegetables causing contamination. The aim of this study was to investigate the prevalence of Listeria monocytogenes in fresh vegetables in Birjand.Methods:A total of 100 samples of vegetables were randomly selected from different greengrocers in Birjand. Each sample was initially placed in LEM medium for 48 hours. Then 100 μl of inoculated LEM was transferred to selective Palm medium and incubated at 37°C for 48 hours. Grown colonies were examined morphologically and black colonies were considered as probable positive cases. Then the colony was examined by further experiments including gram staining, hemolysis, catalase and motility. All suspected isolates were conducted molecular multiplex PCR and by using to pairs of specific primers the genus of Listeria and the species of monocytogenes was confirmed.Results:Of 100 samples of vegetable, 11 samples were suspected to Listeria in the first stage. After PCR, all cases were detected as Listeria and 7 samples were confirmed as Listeria monocytogenes.Conclusion:The present study revealed that the prevalence of listeria monocytogenes in fresh vegetables in Birjand is about 7%. As this level of prevalence is remarkably high, it is strongly recommended to disinfect and thoroughly wash the vegetables before use.

Keywords:

Listeria monocytogenes , vegetables , Prevalence , Birjand