MOLECULAR DETECTION OF LISTERIA MONOCYTOGENES IN FRESH VEGETABLES VIA RT-PCR IN THE WEST BANK
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Date
2024-02-12
Authors
Al-Athamneh, Dania
Journal Title
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Publisher
An-Najah National University
Abstract
Listeria monocytogenes is an emerging foodborne pathogen that can be transmitted by a wide range of food items. This study aimed to evaluate the existence of L. monocytogenes in freshly selected vegetables (lettuce, parsley, watercress, spring onion, carrot juice) in five governorates in the West Bank, Palestine using both conventional and molecular methods. A total of 150 fresh vegetable samples were bought from hypermarkets and street food hawker stands. The presumed isolates were differentiated biochemically and were further confirmed by Real-Time Polymerase Chain Reaction (RT-PCR) targeting 16S rRNA gene for Listeria spp. and the hly gene, which is specific to L. monocytogenes. The results showed that 71% of the examined fresh vegetable were positive for L. monocytogenes based on the media's selectivity and the colonies' morphological characteristics. Percentages distribution of L. monocytogenes in the fresh vegetables were 66%, 70, 70, 73 and 73% for lettuce, watercress, spring onion, carrot juice, and parsley, respectively. On the other hand, statistical analysis of RT-PCR results indicated significant differences in L. monocytogenes levels among vegetable samples within the same governorate. In Tulkarm, the highest levels were found in carrot juice, while the lowest were in lettuce. Also in Nablus, the highest levels were found in carrots juice, while the lowest were in lettuce and watercress. Also, Ramallah, Bethlehem, and Hebron, each the highest in spring onion, while the lowest were lettuce. Additionally, indicated comparison of L. monocytogenes levels across cities for selected of vegetables significant differences that lettuce had the highest prevalence in Bethlehem, parsley in Bethlehem, also watercress, spring onion, carrot juice each the highest in Hebron. In conclusion, this study has demonstrated a high prevalence of Listeria in fresh vegetables using both methods however, the molecular method was more sensitive and reliable for listeria confirmation. Contamination by Listeria in hypermarkets and street food as well is of great public concern and justifies more observation and strict regulations to reduce the frequent contamination of fresh vegetables with L. monocytogenes.