ISOLATION, PURIFICATION AND IDENTIFICATION OF SOME MULTI-DRUG RESISTANT FOOD-BORNE PATHOGENS IN LEBANESE FRESH PRODUCE

Abstract

Fresh produce can be a vehicle for the transmission of multi drug resistant pathogens capable of causing human illnesses and some of them can grow on fresh-cut vegetables. The present study was designed to monitor the occurrence of Esherichia coli, Salmonella and Listeria monocytogenes, in Lebanese fresh produce with the possibility of reducing the contamination using acetic acid and sodium chloride at5°C as dressing sauce and 22°C as a washing solution. A total of about 145 samples of conventional and organic fresh produce were collected from different 10 agricultural fields, 14 grocery stores and 7 market places in Lebanon from north to south areas (during June through December 2013). Salmonella and Listeria monocytogenes were not detected in all the collected samples, however 26.8% of produce items were positive for non-O157:H7 E.coli, the highest contamination with fecal E. coli occurred in leafy green produce (purslane, thyme, parsley and lettuce) except peppermint items were fecal E. coli free . The transition from pre-harvest to post-harvest stage showed an increase in fecal contamination load whereas in farms the prevalence of E. coli was 25.7 % and became 52.9% in market place. However organic fresh produce showed the lowest load in coliform counts and prevalence of E. coli. A total of 23% E. coli isolates are considered to be multidrug resistant since they showed resistance to ≥ 3antibiotic classes (β-lactam, tetracycline and folate inhibitor). It was revealed that 2g of sodium chloride results in a survival of MDR E. coli. A and may limit antibacterial effect of vinegar with low acidity (2% acetic acid) resulting in the reduction of 1.5 log10 CFU/ml after 20 min at room temperature , in contrast washing treatment solution with 4% acetic acid reduces 2.42 log10 CFU/ml within 10 min. Dressing sauce showed strong inhibition of inoculated Salmonella enteritidis after 3 hours of storage at 5±°C. On the other hand a total reduction of 0.2 and 3 log10 CFU/g were noticed with MDR E. coli A at zero time and after 3hrs respectively, where the total inhibition of MDR E. coli A was achieved after 6hrs of storage at 5±1°C.

Keywords: Identification, Isolation, Lebanese fresh produce, food-borne pathogens


Article Review Status: Published

Pages: 59-72 (Download PDF)

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