Microbial and Parasitic Contamination of Fresh Raw Vegetable Samples and Detection of the BlaTEM and BlaCTX-M Genes from E. coli Isolates

Alina Ghimire,Tirtha Raj Bajgai,Tulsi Nayaju,Dhiraj Kumar Chaudhary,Vijaya Raghavan,Jitendra Upadhyaya,Bhoj Raj Pant,Milan Kumar Upreti,Binod Lekhak,Niranjan Koirala

doi:10.3390/agriculture10080341

Abstract

A total of 100 fresh-raw vegetable samples were collected from the Kathmandu, Lalitpur and Bhaktapur districts of Nepal to evaluate microbial and parasitic contamination, presence of Extended Spectrum Beta Lactamase (ESBL)-producing Escherichia coli and detect the blaTEM and blaCTX-M genes among the Escherichia coli isolates. This study revealed that the prevalence of Giardia cysts was highest (100%) and Hookworm and Entamoeba coli were lowest (1% each). Coliforms were isolated from every raw vegetable sample. A total of 178 bacterial isolates were isolated among which 57 isolates were identified as E. coli, out of which 33 were Multi-drug resistant (MDR) isolates. The high rate of resistance was found towards amoxicillin/clavulanate, tetracycline and cotrimoxazole. The 10 E. coli isolates tested positive in an ESBL screening, out of which 4 were confirmed as ESBL producers by a combined disc test. Out of these 4 confirmed ESBL E. coli, one was found to carry both the blaTEM gene and blaCTX-M genes by the Polymerase Chain Reaction (PCR) technique. One isolate has only the blaTEM gene, while other isolate harboured only blaCTX-M genes.

Highlights

Vegetables like carrot, radish, cucumber, tomato, cabbage, lettuce, coriander, etc., can be consumed without heat treatment
The prevalence of Giardia cysts was found highest (100%) followed by Entamoeba histolytica (24%), The prevalence of Giardia cysts was found highest (100%) followed by Entamoeba histolytica
Out of 100 samples, almost all samples were heavily contaminated with high numbers of coliform bacteria and parasites

Summary

Introduction

Vegetables like carrot, radish, cucumber, tomato, cabbage, lettuce, coriander, etc., can be consumed without heat treatment. According to Beuchat et al [4], during harvesting fecal materials, human handling, harvesting equipment, transport containers, wild and domestic animals, air, transport vehicles, ice or water can contaminate vegetables. Another major cause of vegetable contamination could be the unavailability of hygienic irrigation water and proper knowledge. Since fruits and vegetables are essential parts of our food that are consumed raw or sometimes inadequately cooked, consumption of those fruits and vegetables can be the major route of transmission of human pathogens [5]

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Conclusion