Microbiological Quality of Ready-to-Eat Vegetables Collected in Mexico City: Occurrence of Aerobic-Mesophilic Bacteria, Fecal Coliforms, and Potentially Pathogenic Nontuberculous Mycobacteria

Jorge Francisco Cerna-Cortes,Nancy Leon-Montes,Sandra Rivera-Gutierrez,Ana Laura Cortes-Cueto,Laura P Salas-Rangel,Addy Cecilia Helguera-Repetto,Jorge Alberto Gonzalez-Y-Merchand,Elizabeth Fernandez-Rendon,Daniel Lopez-Hernandez

doi:10.1155/2015/789508

Abstract

The aims of this study were to evaluate the microbiological quality and the occurrence of nontuberculous mycobacteria (NTM) in a variety of salads and sprouts from supermarkets and street vendors in Mexico City. Aerobic-mesophilic bacteria (AMB) were present in 100% of RTE-salads samples; 59% of samples were outside guidelines range (>5.17 log10 CFU per g). Although fecal coliforms (FC) were present in 32% of samples, only 8% of them exceeded the permissible limit (100 MPN/g). Regarding the 100 RTE-sprouts, all samples were also positive for AMB and total coliforms (TC) and 69% for FC. Seven NTM species were recovered from 7 salad samples; they included three M. fortuitum, two M. chelonae, one M. mucogenicum, and one M. sp. Twelve RTE-sprouts samples harbored NTM, which were identified as M. porcinum (five), M. abscessus (two), M. gordonae (two), M. mucogenicum (two), and M. avium complex (one). Most RTE-salads and RTE-sprouts had unsatisfactory microbiological quality and some harbored NTM associated with illness. No correlation between the presence of coliforms and NTM was found. Overall, these results suggest that RTE-salads and RTE-sprouts might function as vehicles for NTM transmission in humans; hence, proper handling and treatment before consumption of such products might be recommendable.

Highlights

According to the definition given by the FAO and the WHO [1], ready-to-eat (RTE) foods include any comestible that is normally consumed in its raw state
Aerobic-mesophilic bacteria (AMB) and total coliforms (TC) were present in 100% of RTE-sprouts samples analyzed (Table 1); fecal coliforms (FC) were present in 69% of samples
The median concentration of FC was significantly lower in RTE-sprouts from SPM (3.3 most probable number (MPN)/g) than the one found in street-vendor stalls (SVS) (23.5 MPN/g) (P = 0.007)

Summary

Introduction

According to the definition given by the FAO and the WHO [1], ready-to-eat (RTE) foods include any comestible that is normally consumed in its raw state. Demand for RTE food has led to an increase in the amount and selection of different products available for the consumers [2]. As well as being considered low-calorie food, they are rich in fiber and provide a great variety of vitamins, minerals, and other phytochemicals [3]. Their consumption is encouraged in many countries by government health agencies to protect people against a range of illnesses such as cancer and cardiovascular diseases [4]. Continued increase in the consumption of fresh meals has occurred

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