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

Abstract EN

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.