BackgroundNontuberculous mycobacteria (NTM) are environmental opportunistic pathogens found in natural and human-engineered waters, including drinking water distribution systems and household plumbing. This pilot study examined the frequency of occurrence of NTM in household potable water samples in Mexico City. Potable water samples were collected from the “main house faucet” and kitchen faucet. The presence of aerobic-mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC) and NTM species were determined. Mycobacteria species were identified by PCR restriction enzyme pattern analysis (PRA) of the 65-kDa heat shock protein gene (hsp65) and sequencing of the hypervariable region 2 (V2) of the 16S rRNA gene and of the rpoB gene.ResultsAMB (<100 CFU/ml) were present in 118 out of 120 samples; only two samples were outside guidelines ranges (>100 CFU/ml). TC and FC were detected in four and one samples, respectively. NTM species were recovered from 16% samples (19/120) and included M. mucogenicum (nine), M. porcinum (three), M. avium (three), M. gordonae (one), M. cosmeticum (one), M. fortuitum (one), and Mycobacterium sp (one). All household water samples that contained NTM complied with the standards required to grade the water as “good quality” potable water.ConclusionHousehold potable water may be a potential source of NTM infection in Mexico City.

This study evaluated the microbiological quality and prevalence of Escherichia coli and diarrheagenic E. coli pathotypes (DEP) among fresh-squeezed orange juice from street vendors and their hygienic practices. Sixty orange juice stalls in Mexico City were visited, and 60 samples were purchased. Most (65%) of the street vendors had poor hygienic practices. Twelve (20%) prepared orange juice at the time of purchase, while the other stalls sold already-squeezed orange juice. All samples analyzed were positive for aerobic mesophilic bacteria, with limits ranging from 1 to 6.8 log CFU/mL. A total of 35 (58.3%), 27 (45%), and 5 (8.3%) samples were positive for total coliforms, fecal coliforms, and E. coli, respectively, present at concentrations ranging from < 3 to > 1100, < 3 to > 1100, and < 3 to 53 MPN/mL, respectively. Two samples harbored DEP at concentrations of 3.6 and 9.2 MPN/mL. Both samples harbored Shiga toxin-producing E. coli strains, positive for the Shiga toxin 2 (stx2) locus. Our results suggest that consumption of fresh-squeezed street-vended orange juice may pose a health risk for consumers, revealing the necessity to implement adequate hygiene and safety practices to protect the health of consumers.