Characterization of Gene Families Encoding Beta-Lactamases of Gram-Negative Rods Isolated from Ready-to-Eat Vegetables in Mexico City.

Beta-lactam resistant bacteria, which are commonly resident in tertiary hospitals, have emerged as a worldwide health problem because of ready-to-eat vegetable intake. We aimed to characterize the genes that provide resistance to beta-lactam antibiotics in Enterobacteriaceae, isolated from five commercial salad brands for human consumption in Mexico City. In total, twenty-five samples were collected, grown in blood agar plates, and the bacteria were biochemistry identified and antimicrobial susceptibility testing was done. The carried family genes were identified by endpoint PCR and the specific genes were confirmed with whole genome sequencing (WGS) by Next Generation Sequencing (NGS). Twelve positive cultures were identified and their microbiological distribution was as follows: 8.3% for ( = 1), 8.3% for ( = 1), 16.7% for ( = 2), 16.7% for ( = 2), and 50% ( = 6) for . The endpoint PCR results showed 11 colonies positive for BIL (91.7%), 11 for SHV (91.7%), 11 for CTX (97.7%), 12 for DHA (100%), four for VIM (33.3%), two for OXA (16.7%), two for IMP (16.7%), one for KPC (8.3%), and one for TEM (8.3%) gen; all samples were negative for ROB, CMY, P, CFX and LAP gene. The sequencing analysis revealed a specific genotype for (blaSHV-12, blaCTX-M-15, blaDHA-1, blaKPC-2); (blaSHV-1, blaCTX-M-3, blaDHA-1, blaVIM-2); (blaSHV-12, blaCTX-M-15, blaDHA-1); (blaSHV-12, blaVIM-1, blaDHA-1); and, (blaSHV-1, blaCTX-M-1, blaDHA-1, blaVIM-2, blaOXA-9). Our results indicate that beta-lactam-resistant bacteria have acquired integrons with a different number of genes that provide pan-resistance to beta-lactam antibiotics, including penicillins, oxacillins, cefalosporins, monobactams, carbapenems, and imipenems.