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High-Throughput 2018, 7(4), 36;

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

CICSA Facultad de Ciencias de la Salud Universidad Anáhuac Mexico Campus Norte, Huixquilucan, Estado de Mexico 52786, Mexico
Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de Mexico. Coyoacán, Ciudad de Mexico 04510, Mexico
Laboratorio de Investigaciones Químico-Clínicas, Facultad de Ciencias Químicas, Benemerita Universidad Autónoma de Puebla, San Manuel, Ciudad Universitaria, Puebla 72570, Mexico
Laboratorio de Medicina Genómica, Hospital Regional “Primero de Octubre”, ISSSTE, Av. Instituto Politécnico Nacional 1669, Lindavista, Gustavo A. Madero, Ciudad de Mexico 07300, Mexico
División de Investigación en Salud, Unidad Médica de Alta Especialidad (UMAE), Hospital de Especialidades, Centro Médico Nacional General de División “Manuel Ávila Camacho”, Instituto Mexicano del Seguro Social (IMSS), Puebla 72090, Mexico
Departamento de Fisiología Biofísica y Neurociencias, Centro de Investigación y Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, Gustavo A. Madero, Ciudad de Mexico 07360, Mexico
Author to whom correspondence should be addressed.
Received: 18 September 2018 / Revised: 1 October 2018 / Accepted: 7 November 2018 / Published: 23 November 2018
PDF [1202 KB, uploaded 23 November 2018]


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 Enterobacter aerogene (n = 1), 8.3% for Serratia fonticola (n = 1), 16.7% for Serratia marcesens (n = 2), 16.7% for Klebsiella pneumoniae (n = 2), and 50% (n = 6) for Enterobacter cloacae. The endpoint PCR results showed 11 colonies positive for blaBIL (91.7%), 11 for blaSHV (91.7%), 11 for blaCTX (97.7%), 12 for blaDHA (100%), four for blaVIM (33.3%), two for blaOXA (16.7%), two for blaIMP (16.7%), one for blaKPC (8.3%), and one for blaTEM (8.3%) gen; all samples were negative for blaROB, blaCMY, blaP, blaCFX and blaLAP gene. The sequencing analysis revealed a specific genotype for Enterobacter cloacae (blaSHV-12, blaCTX-M-15, blaDHA-1, blaKPC-2); Serratia marcescens (blaSHV-1, blaCTX-M-3, blaDHA-1, blaVIM-2); Klebsiella pneumoniae (blaSHV-12, blaCTX-M-15, blaDHA-1); Serratia fonticola (blaSHV-12, blaVIM-1, blaDHA-1); and, Enterobacter aerogene (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. View Full-Text
Keywords: Enterobacteriaceae; antibiotics; beta-lactamases; beta-lactam resistome; whole genome sequencing Enterobacteriaceae; antibiotics; beta-lactamases; beta-lactam resistome; whole genome sequencing

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Vázquez-López, R.; Solano-Gálvez, S.; León-Chávez, B.A.; Thompson-Bonilla, M.R.; Guerrero-González, T.; Gómez-Conde, E.; Martínez-Fong, D.; González-Barrios, J.A. Characterization of Gene Families Encoding Beta-Lactamases of Gram-Negative Rods Isolated from Ready-to-Eat Vegetables in Mexico City. High-Throughput 2018, 7, 36.

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