Drug resistance phenotypes and genotypes in Mexico in representative gram-negative species: Results from the infivar network
Authors: Garza-González Elvira , Bocanegra-Ibarias Paola , Bobadilla-del-Valle Miriam , Ponce-de-León-Garduño Luis Alfredo , Esteban-Kenel Verónica , Silva-Sánchez Jesus , Garza-Ramos Ulises , Barrios-Camacho Humberto , López-Jácome Luis Esaú , Colin-Castro Claudia A. , Franco-Cendejas Rafael , Flores-Treviño Samantha , Morfín-Otero Rayo , Rojas-Larios Fabian , Mena-Ramírez Juan Pablo , Fong-Camargo María Guadalupe , Morales-De-la-Peña Cecilia Teresita , García-Mendoza Lourdes , Choy-Chang Elena Victoria , Aviles-Benitez Laura Karina , Feliciano-Guzmán José Manuel , López-Gutiérrez Eduardo , Gil-Veloz Mariana , Barajas-Magallón Juan Manuel , Aguirre-Burciaga Efren , López-Moreno Laura Isabel , Martínez-Villarreal Rebeca Thelma , Canizales-Oviedo Jorge Luis , Cetina-Umaña Carlos Miguel , Romero-Romero Daniel , Bello-Pazos Fidencio David , Barlandas-Rendón Nicolás Rogelio Eric , Maldonado-Anicacio Joyarib Yanelli , Bolado-Martínez Enrique , Galindo-Méndez Mario , Perez-Vicelis Talia , Alavez-Ramírez Norma , Méndez-Sotelo Braulio J. , Cabriales-Zavala Juan Francisco , Nava-Pacheco Yirla Citlali , Moreno-Méndez Martha Irene , García-Romo Ricardo , Silva-Gamiño Aldo Rafael , Avalos-Aguilera Ana María , Santiago-Calderón María Asunción , López-García Maribel , Velázquez-Acosta María del Consuelo , Cobos-Canul Dulce Isabel , Vázquez-Larios María del Rosario , Ortiz-Porcayo Ana Elizabeth , Guerrero-Núñez Arely Elizabeth , Valero-Guzmán Jazmín , Rosales-García Alina Aracely , Ostos-Cantú Heidy Leticia , Camacho-Ortiz Adrián 
Published: March 2021

Aim
This report presents phenotypic and genetic data on the prevalence and characteristics of extended-spectrum β-lactamases (ESBLs) and representative carbapenemases-producing Gram-negative species in Mexico.

Material and methods
A total of 52 centers participated, 43 hospital-based laboratories and 9 external laboratories. The distribution of antimicrobial resistance data for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, Acinetobacter baumannii complex, and Pseudomonas aeruginosa in selected clinical specimens from January 1 to March 31, 2020 was analyzed using the WHONET 5.6 platform. The following clinical isolates recovered from selected specimens were included: carbapenem-resistant Enterobacteriaceae, ESBL or carbapenem-resistant E. coli, and K. pneumoniae, carbapenem-resistant A. baumannii complex, and P. aeruginosa. Strains were genotyped to detect ESBL and/or carbapenemase-encoding genes.

Results
Among blood isolates, A. baumannii complex showed more than 68% resistance for all antibiotics tested, and among Enterobacteria, E. cloacae complex showed higher resistance to carbapenems. A. baumannii complex showed a higher resistance pattern for respiratory specimens, with only amikacin having a resistance lower than 70%. Among K. pneumoniae isolates, blaTEM, blaSHV, and blaCTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, blaTEM, blaSHV, and blaCTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was blaCTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was blaNDM-1 (81.5%), followed by blaOXA-232 (14.8%) and blaoxa-181(7.4%), in A. baumannii was blaOXA-24 (76%) and in P. aeruginosa, was blaIMP (25.3%), followed by blaGES and blaVIM (13.1% each).

Conclusion
Our study reports that NDM-1 is the most frequent carbapenemase-encoding gene in Mexico in Enterobacteriaceae with the circulation of the oxacillinase genes 181 and 232. KPC, in contrast to other countries in Latin America and the USA, is a rare occurrence. Additionally, a high circulation of ESBL blaCTX-M-15 exists in both E. coli and K. pneumoniae.