The Evolution of Antimicrobial Resistance in Mexico During the Last Decade: Results from the INVIFAR Group

Background: Surveillance of antimicrobial resistance (AMR) requires an international approach with national and local strategies. Our aim was to summarize a retrospective 10-year report of antibiotic resistance of gram-positive and gram-negative bacteria in Mexico. Methods: A total of 46 centers from 22 states of Mexico participated. Databases of AMR from January 2009 to December 2018 were included for most species. The 10-year period was divided into five 2-year periods. Results: For Staphylococcus aureus, a decrease in resistance in all specimens was observed for erythromycin and oxacillin (p < 0.0001 for each). For Enterobacter spp., resistance to meropenem increased for urine specimens (p = 0.0042). For Klebsiella spp., increased drug resistance in specimens collected from blood was observed for trimethoprim/sulfamethoxazole, gentamicin, tobramycin (p < 0.0001 for each), meropenem (p = 0.0014), and aztreonam (p = 0.0030). For Acinetobacter baumannii complex, high drug resistance was detected for almost all antibiotics, including carbapenems, except for tobramycin, which showed decreased resistance for urine, respiratory, and blood isolates (p < 0.0001 for each), and for amikacin, which showed a decrease in resistance in urine specimens (p = 0.0002). An increase in resistance to cefepime was found for urine, respiratory, and blood specimens (p < 0.0001 for each). For Pseudomonas aeruginosa, aztreonam resistance increased for isolates recovered from blood (p = 0.0001). Conclusion: This laboratory-based surveillance of antibiotic resistance shows that resistance is increasing for some antibiotics in different bacterial species in Mexico and highlights the need for continuous monitoring of antibiotic resistance.

Drug resistance phenotypes and genotypes in Mexico in representative gram-negative species: Results from the infivar network

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, bla_TEM, bla_SHV, and bla_CTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, bla_TEM, bla_SHV, and bla_CTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was bla_CTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was bla_NDM-1 (81.5%), followed by bla_OXA-232 (14.8%) and bla_oxa-181(7.4%), in A. baumannii was bla_OXA-24 (76%) and in P. aeruginosa, was bla_IMP (25.3%), followed by bla_GES and bla_VIM (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 bla_CTX-M-15 exists in both E. coli and K. pneumoniae.