Carbapenemase-Encoding Genes and Colistin Resistance in Gram-Negative Bacteria During the COVID-19 Pandemic in Mexico: Results from the Invifar Network.

In this study, we report the carbapenemase-encoding genes and colistin resistance in Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa in the second year of the COVID-19 pandemic. Clinical isolates included carbapenem-resistant K. pneumoniae, carbapenem-resistant E. coli, carbapenem-resistant A. baumannii, and carbapenem-resistant P. aeruginosa. Carbapenemase-encoding genes were detected by PCR. Carbapenem-resistant K. pneumoniae and carbapenem-resistant E. coli isolates were analyzed using the Rapid Polymyxin NP assay. mcr genes were screened by PCR. Pulsed-field gel electrophoresis and whole-genome sequencing were performed on representative isolates. A total of 80 carbapenem-resistant E. coli, 103 carbapenem-resistant K. pneumoniae, 284 carbapenem-resistant A. baumannii, and 129 carbapenem-resistant P. aeruginosa isolates were recovered. All carbapenem-resistant E. coli and carbapenem-resistant K. pneumoniae isolates were included for further analysis. A selection of carbapenem-resistant A. baumannii and carbapenem-resistant P. aeruginosa strains was further analyzed (86 carbapenem-resistant A. baumannii and 82 carbapenem-resistant P. aeruginosa). Among carbapenem-resistant K. pneumoniae and carbapenem-resistant E. coli isolates, the most frequent gene was blaNDM (86/103 [83.5%] and 72/80 [90%], respectively). For carbapenem-resistant A. baumannii, the most frequently detected gene was blaOXA-40 (52/86, 60.5%), and for carbapenem-resistant P. aeruginosa, was blaVIM (19/82, 23.2%). For carbapenem-resistant A. baumannii, five indistinguishable pulsotypes were detected. Circulation of K. pneumoniae New Delhi metallo-ß-lactamase (NDM) and E. coli NDM was detected in Mexico. High virulence sequence types (STs), such as K. pneumoniae ST307, E. coli ST167, P. aeruginosa ST111, and A. baumannii ST2, were detected. Among K. pneumoniae isolates, 18/101 (17.8%) were positive for the Polymyxin NP test (two, 11.0% positive for the mcr-1 gene, and one, 5.6% with disruption of the mgrB gene). All E. coli isolates were negative for the Polymyxin NP test. In conclusion, K. pneumoniae NDM and E. coli NDM were detected in Mexico, with the circulation of highly virulent STs. These results are relevant in clinical practice to guide antibiotic therapies considering the molecular mechanisms of resistance to carbapenems.

Bacterial incidence and drug resistance from pathogens recovered from blood, cerebrospinal and pleural fluids in 2019-2020. Results of the Invifar network.

Background: Antimicrobial resistance is a global concern. Analysis of sterile fluids is essential because microorganisms are defined as significant in most cases. Blood, cerebrospinal, and pleural fluids are frequently received in the microbiology lab because they are associated with considerable rates of morbi-mortality. Knowledge of epidemiology in these samples is needed to choose proper empirical treatments due to the importance of reducing selection pressure. Methods: We used retrospective laboratory data of blood, CSF, and pleural fluid collected from patients in Mexico between 2019 and 2020. Each laboratory identified the strains and tested susceptibility using its routine methods. For Streptococcus pneumoniae, a comparative analysis was performed with data from the broth microdilution method. Results: Forty-five centers participated in the study, with 30,746 clinical isolates from blood, 2,429 from pleural fluid, and 2,275 from CSF. For blood and CSF, Staphylococcus epidermidis was the most frequent. For blood, among gram negatives, the most frequent was Escherichia coli. Among Enterobacterales, 9.8% of K. pneumoniae were carbapenem-resistant. For S. pneumoniae, similar resistance percentages were observed for levofloxacin, cefotaxime, and vancomycin. For CSF, the most frequent gram-negative was E. coli. In Acinetobacter baumannii, carbapenem resistance was 71.4%. The most frequent species detected for pleural fluid was E. coli; in A. baumannii, carbapenem resistance was 96.3%. Conclusion: Gram-negative bacteria, with E. coli most prevalent, are frequently recovered from CSF, blood, and pleural fluid. In S. pneumoniae, the routine, conventional methods showed good agreement in detecting resistance percentages for erythromycin, levofloxacin, and vancomycin.

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 ß-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.