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 , , , and in the second year of the COVID-19 pandemic. Clinical isolates included carbapenem-resistant , carbapenem-resistant , carbapenem-resistant , and carbapenem-resistant . Carbapenemase-encoding genes were detected by PCR. Carbapenem-resistant and carbapenem-resistant isolates were analyzed using the Rapid Polymyxin NP assay. genes were screened by PCR. Pulsed-field gel electrophoresis and whole-genome sequencing were performed on representative isolates. A total of 80 carbapenem-resistant , 103 carbapenem-resistant , 284 carbapenem-resistant , and 129 carbapenem-resistant isolates were recovered. All carbapenem-resistant and carbapenem-resistant isolates were included for further analysis. A selection of carbapenem-resistant and carbapenem-resistant strains was further analyzed (86 carbapenem-resistant and 82 carbapenem-resistant ). Among carbapenem-resistant and carbapenem-resistant isolates, the most frequent gene was (86/103 [83.5%] and 72/80 [90%], respectively). For carbapenem-resistant , the most frequently detected gene was (52/86, 60.5%), and for carbapenem-resistant , was (19/82, 23.2%). For carbapenem-resistant , five indistinguishable pulsotypes were detected. Circulation of New Delhi metallo-β-lactamase (NDM) and NDM was detected in Mexico. High virulence sequence types (STs), such as ST307, ST167, ST111, and ST2, were detected. Among isolates, 18/101 (17.8%) were positive for the Polymyxin NP test (two, 11.0% positive for the gene, and one, 5.6% with disruption of the gene). All isolates were negative for the Polymyxin NP test. In conclusion, NDM and 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.