Molecular epidemiology of carbapenem-resistant gram-negative bacilli in Ecuador

Abstract Introduction Carbapenem-resistant gram-negative bacilli are a worldwide concern because of high morbidity and mortality rates. Additionally, the increasing prevalence of these bacteria is dangerous. To investigate the extent of antimicrobial resistance and prioritize the utility of novel drugs, we evaluated the molecular characteristics and antimicrobial susceptibility profiles of carbapenem-resistant Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii in Ecuador in 2022. Methods Ninety-five clinical isolates of carbapenem non-susceptible gram-negative bacilli were collected from six hospitals in Ecuador. Carbapenem resistance was confirmed with meropenem disk diffusion assays following Clinical Laboratory Standard Institute guidelines. Carbapenemase production was tested using a modified carbapenemase inactivation method. Antimicrobial susceptibility was tested with a disk diffusion assay, the Vitek 2 System, and gradient diffusion strips. Broth microdilution assays were used to assess colistin susceptibility. All the isolates were screened for the bla KPC, bla NDM, bla OXA-48, bla VIM and bla IMP genes. In addition, A. baumannii isolates were screened for the bla OXA-23, bla OXA-58 and bla OXA-24/40 genes. Results Carbapenemase production was observed in 96.84% of the isolates. The bla KPC, bla NDM and bla OXA-48 genes were detected in Enterobacterales, with bla KPC being predominant. The bla VIM gene was detected in P. aeruginosa, and bla OXA-24/40 predominated in A. baumannii. Most of the isolates showed co-resistance to aminoglycosides, fluoroquinolones, and trimethoprim/sulfamethoxazole. Both ceftazidime/avibactam and meropenem/vaborbactam were active against carbapenem-resistant gram-negative bacilli that produce serin-carbapenemases. Conclusion The epidemiology of carbapenem resistance in Ecuador is dominated by carbapenemase-producing K. pneumoniae harbouring bla KPC. Extensively drug resistant (XDR) P. aeruginosa and A. baumannii were identified, and their identification revealed the urgent need to implement strategies to reduce the dissemination of these strains.