Carbapenem resistance in major Gram-negative pathogens Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa in an oncological hospital: frequency, distribution, and resistance profiles

Objective. To assess the frequency and resistance profiles to meropenem and imipenem among key Gram-negative pathogens A. baumannii, K. pneumoniae, E. coli, and P. aeruginosa in an oncological hospital setting. Material and methods. A retrospective multicenter cohort study was conducted at three clinical branches of the National Medical Research Radiological Centre (Moscow, Obninsk) from January 2023 to May 2024. A total of 1445 unique isolates from 1445 patients with nosocomial infections caused by K. pneumoniae, P. aeruginosa, A. baumannii, and E. coli were analyzed. The susceptibility to meropenem and imipenem was studied in carbapenem-resistant clinical isolates. Results. Resistance to meropenem/imipenem was: A. baumannii 60.0/56.5%, P. aeruginosa 37.4/55.5%, K. pneumoniae 37.9/42.2%, and E. coli 4.2% (meropenem only). Cross-resistance did not exceed 41.9%. Non-fermenting bacteria predominated in intensive care units, while Enterobacteriaceae predominated in urology departments. Conclusion. A high level of carbapenem resistance among major Gram-negative pathogens was established. Incomplete cross-resistance supports the possibility of within-class antibiotic substitution. Local epidemiology should be taken into account when choosing empirical therapy.