Molecular epidemiology and clinical significance of carbapenemase genes in carbapenem-resistant Acinetobacter baumannii isolates in southern Poland

INTRODUCTION A complex interplay between Acinetobacter spp., patients, and the environment has made it increasingly difficult to optimally treat patients infected with Acinetobacter spp., mainly due to rising antimicrobial resistance and challenges with surveillance. OBJECTIVES This study evaluated carbapenem -resista nt A . baumannii (CRAB) isolates to determine their resistance profiles and the presence of specific 8 -lactamases to inform CRAB surveillance upon hospital admission and regional empiric antibiotic therapies. PATIENTS AND METHODS The study was conducted at 4 hospitals in southern Poland between June and December 2022. Only health care -associated infections caused by A . baumannii were considered. A total of 82 CRAB isolates were included in the analysis. Species identification was performed by matrix -assisted laser desorption/ionization time-of-flight mass spectrometry, antimicrobial susceptibility was determined phenotypically, and polymerase chain reactions were carried out to identify the resistance genes. RESULTS Depending on the hospital, the incidence of CRAB infections varied from 428.6 to 759.5 per 10 000 admissions in intensive care units (ICUs), and from 0.3 to 21 per 10 000 admissions in non -ICUs. CRAB antibiotic susceptibility was the highest for cefiderocol (100%), colistin (96%), tigecycline (77%), gentamicin (51%), and ampicillin / sulbactam (36%). The most prevalent bla OXA genes were bla OXA-66-1 (95%) and bla OX A-40 (71%), and additionally the extended -spectrum 8-lactamase gene bla TEM-1 (41%). CONCLUSIONS An unexpectedly high incidence of CRAB infections occurred in Polish hospitals. There is a need for effective CRAB prevention and control that includes effective hospital screening, national surveillance, and improved treatment options.