Epidemiological and genomic characterization of carbapenem-resistant Acinetobacter baumannii ST600 harbouring the blaNDM-1 gene, first report in Poland.

Abstract

Background: Acinetobacter baumannii (Ab) causes severe infections among intensive care units (ICU) and mechanically ventilated patients. According to the European Centre for Disease Prevention and Control data for 2018 the prevalence of Ab in Polish ICUs was higher than in other European countries, while almost 40% of Ab were resistant to carbapenems (CR-Ab) in 2021. Our goal was to investigate the epidemiology and molecular characteristics of CR-Ab strains collected from the University Hospital in Krakow, Poland, by whole-genome sequencing (WGS) and phenotypic tests.

Methods: Epidemiological and drug-resistance data from a total of 667 hospital-acquired (HAI) CR-Ab infections collected in 2019 (442) and 2021 (235) were examined. Bacterial identification, antimicrobial susceptibility and detection of carbapenemases were performed. A selected subset of 125 CR-Ab isolated in 2021 was investigated by WGS.

Results: Among 125 CR-Ab isolates examined by WGS, the vast majority 104 (82%), belonged to the most prevalent ST2, and whereas 20 (16%) belonged to the rarely reported ST600. The most common genes conferring resistance to carbapenems were bla_OXA-66 (96.8%), and bla_OXA-72 (71.2%), whereas bla_OXA-23 and bla_NDM-1 genes were specific to ST600 isolates. The bla_NDM-1 gene was chromosomally located in IS30 of Tn125.

Conclusions: Our study reveals the presence of CR-Ab of the sporadically reported ST600 harbouring the bla_NDM-1 gene, reported for the first time in Poland. Routine genomic surveillance should be implemented to monitor and reduce the transmission of circulating resistant Ab clones.