Characteristics of the Genetic Spread of Carbapenem-Resistant Acinetobacter baumannii in a Tertiary Greek Hospital

Abstract

Acinetobacter baumannii (Ab) has increasingly been identified as a cause of hospital-acquired infections and epidemics. The rise of carbapenem-resistant Acinetobacter baumannii (CRAB) poses significant challenges in treatment. Nosocomial outbreaks linked to CRAΒ A. baumannii strains have been reported worldwide, including in Greece. This study aimed to analyze the molecular epidemiology trends of multidrug-resistant A. baumannii isolates in a tertiary hospital in Athens, Greece. A total of 43 clinical isolates of extensively drug-resistant (XDRAB), pan-drug-resistant (PDRAB), and CRAB were collected from patients suffering from blood infection, hospitalized between 2016 and 2020 at the internal medicine clinics and the ICU. A.baumannii isolates underwent testing for Ambler class B and D carbapenemases and the detection of ISAba1, and were typed, initially, using pulsed-field gel electrophoresis, and, subsequently, using sequence-based typing and multiplex PCR to determine European Clone lineages. The bla_OXA-23 gene accompanied by ISAba1 was prevalent in nearly all A. baumannii isolates, except for one carrying bla_OXA-58. The intrinsic bla_OXA-51-like gene was found in all isolates. No Ambler class B carbapenemases (VIM, NDM) were detected. Isolates were grouped into four PF-clusters and no one-cluster spread was documented, consistent with the absence of outbreak. The study indicated that XDR/PDR-CRAB isolates predominantly produce OXA-23 carbapenemase and belong to European Clone II. Further research is needed to understand the distribution of resistant bacteria and develop effective prevention and control strategies.

Keywords: Acinetobacter baumannii; Greece; ISAba1; OXA-type carbapenemases; carbapenem resistance; molecular epidemiology.

Figure 1

Annual antibiotic resistance of total BSI A. baumannii isolates. BSIs: bloodstream infections; CRAB = carbapenem-resistant A. baumannii; PDRAB = pan-drug-resistant A. baumannii; XDRAB = extensively drug-resistant A. baumannii.

Figure 2

Dendrogram representing the PFGE pattern of 43 clinical A. baumannii isolates. Four PF-clusters were identified using a cut-off value of ≥80% for the similarity coefficient (vertical line). The isolation date and clinic from which the samples were obtained are shown.