Carbapenem-resistant Acinetobacter baumannii: Current status of the problem in four Bulgarian university hospitals (2014-2016)

J Glob Antimicrob Resist. 2019 Mar:16:266-273. doi: 10.1016/j.jgar.2018.10.027. Epub 2018 Nov 6.

Abstract

Objectives: A total of 226 carbapenem-resistant Acinetobacter baumannii (CRAB) isolates was collected during 2014-2016 from inpatients (age range 5-88 years) in four Bulgarian university hospitals (H1-H4) to assess their antimicrobial susceptibility and to explore carbapenem resistance mechanisms as well as the molecular epidemiology of the isolates.

Methods: Antimicrobial susceptibility testing, multiplex PCR, DNA sequencing and electrotransformation experiments were performed. Epidemiological typing by random amplification of polymorphic DNA (RAPD)-PCR was also performed.

Results: The resistance rates were as follows: imipenem, 90.7%; meropenem, 98.2%; doripenem, 100%; amikacin, 92.9%; gentamicin, 87.2%; tobramycin, 55.8%; levofloxacin, 98.2%; trimethoprim/sulfamethoxazole, 86.3%; tigecycline, 22.1%; colistin, 0%; and ampicillin/sulbactam, 41.6%. Intrinsic blaOXA-51-like genes were found in all of the isolates. The majority of the A. baumannii isolates harboured either blaOXA-23-like associated with the upstream-located ISAba1 (26.1%) or blaOXA-40/24-like (46.7%), 45 isolates (19.9%) harboured both genes, and 1 isolate harboured blaOXA-58-like surrounded by ISAba3C upstream and ISAba3 downstream. The blaOXA-58 gene was transferable by electroporation indicating its plasmid location. Epidemiological typing revealed the dissemination of nosocomial CRAB with high clonal relatedness (70% similarity threshold) belonging to six, four, three and two clusters in H1, H2, H3, and H4 hospitals, respectively.

Conclusions: The A. baumannii isolates studied were problematic nosocomial pathogens. Their multidrug resistance greatly limits therapeutic options. The persistence of endemic clones comprised of OXA carbapenemase-producing multidrug-resistant A. baumannii in the monitored hospitals over a period of ca. 3 years is of concern and requires continuous detailed investigations in the future.

Keywords: Acinetobacter baumannii; Carbapenem resistance; Molecular epidemiology; Multidrug resistance; OXA carbapenemases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections / epidemiology*
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / genetics*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology*
  • Bulgaria / epidemiology
  • Carbapenems / pharmacology*
  • Child
  • Child, Preschool
  • Cross Infection / epidemiology
  • Cross Infection / microbiology
  • DNA, Bacterial / genetics
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Hospitals, University / statistics & numerical data*
  • Humans
  • Microbial Sensitivity Tests
  • Middle Aged
  • Young Adult

Substances

  • Anti-Bacterial Agents
  • Carbapenems
  • DNA, Bacterial