A comprehensive and contemporary "snapshot" of β-lactamases in carbapenem resistant Acinetobacter baumannii

Diagn Microbiol Infect Dis. 2021 Feb;99(2):115242. doi: 10.1016/j.diagmicrobio.2020.115242. Epub 2020 Oct 16.


Successful treatment of Acinetobacter baumannii infections require early and appropriate antimicrobial therapy. One of the first steps in this process is understanding which β-lactamase (bla) alleles are present and in what combinations. Thus, we performed WGS on 98 carbapenem-resistant A. baumannii (CR Ab). In most isolates, an acquired blaOXA carbapenemase was found in addition to the intrinsic blaOXA allele. The most commonly found allele was blaOXA-23 (n = 78/98). In some isolates, blaOXA-23 was found in addition to other carbapenemase alleles: blaOXA-82 (n = 12/78), blaOXA-72 (n = 2/78) and blaOXA-24/40 (n = 1/78). Surprisingly, 20% of isolates carried carbapenemases not routinely assayed for by rapid molecular diagnostic platforms, i.e., blaOXA-82 and blaOXA-172; all had ISAba1 elements. In 8 CR Ab, blaOXA-82 or blaOXA-172 was the only carbapenemase. Both blaOXA-24/40 and its variant blaOXA-72 were each found in 6/98 isolates. The most prevalent ADC variants were blaADC-30 (21%), blaADC-162 (21%), and blaADC-212 (26%). Complete combinations are reported.

Keywords: ADC β-lactamase; Carbapenem resistant Acinetobacter baumannii; OXA carbapenemase; OXA-172; OXA-23; OXA-82.

MeSH terms

  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / enzymology
  • Acinetobacter baumannii / genetics*
  • Acinetobacter baumannii / isolation & purification
  • Bacterial Proteins / genetics*
  • Carbapenems / pharmacology*
  • Genome, Bacterial / genetics
  • Humans
  • beta-Lactam Resistance / genetics*
  • beta-Lactamases / genetics*


  • Bacterial Proteins
  • Carbapenems
  • beta-Lactamases