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

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

Automated summary

Successful treatment of Acinetobacter baumannii infections requires early and appropriate antimicrobial therapy, highlighting the importance of understanding the combinations of different beta-lactamase alleles. The study found a variety of bla(OXA) allele combinations in carbapenem-resistant A. baumannii, with bla(OXA-23) being the most commonly found allele.