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 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 bla carbapenemase was found in addition to the intrinsic bla allele. The most commonly found allele was bla (n = 78/98). In some isolates, bla was found in addition to other carbapenemase alleles: bla (n = 12/78), bla (n = 2/78) and bla (n = 1/78). Surprisingly, 20% of isolates carried carbapenemases not routinely assayed for by rapid molecular diagnostic platforms, i.e., bla and bla; all had ISAba1 elements. In 8 CR Ab, bla or bla was the only carbapenemase. Both bla and its variant bla were each found in 6/98 isolates. The most prevalent ADC variants were bla (21%), bla (21%), and bla (26%). Complete combinations are reported.