Characterization of the novel OXA-213-like β-lactamase OXA-822 from Acinetobacter calcoaceticus

Abstract

Objectives This study analysed the novel carbapenem-hydrolysing class D β-lactamase OXA-822 identified in the clinical Acinetobacter calcoaceticus isolate AC_2117. Methods WGS was employed for identification of β-lactamases. Micro-broth dilution was used for evaluation of antibiotic susceptibility of AC_2117 and transformants containing blaOXA-822. After heterologous purification of OXA-822, OXA-359 and OXA-213, enzyme kinetics were determined using spectrometry. The effect of OXA-822 upon meropenem treatment was analysed in the Galleria mellonella in vivo infection model. Results OXA-822 is a member of the intrinsic OXA-213-like family found in A. calcoaceticus and Acinetobacter pittii. Amino acid sequence similarity to the nearest related OXA-359 was 97%. Production of OXA-822, OXA-359 and OXA-213 in Acinetobacter baumannii ATCC® 19606T resulted in elevated MICs for carbapenems (up to 16-fold). Penicillinase activity of the purified OXA-822 revealed high KM values, in the millimolar range, combined with high turnover numbers. OXA-822 showed the highest affinity to carbapenems, but affinity to imipenem was ∼10-fold lower compared with other carbapenems. Molecular modelling revealed that imipenem does not interact with a negatively charged side chain of OXA-822, as doripenem does, leading to the lower affinity. Presence of OXA-822 decreased survival of infected Galleria mellonella larvae after treatment with meropenem. Only 52.7% ± 7.7% of the larvae survived after 24 h compared with 90.9% ± 3.7% survival in the control group. Conclusions The novel OXA-822 from a clinical A. calcoaceticus isolate displayed penicillinase and carbapenemase activity in vitro, elevated MICs in different species and decreased carbapenem susceptibility in A. baumannii in vivo.

Phenotypic and Genotypic Characteristics of a Tigecycline-Resistant Acinetobacter pittii Isolate Carrying blaNDM–1 and the Novel blaOXA Allelic Variant blaOXA–1045

“…Noteworthy, the MICs of ceftazidime, cefotaxime, meropenem, and imipenem for both transformants remained the same as the acceptor strain, demonstrating that the OXA-213 resistance profile to cephalosporins and carbapenem was similar to that of OXA-1045 ( Table 4 ). A previous study has illustrated that the production of all OXAs led to a significant increase in all carbapenem MICs in A. baumannii , while no elevation in MICs was observed in E. coli ( Tietgen et al, 2021 ). Indeed, we could not rule out the possibility that the effect on MICs is a result of endogenous OXA cooperation with vector-expressed OXA-213-like variants in Acinetobacter spp.…”

“…Among these carbapenem-hydrolyzing OXA-type lactamases, bla OXA–23 is regarded as an intrinsic gene of Acinetobacter radioresistens , OXA-51 is intrinsic to A. baumannii and the OXA-134 variant is intrinsic to Acinetobacter schindleri and A. lwoffii ( Poirel et al, 2008 ; Turton et al, 2012 ; Périchon et al, 2014 ). OXA-213-like enzymes have been identified to be intrinsic to A. calcoaceticus and have been subsequently detected in A. pittii ( Figueiredo et al, 2012 ; Tietgen et al, 2021 ). Phylogenetic analysis of OXA-213-like proteins identified two distinct subgroups within the OXA family.…”

“…to carbapenem antibiotics is based on the production of the carbapenem-hydrolyzing class D β-lactamases (CHDLs), such as bla OXA–23–like ( Singkham-In and Chatsuwan, 2018 ), bla OXA–24–like ( Ji et al, 2014 ), bla OXA–58–like ( Ji et al, 2014 ), bla OXA–72–like ( Montealegre et al, 2012 ), and other variants. They can be intrinsic and have a limited ability to hydrolyze carbapenems, but can also result in a resistant phenotype, particularly when overproduced ( Tietgen et al, 2021 ). There are three characterized resistance-nodulation-cell division (RND) efflux pumps: AdeABC, AdeFGH, and AdeIJK.…”

Galleria mellonella as a Good Model to Study Acinetobacter baumannii Pathogenesis

“…The extreme adaptability of A. baumannii to antibiotics has allowed this microorganism to develop various resistance mechanisms, and has contributed to the emergence of MDR and even pan-resistant strains worldwide. G. mellonella has been established and accepted as one of the in vivo models to explore the A. baumannii drug-resistance mechanisms involved in β-lactamases [81], aminoglycoside modifying enzymes [59], and antibiotic target modifications [60].…”

“…Class D β-lactamases (also named oxacillinases (OXAs)) usually hydrolyze carbapenem antibiotics such as isoxazolylpenicillin, oxacillin, and benzylpenicillin, which are commonly used against A. baumannii [115]. Tietgen et al found a novel β-lactamase, OXA-822, isolated from Acinetobacter calcoaceticus [81]. The production of OXA-822 was done in A. baumannii, and tested upon meropenem treatment in G. mellonella infection assays.…”