Contribution of a Plasmid-Borne bla _OXA-58 Gene with Its Hybrid Promoter Provided by IS 1006 and an IS Aba3 -Like Element to β-Lactam Resistance in Acinetobacter Genomic Species 13TU

Abstract

The contribution of the bla OXA-58 gene and its promoter to ␤-lactam resistance has not been validated in Acinetobacter spp. other than Acinetobacter baumannii. We identified a multidrug-resistant (including carbapenem resistance) Acinetobacter genomic species 13TU in which bla OXA-58 was the only detected carbapenemase gene. The bla OXA-58 gene was plasmid located, flanked by ISAba3 (downstream) and an ISAba3-like element (upstream). An IS1006 element was inserted into ISAba3-like (IS1006-⌬ISAba3-like) to generate a hybrid promoter for bla OXA-58 , with a ؊35 promoter located in IS1006 and a ؊10 promoter in ISAba3-like. The reference strain of Acinetobacter genomic species 13TU, ATCC 17903, revealed higher MICs of amoxicillin, ticarcillin, and piperacillin and heteroresistance to imipenem and meropenem when it was transformed with a shuttle vector containing a fragment encompassing ⌬ISAba3-like-bla OXA-58 , compared to the same host containing only bla OXA-58 . When the fragment was changed from ⌬ISAba3-like-bla OXA-58 to IS1006-⌬ISAba3-like-bla OXA-58 , the ATCC 17903 transformant revealed a markedly higher level of bla OXA-58 transcription (12-fold), increased cefuroxime and piperacillin-tazobactam MICs, and homoresistance to imipenem and meropenem. Different roles of the insertion elements preceding the bla OXA-58 gene in Acinetobacter genomic species 13TU are demonstrated. The ISAba3-like--bla OXA-58 construct can mediate resistance to penicillin derivatives but only heteroresistance to carbapenems. The insertion of IS1006 into ISAba3-like, generating a hybrid promoter, could further enhance the transcription of bla OXA-58 and mediate homoresistance to carbapenems and also enhanced resistance to piperacillin-tazobactam.

First isolation of Acinetobacter johnsonii co-producing PER-2 and OXA-58 β-lactamases

“…These strains harbored neither bla OXA-23 nor bla OXA-58 . On the other hand, in the isolate 2199, we observed the presence of imipenem-resistant subpopulations in accordance with a previous report by Chen et al (2010) who demonstrated that ISAba3-like bla OXA-58 could mediate resistance to penicillin derivatives but only heteroresistance to carbapenems.…”

Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture

“…S1 in the supplemental material). The generation of electrocompetent cells and electrotransformation were performed as previously described (20). Restriction enzymes were purchased from New England BioLabs (Beverly, MA, USA).…”

Sheltering Effect and Indirect Pathogenesis of Carbapenem-Resistant Acinetobacter baumannii in Polymicrobial Infection

“…Bacteria belonging to the family Enterobacteriaceae and Pseudomonas aeruginosa were identified using a Vitek II system (bioMéri-eux, Marcy l'Etoile, France). Genes encoding class A, B, and D carbapenemases and the upstream insertion sequence of CHDL genes were detected by a PCR method, as previously described (19,20). Phenotypic tests were used to identify class B metallo-␤-lactamases, as previously described (20).…”