OXA-253, a Variant of the Carbapenem-Hydrolyzing Class D β - Lactamase OXA-143 in Acinetobacter baumannii

Abstract

The carbapenem-hydrolyzing class D ␤-lactamase OXA-253 was identified in an Acinetobacter baumannii clinical isolate belonging to sequence type 113 (ST113) in Brazil. OXA-253 shares 93.8% amino acid identity with OXA-143. The bla OXA-253 gene is located on a ca. 20-kb plasmid. The genetic environment of the bla OXA-253 gene shares the highest identity with ubiquitous GR2 group plasmids usually carrying bla OXA-24/-40 genes.A cinetobacter baumannii strains are frequently associated with nosocomial infections, and their resistance to carbapenems has risen in recent decades (1, 2). The main mechanisms of resistance to carbapenems of A. baumannii are efflux pumps, porin mutations, overexpression of the chromosomally encoded OXA-51-like ␤-lactamase, and the biosynthesis of acquired carbapenem-hydrolyzing class D ␤-lactamases (CHDLs) (oxacillinases) (3). To date, five main groups of CHDLs have been identified in A. baumannii, the intrinsic chromosomally encoded OXA-51-like enzyme and the acquired chromosomally encoded and plasmidencoded OXA-23-like, OXA-40-like, OXA-58-like, and OXA-143-like enzymes (3). OXA-143 was first described in 2009 from an A. baumannii strain isolated in Brazil in 2004 (2). In this study, we report an A. baumannii clinical strain producing OXA-253, a variant of OXA-143. The genetic environment of the plasmidborne bla OXA-253 gene is detailed.The clinical isolate A. baumannii 25 was recovered from a perineal swab in the intensive care unit in Minas Gerais Hospital, Brazil. MICs were determined by Etest (bioMérieux, La Balmeles-Grottes, France). Isolate 25 was resistant to all ␤-lactams, including carbapenems, and had reduced susceptibility to cefepime according to the CLSI guidelines (4) ( Table 1). It was also resistant to fluoroquinolones (ciprofloxacin), and susceptible to aminoglycosides (gentamicin, tobramycin, amikacin, and netilmicin), and tetracycline. A modified version of the CarbaNP test (5) and the CarbAcinetoNP test (P. Nordmann, personal communication) was performed and showed a carbapenemase activity. PCR experiments, performed as previously described for screening of bla , bla , bla OXA-58 and bla OXA-143 genes (6), identified a bla OXA-143 -like gene. Further sequencing of the PCR product identified the bla OXA-253 gene (GenBank number KC479324) and showed 95% nucleotide identity with the bla OXA-143 gene. The deduced protein sequence showed 17 amino acid differences between OXA-143 and OXA-253 (93.8% identity) (Fig. 1). Those amino acid changes do not occur in the conserved residues STFK (position 70 to 73) and KSG (position 216 to 218) of class D ␤-lactamases or in the FGN structural element (position 144 to 146) of carbapenem-hydrolyzing class D ␤-lactamases (CHDLs) (Fig. 1).Plasmid extraction from A. baumannii 25 performed by the Kieser technique yielded two plasmids of ca. 70 and 20 kb (7). The gene encoding the OXA-253 determinant from A. baumannii 25 was transferred to Escherichia coli TOP10 by electroporation. The resulting E. coli TOP10 strain harboring the plasmid o...

Acquired Class D β-Lactamases

“…OXA-231 is a single amino acid derivative of OXA-143 that was recently isolated in Brazil. No data regarding the contribution of the enzyme to β-lactam susceptibility are available [ 127 ].…”

“…The genes encoding OXA24/40-like enzymes are found both on the chromosome [ 114 ] and on plasmids [ 120 , 122 ] and do not appear associated with insertion sequences or integrons. There is a suggestion that they may be acquired through homologous recombination since they are bracketed by two copies of the same replicase gene [ 126 , 127 ].…”

High Frequency of OXA-253-Producing Acinetobacter baumannii in Different Hospitals in Recife, Brazil

“…Manual inspection of smaller contigs and reads matching to the plasmid pABVA01 also led to the identification, for most strains, of overlapping contigs covering nearly all of the plasmid and compatible with circular DNA elements 9 to 10 kb in length. The genetic environment surrounding the bla OXA-253 gene was also investigated and, in general, the genetic organization seen was similar to what was found in A. baumannii isolates producing OXA-253 and OXA-24 in Brazil and Italy, respectively (9,10). In almost all isolates, the bla OXA-253 gene was found to be flanked by conserved elements, including genes coding for hypothetical proteins, a membrane protein, and a TonB-dependent receptor gene.…”

“…A detailed report of the whole-genomic data analysis, in the context of resistance and virulence characteristics, will be provided in future publications. Analysis of the sequencing data led to identification in 31 strains of the recently described class D ␤-lactamase bla OXA-253 (9). According to a multilocus sequence typing (MLST) analysis based on the sequenced genes, these strains were assigned to five different STs (ST 1, ST 15, ST 25, ST 79, and ST 113).…”

Caracterização genética e perfil de sensibilidade antimicrobiana de cepas multirresistentes de Acinetobacter baumannii presentes em um hospital de ensino

“…Unidos, Argentina e Bolívia (Peleg, Seifert e Paterson, 2008;Poirel et al, 2005;Sevillano et al, 2012;Wu et al, 2015). (Camargo et al, 2016;Gionco et al, 2012), Rio de Janeiro (Werneck et al, 2011b) (Carvalho et al, 2015;de Sá Cavalcanti et al, 2016;de Sá Cavalcanti et al, 2013;Girlich et al, 2014;Martins e Barth, 2013;Pagano et al, 2017) …”