Dissemination and Characteristics of a Novel Plasmid-Encoded Carbapenem-Hydrolyzing Class D β-Lactamase, OXA-436, Found in Isolates from Four Patients at Six Different Hospitals in Denmark

Abstract

The diversity of OXA-48-like carbapenemases is continually expanding. In this study, we describe the dissemination and characteristics of a novel carbapenem-hydrolyzing class D β-lactamase (CHDL) named OXA-436. In total, six OXA-436-producing isolates, including ( = 3), ( = 2), and ( = 1), were identified in four patients in the period between September 2013 and April 2015. All three species of OXA-436-producing were found in one patient. The amino acid sequence of OXA-436 showed 90.4 to 92.8% identity to the amino acid sequences of other acquired OXA-48-like variants. Expression of OXA-436 in and kinetic analysis of purified OXA-436 revealed an activity profile similar to that of OXA-48 and OXA-181, with activity against penicillins, including temocillin; limited or no activity against extended-spectrum cephalosporins; and activity against carbapenems. The gene was located on a conjugative ∼314-kb IncHI2/IncHI2A plasmid belonging to plasmid multilocus sequence typing sequence type 1 in a region surrounded by chromosomal genes previously identified to be adjacent to genes in spp. In conclusion, OXA-436 is a novel CHDL with functional properties similar to those of OXA-48-like CHDLs. The described geographical spread among different and the plasmid location of illustrate its potential for further dissemination.

Genetic and Biochemical Characterization of OXA-535, a Distantly Related OXA-48-Like β-Lactamase

“…(11,12). The 2,394-bp upstream and 4,074-bp downstream sequences of the bla OXA-535 gene were identical to those of bla OXA-436 , further supporting that the chromosomally encoded bla OXA-535 gene may be the progenitor of the plasmid-encoded bla OXA-436 gene (5). An ISCR1 element found upstream of the bla OXA-436 gene but absent upstream of the bla OXA-535 gene may be responsible for the bla OXA-535-like gene mobilization from the chromosome of Shewanella spp.…”

“…Our findings illustrate the increasing complexity of genetic vehicles at the origin of OXA-48-type carbapenemase spread (7)(8)(9)(10). The finding of ISCR1 upstream of bla OXA-48-like genes is worrisome, because this ISCR1plays an important role in the assembly and transmission of multiple antibiotic resistance genes (5,18,24).…”

Identification of the OXA-48 Carbapenemase Family by Use of Tryptic Peptides and Liquid Chromatography-Tandem Mass Spectrometry

“…As a result, any broadly sensitive OXA-48 assay, including the one described here, will identify enzymes that may not confer carbapenem resistance. Additionally, as noted above, the peptides included in this assay identify at least six OXA family ␤-lactamases not included in the original OXA-48 group, including OXA-436, for which carbapenemase activity has been demonstrated (Table 2) (33,43,44). Another limitation of this assay is that while it provides direct detection of the OXA-48 family proteins, it is unable to detect variants resulting from amino acid substitutions in the peptides selected for the assay.…”

Evaluation of the Revogene Carba C Assay for Detection and Differentiation of Carbapenemase-Producing Gram-Negative Bacteria

“…The chromosomally encoded OXA-535 identified in a Shewanella species (39), which has only 91.3% amino acid identity with OXA-48, has not been detected (data not shown). OXA-535, although not present in Enterobacterales, was used because it is the progenitor of OXA-436, a distantly related OXA-48 variant responsible for an outbreak associated with several enterobacterial species in Denmark (39,40). It is thus likely that OXA-436 would not be detected by the Revogene Carba C assay, and further studies on the Revogene Carba C assay should be carried out to test OXA-436 producers.…”