Objectives: The objective of this study was to characterize a novel class D carbapenemase, named OXA-372, identified in a carbapenem-resistant Citrobacter freundii strain (Cfr-FI-07) isolated from a hospital wastewater plant in central Italy. Methods: Cfr-FI-07 was isolated using a selective chromogenic medium for carbapenem-resistant Enterobacteriaceae. Carbapenemase production was confirmed by spectrophotometric assay. WGS was carried out using an Illumina MiSeq platform. The functional profile of OXA-372 was investigated by expression of the cloned gene in Escherichia coli and by analysis of kinetic parameters of the purified enzyme. Results: C. freundii Cfr-FI-07 produced carbapenemase activity, but tested negative for common carbapenemase genes. WGS confirmed the absence of known carbapenemase genes and revealed the presence of a novel class D beta-lactamase (DBL) determinant, named blaOXA-372, encoding a protein distantly related to other DBLs. In E. coli, production of OXA-372 conferred resistance to penicillins, including temocillin, and reduced susceptibility to carbapenems, while susceptibility to expanded-spectrum cephalosporins was virtually unaffected. This substrate specificity was confirmed by kinetic characterization of the purified enzyme, which exhibited high catalytic efficiencies for carbapenems (k(cat)/K-M values >= 0.22 s(-1).mu M-1). The bla(OXA-372) gene was associated with a genetic platform of original structure consisting of a Tn402/Tn5053 hybrid transposon derivative, named Tn6255, inserted into a TnPa38-like transposon, named Tn6256, located on an IncA/C-IncN plasmid of approximately 140 kb. Conclusions: OXA-372 is a novel class D carbapenemase, belonging to a new lineage of DBLs, encoded by a gene associated with mobile elements. Functional properties revealed similarities, but also some differences, compared with other class D carbapenemases.
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|Titolo:||OXA-372, a novel carbapenem-hydrolysing class D β-lactamase from a Citrobacter freundii isolated from a hospital wastewater plant|
|Citazione:||Antonelli, A., D'Andrea, M.M., Vaggelli, G., Docquier, J.D., & Rossolini, G.M. (2015). OXA-372, a novel carbapenem-hydrolysing class D β-lactamase from a Citrobacter freundii isolated from a hospital wastewater plant. JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY, 70(10), 2749-2756.|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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