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Background & objectives OXA-232 is a five amino acid substitution variant of OXA-48 and is reported in carbapenem-resistant Klebsiella pneumoniae (CRKP), which is associated with nosocomial infections among immunocompromised patients in the intensive care unit. This study aimed to characterise bla OXA-232 in CRKP of clinical origin and investigate its transcriptional response against sub-inhibitory levels of carbapenems. Methods CRKP was isolated from blood (pathogens) and stool cultures (colonisers) of neonates and was characterized for bla OXA-232 . Co-existing resistance determinants were investigated in bla OXA-232 positive isolates, followed by horizontal gene transferability assay and PCR-based replicon typing (PBRT). Cloning of bla OXA-232 was performed, and expression of bla OXA-232 in the isolates and their clones under sub-inhibitory concentrations of carbapenems was checked via RT-PCR. Mobile genetic elements associated with bla OXA-232 were investigated, followed by DNA fingerprinting through enterobacterial repetitive intergenic consensus (ERIC) PCR. Results bla OXA-232 with co-carriage of extended-spectrum beta-lactamases (ESBLs), sulphonamides and quinolones were identified in seven CRPK isolates recovered from blood samples of neonates. Transformation and cloning of bla OXA-232 was successful. The sub-inhibitory concentration of carbapenems induces elevated expression of this resistant determinant. IS Ecp1 was associated with bla OXA-232 in the upstream region within two haplotypes of CRKP isolates of clinical origin. Interpretation & conclusions Selective carbapenem pressure resulted in higher expression of this gene, which could account for treatment failure. With frequent reports of occurrence among clinical isolates, monitoring and further investigation of this novel variant are necessary to understand its transmission dynamics and to thwart its further dissemination.
Das et al. (Sat,) studied this question.
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