Carbapenem-Hydrolyzing Oxacillinase, OXA-48, Persists in Klebsiella pneumoniae in Istanbul, Turkey

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Abstract
Two OXA-48-producing Klebsiella pneumoniae isolates (KP-4936 and KP-154488) were analyzed. Minimum inhibitory concentrations were determined using agar dilution and E-test, beta-lactamase production by phenotypic tests (E-test MBL and ESBL, isoelectric focusing, and bioassay) and molecular methods (PCR, RAPD-PCR, sequencing, plasmid analysis, and conjugation). Isolates were resistant to all beta-lactams, including carbapenems. PCR and sequencing identified bla(OXA-48) in both isolates and the transconjugant. KP-4936 harbored bla(TEM-1) (pI 5.4) and bla(CTX-M-15) genes (pI 8.6), while KP-154488 was positive for bla(TEM-1) (pI 5.4), bla(CTX-M-15) (pI 8.9), and bla(SHV2a) (pI 7.6), in addition. The enzyme with a pI of 7.2 hydrolyzed imipenem according to a bioassay result. Plasmids (70 and 140 kb) from KP-4936 were transferred by conjugation. RAPD-PCR found no clonal relationship between the two strains. Carbapenem resistance may spread among Enterobacteriaceae via the transferable enzyme OXA-48.