High-level carbapenem-resistant OXA-48-producing Klebsiella pneumoniae with a novel OmpK36 variant and low-level, carbapenem-resistant, non-porin-deficient, OXA-181-producing Escherichia coli from Thailand

Five bla(OXA-48-like)-carrying Enterobacteriaceae isolates collected from two Thai patients in December 2012 were characterized. Three Klebsiella pneumoniae isolates giving two different pulsed-field gel electrophoresis patterns and sequence types (ST11 and ST37) from patient 1 harbored bla(OXA-48) locating on Tn1999.2, whereas two Escherichia coli isolates with the same pulsotype and ST5 from Patient 2 carried ISEcp1-associated One K. pneumoniae strain had bla(SHV-12), bla(DHA-1), qnrB, and qnrS, while another strain harbored bla(CTX-M-15), qnrS and aac(6')-Ib-cr. The E. coli strain contained bla(CTX-M-15), bla(CMY-2), qnrS, and aac(6')-Ib-cr. Interestingly, the OXA-48 producers with a novel OmpK36 variant by a substitution of Gly to Asp in the L3 loop-borne PEFXG motif exhibited high-level resistance to ertapenem, imipenem, and meropenem. In contrast, the OXA-181 producer with non-porin-deficient background showed low-level resistance to ertapenem only. Both patients died because of either septic shock or pneumonia. This study showed the impact of OXA-48-like carbapenemases in porin-defective clinical isolate background, which may lead to serious therapeutic problems in the near future. (C) 2016 Elsevier Inc. All rights reserved.