OXA-48 carbapenemase-producing Klebsiella pneumoniae isolated from Libyan patients.

Abstract

Six multidrug-resistant Klebsiella pneumoniae isolates were recovered from injured Libyan combatants. Production of carbapenemase was screened by using commercial combination tablets from Rosco combined with a temocillin disk. Polymerase chain reaction (PCR) and sequencing were used to detect several carbapenemase genes and to characterize their genetic environment. Genetic support was studied by mating-out assays. Plasmid size was identified by the KADO method. PCR and sequencing allowed characterization of plasmid scaffold. Genotyping was performed by pulse-field gel electrophoresis (PFGE) and multilocus sequence typing. PCR was used to check for the presence of nine genes linked to virulence in K. pneumoniae. No carbapenemase was identified by Rosco disks, but all isolates showed high-level temocillin resistance. All of them harbored blaOXA-48 in the transposon Tn1999.2, on a self-conjugative plasmid of about 60 kb, similar to pOXA-48. PFGE revealed three clusters in which isolates were genetically related: The first comprised FM9 and FM10, and the second comprised FM1, FM4, and FM5. FM2 formed a third distinct clone. Sequence types ST101, ST11, and ST147 were identified in keeping with PFGE results. The entB, ycfM, ybtS, and mrkD genes were detected in all isolates, and kfu gene was present in the three ST101 strains. This work confirms the current and successful spread of blaOXA-48 by horizontal dissemination of a single IncL/M plasmid through different genetic backbones with strong epidemic potential. It also highlights the need for rapid and reliable phenotypic detection methods. Attempts to link virulence factors and the production of this carbapenemase deserve further studies.