Abstract
BackgroundIn China, the spread and outbreak of OXA-48-producing Enterobacteriaceae remains largely unknown.MethodsOXA-48-producing isolates were analyzed for genetic relatedness by pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility by E-test, and sequence type (ST) by multilocus sequence typing. S1-PFGE and southern blotting were used for plasmid profiling, and PCR and subsequent sequencing were performed to determine the genetic environment of blaOXA-48 gene.ResultsIn total, 37 non-duplicated OXA-48-producing K. pneumoniae (OXAKp) isolates were recovered. From December 2013 to August 2014, an outbreak was observed at a respiratory ICU. The 37 isolates of K. pneumoniae were categorized into four PFGE types (A, B, C, and D). The predominant strains associated with the outbreak were strains with PFGE type A and B, which belonged to ST383 and ST147, respectively. Plasmid sequencing revealed that the blaOXA-48-carrying plasmid is 69,069 bp in length and belongs to the IncL/M incompatibility group. Sequence analysis revealed that the IS1999 element was located upstream of the blaOXA-48 gene and was truncated by IS1R.ConclusionsIn this study, the dissemination and outbreak of OXAKp isolates were clonal, and ST147 and ST383 K. pneumoniae were the predominant clones that were associated with the outbreak. Meanwhile, the horizontal transfer of plasmids potentially mediate the spread of blaOXA-48 gene between different K. pneumoniae strains.
Highlights
Global spread of carbapenemase-producing Klebsiella pneumoniae is a growing clinical problem and public health threat [1]
The 37 isolates of K. pneumoniae were categorized into four pulsed-field gel electrophoresis (PFGE) types (A, B, C, and D)
The predominant strains associated with the outbreak were strains with PFGE type A and B, which belonged to ST383 and ST147, respectively
Summary
Global spread of carbapenemase-producing Klebsiella pneumoniae is a growing clinical problem and public health threat [1]. OXA-48-producing K. pneumoniae (OXAKp) has been primarily reported in Turkey, and in countries of the Middle East, North Africa, and Europe [1,3]. OXA-48 and its several variants have been identified in Enterobacteriaceae [6,7]. These variants differ from OXA-48 by one to five amino acid substitutions [6]. OXA-48-type carbapenemases weakly hydrolyze carbapenems, but does not exhibit activity against extended-spectrum cephalosporins and aztreonam. A recent study demonstrated that the OXA48-like variants possessed different carbapenems hydrolytic properties, while OXA-163 variant did not exhibit significant carbapenemase activity [8]. In China, the spread and outbreak of OXA-48-producing Enterobacteriaceae remains largely unknown
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