Nosocomial Outbreak of OXA-48-Producing Klebsiella pneumoniae in a Chinese Hospital: Clonal Transmission of ST147 and ST383

BACKGROUND: In China, the spread and outbreak of OXA-48-producing Enterobacteriaceae remains largely unknown. METHODS: OXA-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 bla(OXA-48) gene. RESULTS: In 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 bla(OXA-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 bla(OXA-48) gene and was truncated by IS1R. CONCLUSIONS: In 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 bla(OXA-48) gene between different K. pneumoniae strains.