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 IS 1999 element was located upstream of the bla OXA-48 gene and was truncated by IS 1R . 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.