Identification of CTX-M15-, SHV-28-producing Klebsiella pneumoniae ST15 as an epidemic clone in the Copenhagen area using a semi-automated Rep-PCR typing assay

Abstract

Rapid molecular typing methods can be a valuable aid in the investigation of suspected outbreaks. We used a semi-automated repetitive sequence-based polymerase chain reaction (Rep-PCR) typing assay and pulsed field gel electrophoresis (PFGE) to investigate the relationship between local Klebsiella pneumoniae (K. pneumoniae) producing extended spectrum β-lactamases (ESBLs) and their relation to recognized Danish outbreak strains. PFGE and Rep-PCR produced similar clustering among isolates. Individual isolates from each cluster were further characterized by PCR amplification and sequencing of bla (TEM), bla (SHV), and bla (CTX-M), and multilocus sequence typing (MLST). Thirty-five out of 52 ESBL-producing K. pneumoniae isolates were ST15 and bla (CTX-M15), bla (SHV-28), and bla (TEM-1) positive by PCR. Ten out of 52 were ST16 and tested positive for bla (CTX-M15), bla (SHV-1), and bla (TEM-1). Isolates from previously recognized hospital outbreaks were also ST15 and PCR positive for bla (CTX-M15), bla (SHV-28), and bla (TEM-1), and typed within the main cluster by both Rep-PCR and PFGE. In conclusion, K. pneumoniae ST15 containing bla (CTX-M15) and bla (SHV-28) constitutes an epidemic clone in the Copenhagen area and this clone can be rapidly recognized by semi-automated Rep-PCR.