Molecular characterization of Danish ESBL/AmpC-producing Klebsiella pneumoniae from bloodstream infections, 2018.

Abstract Objectives The aim was to molecular characterise 3rd generation cephalosporin resistant Klebsiella pneumoniae isolated from bloodstream infections in Denmark in 2018 using WGS data, and to compare these isolates to the most common clones detected in 2006 and 2008. Methods Sixty-two ESBL/AmpC-producing K. pneumoniae isolates from Danish blood cultures from 2018 were analysed using whole-genome sequencing to obtain MLST, cgMLST, resistance profile, and phylogeny. These were compared to the most common ESBL K. pneumoniae clones detected in 2006 and 2008. Results The most common ESBL-clone was ST15 CTX-M-15, the DHA-1 gene the most common in AmpC isolates and the OXA-48-like group the most common carbapenemase. Thirty-nine different STs were found with the most frequent being ST14, ST15 and ST37, accounting for 24% of the isolates. The isolates were subdivided into 55 cluster types (CTs) of which 49 were singletons and the most frequent being ST14-CT2080. Two of the CTX-M-15- producing isolates from 2018 belonged to the ST15-CT105/CT3078 clone, which was first detected in 2006. Conclusions The ESBL/AmpC/CPO K. pneumoniae isolates detected in Danish blood cultures belonged to many different types. No dominant clones were circulating in the Danish hospitals, but the ST15-CT105/CT3078 CTX-M-15 K. pneumoniae clone, was seen 13 years after its first detection.