Population structure of OXA-48-producing Klebsiella pneumoniae ST405 isolates during a hospital outbreak characterised by genomic typing

Abstract

Objectives: The aim of this study was to investigate the structure of a broad and sustained hospital outbreak of OXA-48-producing Klebsiella pneumoniae (KpO48) belonging to sequence type 405 (ST405). Methods: Whole-genome sequencing and comparison of ten ST405 KpO48 isolates obtained from clinical samples in our hospital was performed. Using stringent criteria, 36 single nucleotide polymorphisms (SNPs) were detected (range 0–21 in pairwise comparisons), and allele-specific PCR was used to call the SNPs among a larger set of isolates. Results: Several haplotypes were identified within the population. The haplotypes did not show a spatial structure, but a temporal evolution of sequential haplotype replacements was observed. Conclusions: The dispersed spatial distribution suggests a reservoir formed by a large pool of colonised patients, and the temporal replacement pattern suggests that the sustained outbreak was composed of several small outbreaks that appeared and rapidly dispersed to several units.