Klebsiella pneumoniae ST307 with OXA-181: Threat of a high-risk clone and promiscuous plasmid in a resource-constrained healthcare setting

Introduction: Klebsiella pneumoniae with OXA-48-like enzymes were introduced into Tshwane Tertiary Hospital (TTH) (Pretoria, South Africa) during September 2015, causing nosocomial outbreaks. Methods: PCR methodologies and WGS were used to characterize K. pneumoniae with carbapenemases (n = 124) from TTH (July 2015-December 2016). Results: PCR was used to track K. pneumoniae ST307 with OXA-181 among 60% of carbapenemase-positive isolates in different wards/units over time and showed the transmission of IncX3 plasmids to other K. pneumoniae clones. WGS identified different ST307 clades: 307-OXA181 (consisting of two lineages, A and B) with OXA-181 on IncX3 plasmids (named p72-X3-OXA181) and clade 307-VIM with VIM-1 on IncFII plasmids. Clade 307-OXA181 lineage B was responsible for the rapid increase and transmission of OXA-181 K. pneumoniae in various wards/units throughout TTH, while the numbers of clade 307-OXA181 lineage A and clade 307-VIM remained low. Separate outbreaks were due to K. pneumoniae ST17 and ST29 with p72-X3-OXA181 plasmids. Conclusions: The high-risk clone K. pneumoniae ST307 with OXA-181 rapidly spread to different wards/units despite infection and prevention measures. ST307 clades and lineages seemingly acted differently in outbreak situations. This study also highlighted the threat of promiscuous plasmids such as p72-X3-OXA181.