1. Promiscuous plasmids? Scaling infection control implications of horizontal spread of carbapenemase genes between species
Siddharth Mookerjee, Frances Davies, Eleonora Dyakova, Tracey Galletly, Alison Holmes, Jonathan Otter
Imperial College Healthcare NHS Trust & Imperial College London
 @jonotter
Introduction
Carbapenemase-producing Enterobacteriaceae (CPE) are of urgent public health concern, with a steady increase in incidence year on year in the UK.1
It is currently unclear how much importation from abroad vs. transmission of CPE within UK healthcare and community settings contributes to the UK CPE picture.2
Local CPE cluster investigation led us to analyse CPE carriage over time in relation to mechanism of resistance and speciality, with the aim of potentially identifying inter-species horizontal carbapenemase gene transfer.
2. Methods
All CPE isolates over a four year period, April 2013 to March 2017, were analysed.
We compared clusters of same-species-same- mechanism combinations with clusters of same- mechanism-any-species combinations.
We focused our analysis on four specialities that bore the highest burden of CPE cases: Intensive Care Units (ICU), Medicine, Renal and Vascular, analysing CPE cases over time.
A cluster was defined as more than or equal to three cases over a period of a month in a single speciality.
4. Discussion
IPC efforts have focussed on same-mechanism-same-species CPE clusters locally.
However, our findings study suggest unidentified plasmid-mediated transfer of carbapenemases resulting in multiple undetected same-mechanism-any-species clusters.
The renal wards are the most common areas affected by both same-species-same-mechanism and same-mechanism-any-species clusters.
Our results indicate that a comprehensive approach to preventing the transmission of CPE should consider the possibility of horizontal spread of carbapenemases between bacterial species.
We have widened our approach to preventing the transmission of CPE, by considering same-mechanism-any-species analysis in our cluster investigations.
3. Results
23 same-species-same-mechanism clusters were found in the period April 2013 to March 2017 with 52% (12/23) Klebsiella pneumoniae NDM and 30% (7/23) K. pneumoniae OXA-48 being the most common combinations
The speciality of Renal bore the highest burden, with 43% of clusters (10/23), of which 40% (4/10) were K. pneumoniae NDM and 60% (6/10) K. pneumoniae OXA- 48
41 same-mechanism-any-species clusters were identified over the same period, with 56% (23/41) OXA- 48 and 37% (15/41) NDM related clusters, with the speciality of Renal again bearing the highest burden, with 49% (20/41) of clusters, 25% (5/20) of which were NDM, and 75% (15/20) of which were OXA-48.
References
Public Health England. English surveillance programme for antimicrobial utilisation and resistance (ESPAUR) report. 2016
Findlay J., Hopkins KL., Alvarez-Buylla A., et al. Characterization of carbapenemase-producing Enterobacteriaceae in the West Midlands region of England: J Antimicrobial Chemother. 2017; 72(4):
Disclosures: JO is a consultant to Gama.