Methods: In a 637-bed university teaching hospital in Montréal, Canada, detection of a new case of a nosocomially acquired KPC-producing Enterobacter cloacae (Ec1) prompted the application of WGS analysis to epidemiologically-linked clinical and surveillance samples harbouring the KPC gene (n=9). blaKPC gene presence was confirmed by PCR. Pulsed-field gel electrophoresis using XbaI, plasmid fingerprinting (pRFLP) using Bgl II and PCR to detect plasmid incompatibility groups (Inc) was conducted. Whole genome sequencing (WGS) was conducted using Illumina technology on a Miseq with assembly using Spades. Analysis of the genomes was conducted by single variant polymorphisms (SVP), MLST and mapping of Tn4401 to a referencing using Bowtie.
Results: In all, 9 isolates from 5 subjects were sequenced: 5 K. pneumoniae, 1 E.coli, 1 K. oxytoca and 2 E. cloacae (Ec1 and the only other known KPC-producing E. cloacae detected at the hospital in the previous year). SNP analysis of Tn4401 and pRFLP revealed 3 transposon types (Tn4401-type1-3), incorporated into 6 distinct plasmids (A1, A2, B1, C1, D1, E1), belonging to IncN, IncP,L/M, IncFllk or IncFIA(H1). Tn4401-type1 was identified in 3 plasmids (A2,D1,E1), found in 3 species, K. pneumoniae, E. cloacae and K. oxytoca. A2, an IncN plasmid, associated with Tn4401-type1 was identified in Ec1 and in a K.pneumoniae suggesting that the isolates are linked.
Conclusion: WGS is a promising tool to aid in investigating and tracking transmission of both organisms and their highly mobile genetic determinants of resistance. As demonstrated here, its application in the setting of nosocomial transmission supports re-thinking of when and how to implement infection control practices and endorses WGS on a larger scale to optimize the management of nosocomial outbreaks.
L. Mataseje, None
M. Mulvey, None
C. Mangat, None
M. Miller, None
B. Lefebvre, None
L. P. Haraoui, None