Background: Understanding the reservoirs and transmission networks of pathogens in a hospital setting is important for tracking and controlling the spread of multi-drug resistant organisms, VRE in particular. The transmission of pathogens may occur through direct patient contact or through the surrounding environment including medical equipment.
In this study, 90 VRE isolates were selected for
Whole Genome Sequencing (WGS) including
35 VRE-positive rectal swabs (S) from hematopoietic cell transplant
recipients, 29 environmental swabs from these
patients bathrooms (B), and 26 swabs from their main rooms (M). We used
SNPs analyses of 100 ortholog concatenated genes to identify VRE clusters and transmission
networks between patients and rooms. We categorized isolates into hospital-acquired
(HA) VRE (after > 48h from admission) and community-acquired (CA) VRE (≤
48h). Patient location and VRE sequence types
(STs) were identified.
Results: HA and CA VRE isolates did not group into distinct clades. Eight different STs were observed, all belonging to the clonal complex CC17. Interestingly, 1 strain belonged to ST494 which is rarely found in the US and bacteremia was observed in patients with VRE belonging to ST736 and ST664 (Fig1). Some VRE strains isolated from patients and their room environment (pairs) were only 40% identical whereas different pairs were 99% identical based on the SNPs found in 100 ortholog concatenated genes. Two pairs were isolated from distinct rooms and time period and were highly genetically identical (Fig1, in pink).
Conclusion: To our knowledge, this is the first study that compares numerous HA and CA VRE as well as VRE strains derived from the environment and immunocompromised patients. Due to the high frequency of mobile genetic elements gain/loss in VRE, hybrid genomes are emerging resulting in a fusion of HA and CA VRE. We showed the potential presence of transmission networks between rooms and VRE transfer to patients. This data will aid in implementing efficient infection control strategies to prevent and control the spread of this opportunistic organism in the hospital setting.
Figure 1. Phylogenetic tree showing the genetic relatedness of the 90 VRE isolates according to SNPs found in 100 ortholog concatenated genes.
L. El Haddad,
G. Otero, None
S. S. Ghantoji, None
M. Stibich, None
R. F. Chemaly, None