Ana Janjusevic, Rajna Minic, Ivana Cirkovic
Intestinal VREfm colonisation in Serbian university hospitals was characterised by a genetically diverse but predominantly CC17-associated population structure. These findings highlight intestinal colonisation as an important reservoir of hospital-adapted VREfm lineages and support the need for intensified surveillance and targeted monitoring of high-risk patients.
BACKGROUND: Intestinal colonisation with vancomycin-resistant Enterococcus faecium (VREfm) represents an important reservoir for hospital transmission and subsequent infection. The aim of this study was to investigate the molecular epidemiology and population structure of VREfm colonising isolates among high-risk inpatients in three university hospitals in Serbia. To our knowledge, this study provides the first whole-genome sequencing (WGS)-based insight into the molecular epidemiology of intestinal VREfm colonisation in Serbia and one of the first such studies from Southeast Europe.
METHODS: A total of 29 VREfm isolates obtained through intestinal carriage screening in three university hospitals in Belgrade were analysed by WGS. Sequence types (STs) were assigned using the PubMLST database. Genetic relatedness was assessed using goeBURST analysis based on the global Enterococcus faecium MLST database.
RESULTS: MLST identified 16 STs among 29 isolates, indicating considerable genetic diversity. The most frequent STs were ST203 (n = 7) and ST125 (n = 5), followed by ST18, ST80, and ST375 (n = 2 each), while the remaining STs were represented by singletons. goeBURST analysis demonstrated that 27/29 isolates belonged to the hospital-associated clonal complex CC17, with most STs showing close allelic relationships to internationally disseminated CC17-associated lineages, including ST117, ST18, ST80, ST17, and ST78. Four novel sequence types (ST2858, ST2978, ST3161, and ST3162) were identified, with ST3162 containing a novel atpA allele (atpA-234). Two isolates (ST545 and ST2858) belonged to distant non-CC17 lineages.
CONCLUSIONS: Intestinal VREfm colonisation in Serbian university hospitals was characterised by a genetically diverse but predominantly CC17-associated population structure. These findings highlight intestinal colonisation as an important reservoir of hospital-adapted VREfm lineages and support the need for intensified surveillance and targeted monitoring of high-risk patients.