Increase of vancomycin-resistant Enterococcus faecium strain type ST117 CT71 at Charité - Universitätsmedizin Berlin, 2008 to 2018

Abstract

In addition to an overall rise in vancomycin-resistant Enterococcus faecium (VREfm), an increase in certain other strain types has been reported in Germany over the past few years. Outbreak analyses at Charité - Universitätsmedizin Berlin revealed the frequent occurrence of VREfm ST117 CT71 isolates in 2017 and 2018. To investigate whether ST117 CT71 have emerged in recent years or whether these strains have been circulating for a longer time, we retrospectively analyzed non-outbreak strains that occurred between 2008 and 2018 to identify frequent sequence types (STs) and cluster types (CTs). Methods In total, 120 VREfm isolates obtained from clinical and surveillance cultures from the years 2008, 2013, 2015, and 2018 were analyzed. Thirty isolates per year comprising the first 7 to 8 non-outbreak isolates of each quarter of the respective year were sequenced using whole genome sequencing. MLST and cgMLST were determined as well as resistance genes and virulence factors. Risk factors for VREfm ST117 were analyzed in a multivariable analysis with patient characteristics as possible confounders. Results The percentage of VREfm of type ST117 increased from 17% in 2008 to 57% in 2018 (p=0.012). In 2008, vanA genotype accounted for 80% of all ST117 isolates compared to 6% in 2018. VanB CT71 first appeared in 2018 and predominated over all other ST117 at 43% (p<0.0001). The set of resistance genes and virulence factors in CT71 (msrC, efmA, ermB, dfrG, and aac(6')-Ii) and virulence factors (acm, esp, hyl, ecbA and sgrA) was also found in other ST117 non-CT71 strains, mainly in CT36. The study population did not differ among the different calendar years analyzed in terms of age, gender, length of stay, or ward type (each p>0.2). Conclusion This study revealed an increase in ST117 strains from 2008 to 2018, accompanied by a shift toward CT71 strains with the vanB genotype in 2018. We did not detect resistance or virulence traits in CT71 that could confer survival advantage compared to other CTs among ST117 strains. To date, it is not clear why ST117 and in particular strain type ST117 CT71 predominates over other strains.

Impact of discontinuing contact precautions and enforcement of basic hygiene measures on nosocomial vancomycin-resistant Enterococcus faecium transmission

“…Interestingly, ST117/CT71 and ST117/CT36 were already present in the 2016 cohort and became the most dominant clones in 2019, while ST117/CT469 and ST117/CT2558 were diminished in the 2019 population. Hospitals in other regions of Germany have reported similar observations (4,20,21). The ST117 E. faecium clone appears to be heterogeneous, and, for the time being, there is no plausible explanation for this clonal shift.…”

“…The prevalence of vancomycinresistant E. faecium (VREfm) in Germany has risen dramatically over the past years (4). At the same time, the genetic variety of isolates has decreased, resulting in a few dominant clones causing the vast majority of VREfm infections (5)(6)(7).…”

First report of nosocomial outbreak of vancomycin-resistant Enterococcus faecium infection among COVID-19 patients hospitalized in a non-intensive care unit ward in Slovakia

“…One of the two samples from this clone was isolated from haemoculture, and the patient with positive haemoculture sample died during the study. Isolated clones from ward B belonged to the vanB-ST117 lineage; this clone is known to have caused nosocomial outbreaks in several European countries (25)(26)(27). Due to a lack of information, we could not evaluate the prevalence of VRE infections caused by these lineages in Slovakia.…”

First Report of Nosocomial Outbreak of Vancomycin-Resistant Enterococcus Faecium Infection Among COVID-19 Patients Hospitalized in a Non-Intensive Care Unit Ward in Central Europe

“…One of the two samples from this clone was isolated from haemoculture, and the patient with positive haemoculture sample died during the study. Isolated clones from ward B belonged to the vanB-ST117 lineage; this clone is known to have caused nosocomial outbreaks in several European countries (24)(25)(26). Due to a lack of information, we could not evaluate the prevalence of VRE infections caused by these lineages in Slovakia.…”