Surveillance and Characteristics of Vancomycin-Resistant Enterococcus Isolates in a Chinese Tertiary Hospital in Shenzhen, 2018 to 2024.

Objective: To investigate the prevalence and characteristics of vancomycin-resistant Enterococcus (VRE) isolates in a Chinese tertiary hospital in Shenzhen.

Methods: A hospital-based retrospective epidemiological survey of Enterococcus was conducted over a 6.5-year period, from January 2018 to June 2024. The VRE isolates were identified and subjected to screening for the six van genes and multi-locus sequence typing (MLST) genotyping. The clinical characteristics, antimicrobial susceptibility profiles and molecular features were subjected to analysis.

Results: A total of 34 non-duplicate VRE isolates were identified, comprising 32 vancomycin-resistant Enterococcus faecium (VREfm) and 2 vancomycin-resistant Enterococcus faecalis (VREfa) strains. Since its initial isolation in 2022, there has been an observable increase in the detection rate of VRE. The detection rate of VRE between 2022 and 2024 (until June) was 0.3%, 4.8%, and 8.6%, respectively. The majority of the VRE strains were isolated from urine (25/34, 73.5%), and the highest detection rate (9.1%) of VRE infections was observed in the patients aged ≥75 years. In excess of 90% of VRE isolates exhibited resistance to ciprofloxacin (97.1%) and levofloxacin (97.1%), followed by ampicillin (94.1%) and penicillin (94.1%). The non-susceptible rate was observed to be low for linezolid (2.9%) and tigecycline (5.9%). Of the 29 VREfm isolates preserved and tested, 28 were found to harbour the vanA gene. A total of six STs were identified among the 29 VREfm isolates, with ST80 (16/29, 55.2%) being the predominant. The ST80 remained the most prevalent clone until the introduction of ST78 in May 2023, at which point these two clones became the most prevalent.

Conclusion: There has been an observable increase in the prevalence of VRE in our hospital since 2022. Furthermore, an ongoing outbreak of ST80 and ST78 VREfm with vanA-harboring plasmid was identified. It is imperative that continuous surveillance be conducted in order to inform public health interventions.