Clinical Microbiology and Antimicrobial Chemotherapy. 2025; 27(3):359-368
To study the antimicrobial resistance and clonal diversity of vancomycin-resistant E. faecium in hematology.
Vancomycin-resistant E. faecium (VR-E. faecium) isolated from the blood culture of patients in six hospitals of Russia (2005–2023). Antimicrobial susceptibility of VR-E. faecium were determined by serial broth micro dilution was (CLSI, 2024), to tigecycline assessed according to EUCAST, 2025. Vancomycin-resistance genes (vanA, vanB) in VR-E. faecium were detected by multiplex PCR. Genotyping of VR-E. faecium was performed by MLST.
During the study period, 465 strains of E. faecium were isolated from blood culture, of which 122 (26.3%) were VR-E. faecium. The detection rate of VR-E. faecium increased from 13.1% (2005– 2011) to 59% (2018–2023, p = 0.0015). The majority of VR-E. faecium had the vanA genes (79.5%), while the vanB genes were detected in 20.5% of VR-E. faecium. All VR-E. faecium were susceptibledose dependent to daptomycin. The daptomycin MIC value of 4 μg/ml was determined in 16.4% of VRE. faecium and increased to 20.7% in 2018–2023. One (0.8%) VR-E. faecium strain was resistant to linezolid. All VRE. faecium isolates remained susceptible to tigecycline. A total of 24 sequence types (STs) belonging to clonal complex CC17 were detected. The predominant sequence types were ST80 (30.3%), ST17 (18.9%), and ST78 (13.1%). In 2023, a new ST2470 was registered in the pubMLST database. From 2018 to 2023, the proportion of ST80 increased to 62.1%, while ST17 and ST78 decreased to 13.8% and 5.2% respectively. vanA VR-E. faecium significantly more often belonged to ST80 (37.1% vs. 4%) and ST78 (15.5% vs. 4%) compared to vanB VR-E. faecium, which showed the predominance of ST17 (48% vs. 11.3%). VRE. faecium ST80 isolates exhibited significantly higher rates of daptomycin MICs of 4 μg/ml (21.6% vs. 8.7% and 6.2% for ST17 and ST78, respectively), and higher tetracycline resistance (64.9% vs. 4.3% and 6.3%) compared to ST17 and ST78. Streptomycin resistance was highest in ST78 (68.8%) compared to ST80 and ST17 (27% and 21.7% respectively).
In hematology, an increase in the frequency of VR-E. faecium was observed. Susceptibility to daptomycin, linezolid, and tigecycline was preserved among all studied VR-E. faecium. VR-E. faecium demonstrated significant clonal diversity and evolution during spread. Resistance profiles varied significantly among strains belonging to different STs.