Increasing Trends of Linezolid Resistant Enterococcus Species in a Tertiary Care Hospital, Islamabad

Abstract

Objective: To conduct a five-year surveillance analysis of the epidemiological trends, demographic distribution and susceptibility patterns of linezolid-resistant Enterococcus (LRE), addressing a critical evidence gap in a region where no prior data are available.

Methodology: A retrospective, cross-sectional study was conducted from January 2020 to December 2024 at the Microbiology Laboratory, Shifa International Hospital, Islamabad. All non-duplicate Enterococcus species isolated from different specimens were included in the study. Demographic, specimen and susceptibility data were retrieved from the laboratory information system (LIS). Enterococcus species that were not susceptible to linezolid (including both intermediate and resistant isolates) were included in LRE. Data analysis was performed using SPSS software version 25.

Results: The overall rate of LRE was 1.7% (n=134/7936) increasing from 0.4 % (n=4/991) in 2020 to 2.1 % (n=34/1653) in 2024, exhibiting a significant upward trend (p value is < 0.001). Among the LRE 64.9% (87/134, 95% CI 56.8-73.0%) of the isolates were from the inpatient department (IPD). Blood cultures (49/134, 36.6%) yielded the highest count. Vancomycin and linezolid resistant Enterococcus (VLRE) accounted for 68.7% (92/134, 95% CI 60.8-76.5%). Antimicrobial susceptibility among both LRE (97.7%, 85/87) and VLRE (98.4%, 61/62) remained highest for tigecycline.

Conclusion: The study revealed an emerging trend of linezolid resistance among Enterococcus particularly in blood cultures and among inpatients, with limited therapeutic options, reflecting the clinical and nosocomial challenges of this resistance.

Keywords: Antimicrobial resistance, Enterococcus susceptibility, Linezolid resistant Enterococcus, Vancomycin resistant Enterococcus.