Enterococcus faecium multicenter antimicrobial resistance surveillance in Tunisia (2010-2022): high vancomycin resistance rates and linezolid resistance emergence.

BACKGROUND: Vancomycin-resistant Enterococcus faecium is classified among World Health Organization priority pathogens for Research and development of new antibiotics. This study presents the results of 13-year surveillance of antibiotic resistance in E. faecium, with a specific focus on vancomycin and linezolid resistance in thirteen university hospitals across various regions of Tunisia. METHODS: All participating laboratories followed a standardized methodology for clinical sample culture, bacterial identification, antibiotic susceptibility testing according to CA-SFM guidelines, result interpretation, epidemiological data collection. Additionally, they implemented quality controls. FINDINGS: During the surveillance period, 2,931 E. faecium isolates were collected, predominantly from urine (49.1%) and blood cultures (24%), with high prevalence in Surgery Departments (30.3%) and Intensive Care Units (23.6%). Resistance rates were high for ampicillin (87.1%), erythromycin (93.6%), gentamicin (62.8%) and vancomycin (26%). Since 2019, six linezolid-resistant isolates have been isolated and only one isolate resistant to tigecycline was identified in 2021. Vancomycin resistance had significant upward trend since 2012, peaking at 38.1% in 2017. It was significantly associated to gentamicin (84.9% vs. 53.8%) (p<0.0001) and erythromycin95.8% vs. 89.6%) (p=0.0001) in a five year period (2018 - 2022). CONCLUSION: This worrying situation requires deeper investigations to develop adapted strategies with targeted measures in high-risk departments.