Linezolid to treat urinary tract infections caused by vancomycin-resistant Enterococcus

Abstract

Background: Vancomycin-resistant Enterococcus can cause urinary tract infection. Linezolid possesses antimicrobial activity against vancomycin-resistant Enterococcus but has limited urinary excretion. Minimal data demonstrate efficacy of linezolid for treatment of urinary tract infections.

Objective: The main aim of this study is to compare post-treatment outcomes of linezolid to other antibiotics with vancomycin-resistant Enterococcus activity in the treatment of urinary tract infection caused by vancomycin-resistant Enterococcus.

Methods: A retrospective cohort of inpatients within Veterans Health Administration facilities with urinary tract infection caused by vancomycin-resistant Enterococcus was created. Patients with vancomycin-resistant Enterococcus isolated from urine cultures and chart documentation meeting criteria for urinary tract infection were identified. Demographics, comorbidity, treatments, and post-treatment outcomes were extracted from the electronic health record. Outcomes were compared between patients treated with linezolid and alternative antibiotics possessing vancomycin-resistant Enterococcus activity 14 days after treatment completion. Logistic regression adjusted for covariates associated with each outcome.

Results: Of 4,683 patients with a positive vancomycin-resistant Enterococcus culture, 624 (13%) met criteria for chart review, and 92 (15%) had documentation of urinary tract infection symptoms and treatment. The primary reason for exclusion was asymptomatic bacteriuria (64%). Patients had high Charlson Comorbidity Scores (mean = 8.7; standard deviation (SD) = 3.3), and 70% were located on general medical/surgical wards on the day of culture collection. Linezolid was prescribed in 54 (59%) cases. No difference between linezolid and comparator antibiotics were observed in re-initiation of antibiotics for vancomycin-resistant Enterococcus urinary tract infection (9% and 5% respectively (p = 0.56), (adjusted odds ratio (OR) = 1.90; 95% confidence interval (CI) = 0.34-10.63)), recurrent positive vancomycin-resistant Enterococcus culture (4% and 11%, respectively (p = 0.23), (adjusted OR = 0.36; 95% CI = 0.05-2.31)), or mortality (7% and 3%, respectively (p = 0.39) (adjusted OR = 2.96; 95% CI = 0.37-41.39)).

Conclusion: Most patients with vancomycin-resistant Enterococcus identified on urine culture were asymptomatic. Linezolid appears effective as comparator antibiotics for the treatment of mild vancomycin-resistant Enterococcus urinary tract infection.

Keywords: Enterococcus; Infectious diseases; antibiotic resistance; linezolid; urinary tract infections.

Figure 1.

Flow diagram for identification of patients with UTI caused by VRE cohort. CDW: corporate data warehouse; UTI: urinary tract infection; VA: veterans affairs; VRE: vancomycin-resistant Enterococcus. Incomplete data refers to patients who did not have adequate data needed for identification within the electronic medical record. All timeframes refer to the date when the urine culture that grew VRE was collected.