Treatment of Vancomycin-Resistant Enterococci Urinary Tract Infections

Introduction to Treatment Options

The American College of Microbiology recommends linezolid 600 mg every 12 hours as an appropriate treatment option for complicated or upper tract VRE urinary tract infections, though it should be reserved for these cases rather than uncomplicated cystitis, where oral alternatives like fosfomycin or nitrofurantoin are preferred first-line agents 1, 2

For uncomplicated VRE cystitis, the Infectious Diseases Society of America prioritizes oral agents with better urinary concentration, including fosfomycin 3 g PO as a single dose (weak recommendation, 2D evidence) and nitrofurantoin 100 mg PO every 6 hours for 7 days (weak recommendation, 2D evidence) 1, 2
Linezolid 600 mg IV or PO every 12 hours is recommended as a strong option (strong recommendation, 1C evidence) for complicated VRE UTI or pyelonephritis 1, 2

The Centers for Disease Control and Prevention notes that for VRE bacteremia associated with UTI, linezolid showed mortality rates of 32.8% compared to 35.7% with daptomycin (RR 1.24, 95% CI 1.02-1.50) 1, 2

The European Society of Clinical Microbiology and Infectious Diseases recommends high-dose daptomycin 8-12 mg/kg/day, particularly for VRE bacteremia (weak recommendation, 2C evidence) 1, 2
Daptomycin and linezolid show comparable microbiologic cure rates (93% vs 91%, RR 0.95, 95% CI 0.73-1.25) 2, 3

The American College of Microbiology recommends obtaining susceptibility testing before initiating therapy, as approximately 60% of E. faecium are vancomycin-resistant with variable ampicillin susceptibility 4, 5

The Infectious Diseases Society of America guidelines warn that linezolid has been associated with serotonin syndrome in patients treated concurrently with serotonin reuptake inhibitors, and thus alternative therapies should be considered for patients on multiple serotonergic medications 6
Linezolid carries significant risk of serotonin syndrome when combined with serotonergic agents, including SSRIs, SNRIs, tricyclic antidepressants, and bupropion, highlighting the need for careful risk assessment in patients on these medications 7, 6

If linezolid is unavoidable, the patient should be monitored for serotonin syndrome symptoms every 4-6 hours during the first 72 hours, including neuromuscular hyperactivity, autonomic instability, and mental status changes 6, 7, 8
The patient should be informed of the risks of serotonin syndrome and provide informed consent before initiating linezolid therapy, as recommended by the Infectious Diseases Society of America 6

Daptomycin 8-12 mg/kg/day is an alternative to linezolid for complicated VRE UTI, with comparable microbiologic cure rates and no risk of serotonin syndrome, but requires monitoring for rhabdomyolysis, neuropathy, and eosinophilic pneumonia 6
Ampicillin-based therapy is considered the drug of choice for ampicillin-susceptible enterococcal UTIs, including VRE, with no drug-drug interactions with psychiatric medications 6, 8

Patients on serotonergic medications should have a explicit risk-benefit discussion before initiating linezolid therapy, and alternative therapies should be considered to avoid the risk of serotonin syndrome 7, 6