Therapeutic Outcomes of Oral Antibiotics for the Treatment of Methicillin-Resistant Staphylococcus aureus Urinary Tract Infections: A Multisite, Retrospective Cohort Study of Linezolid, Trimethoprim–Sulfamethoxazole and Doxycycline

Background: Methicillin-resistant Staphylococcus aureus (MRSA) urinary tract infections (UTIs), while relatively uncommon, pose a unique challenge in treatment as only specific intravenous (IV) options are typically utilized, with the efficacy of oral antimicrobials being poorly defined. Methods: The multi-site retrospective cohort study described herein therefore aims to characterize outcomes associated with oral administration of linezolid, trimethoprim-sulfamethoxazole (TMP-SMX), or doxycycline for the treatment of MRSA UTIs. Study participants were adults with culture-positive MRSA UTIs receiving one of the three oral therapies. Exclusion criteria included polymicrobial UTI, concomitant MRSA outside the urinary tract, receipt of non-study anti-MRSA agents for greater than or equal to 50% of treatment, less than 48 h of the oral study drug, and/or prostatitis. The primary outcome was clinical cure defined as a composite of symptom resolution, no readmission within 30 days of discharge attributable to UTI, and no change in therapy due to treatment failure. Secondary outcomes included antibiotic discontinuation because of adverse effects (AEs). Results: Overall, patients attained a clinical cure rate from MRSA UTI of 78.8%, 80.0%, and 94.4% when treated with linezolid, TMP-SMX, or doxycycline, respectively. Conclusions: While there were no observed differences between the clinical cure rates of the three antimicrobials studied, the high clinical cure rate coupled with low rates of AEs may support these oral therapies for the treatment of MRSA UTIs, but further investigation is required.