Category: Professional Posters
Purpose: Urinary tract infections (UTI) caused by Enterobacteriaceae commonly possess Extended Spectrum Beta Lactamases (ESBL) which are typically treated with carbapenem agents (meropenem or ertapenem). Due to the mounting evidence and concern for resistance to these broad spectrum, last-line agents, a new Baycare protocol will automatically including fosfomycin E-testing when a urine isolate is positive for ESBL E. coli (this species accounts for about 70% of all cystitis and is highly susceptible to fosfomycin irrespective of ESBL production).
Methods: This retrospective, IRB-approved, cohort study assessed the impact of the stewardship policy in reducing carbapenem usage for ESBL E. coli UTI without pyelonephritis or bacteremia through several endpoints. Two groups were compared, 80 patients collected pre- and post-implementation of the fosfomycin reflex policy. The inclusion criteria were: age > 18, ESBL positive E coli cystitis treated with at least one dose of definitive therapy, and inpatient admission to one of the four study hospitals within a large Florida health system. Patients were excluded if he/she had pyelonephritis, perinephric abscess, bacteremia/sepsis, carbapenem use for non-UTI indication, allergy to carbapenem or fosfomycin, or if the isolate was not tested for fosfomycin in the post-implementation group. The primary outcome was proportion of patients who received any definitive carbapenem therapy. Key secondary outcomes included median total carbapenem days of therapy (DOT), discharge on IV UTI antibiotics, and median total antibiotic DOT.
Results: Pre-protocol vs post-protocol carbapenem utilization was seen in 59/80 patients (73.8%) and 71/99 patients (71.7%), respectively (95% CI for difference -11.1% to 15.1%, p=0.76). Rates of stepdown in those receiving carbapenems pre- and post-intervention were 15/59 (25.4%) and 35/71 (49.3%) (p=0.004). Median carbapenem DOT in those receiving carbapenems decreased from 8 days to 4 days (95% CI [-5 to -1 days], p=0.001). Median total DOT decreased from 10 days to 8 days (95% CI [-3 to -1 days], (p=0.002). Patients discharged on IV UTI antibiotic therapy decreased from 32/80 (40%) to 23/99 (23.2%) (p=0.016). Median wholesale cost of total UTI antibiotic therapy (US Dollars) was insignificantly decreased (291 pre-protocol vs. 244 post-protocol, 95% CI: -124 to 21).
Conclusion: Implementation of a laboratory policy to automatically E-test ESBL positive E coli for fosfomycin did not reduce the percentage of patients receiving at least one dose of carbapenem treatment. It did, however, result in a larger percentage of stepdown prior to discharge (mostly to fosfomycin); reduction in discharge on intravenous antibiotics for UTI; reduction in carbapenem DOT; and reduction in total antibiotic DOT. Further studies are needed to assess the impact of this protocol on clinical resolution of UTI series; rates of carbapenem-resistant Enterobacteriaceae and/or ESBL isolates; and total cost impact (drug cost plus administration and other downstream estimations).