Background: 2011 IDSA guidelines for acute uncomplicated cystitis (AUC) recommend trimethoprim-sulfamethoxazole (T-S), fosfomycin tromethamine (FOS), or nitrofurantoin (NF) as first-line therapies. Further, benchmark community E. coli resistance rates indicating a need for change in empiric therapy are 20% for T-S, 10% for ciprofloxacin (CP), and not specified for FOS. However, guidelines also recommend empiric therapy for AUC (no urine culture) and community-acquired AUC is not reportable. Thus, tracking temporal trends in E. coli antimicrobial resistance among isolates from AUC is challenging, especially for FOS, since many laboratories do not routinely perform FOS susceptibility testing. We collected and analyzed longitudinal data on rates of antimicrobial resistance among uropathogenic E. coli from AUC research subjects ages 18 to 40, seen in the UTI Research Clinic (URC), a university-based health clinic, between 1998 and 2014. Starting in 2011, FOS testing was added, using disk diffusion testing to determine sensitivity for E. coli or E. faecalis and E-test for other uropathogens (sensitivity = ²64 µg/mL).
Methods: Using standard methods, urine culture and sensitivity were performed on 2003 consecutive urine specimens collected from women enrolled in 11 different UTI studies at the URC.
Results: E. coli resistance rates for amoxicillin-clavulanate (AMC), T-S, CP, NF and FOS are as shown in the figure. The table shows percent sensitivity to FOS of non-E. coli uropathogens isolated in the past 4 years.
Conclusion: In studies of AUC in the URC, E. coli resistance rates for T-S have exceeded IDSA guideline benchmark rates for the past 2 years, but resistance to NF and FOS remain low. Most non-E. coli uropathogens isolated in the past 4 years were susceptible to FOS, except S. saprophyticus (100% resistant). These data support IDSA guidelines recommending NF or FOS for first-line therapy of AUC, but suggest caution in the use of T-S.
M. Cox, None
A. Silvestroni, None
T. Hooton, None