This drug is well tolerated and has fewer side effects than the alternatives. Although TMP/SMX has long been the traditional first-line agent for acute cystitis, rising rates of resistance (especially outside the United States) prompted the IDSA/ESCMID to revise this recommendation. However, as long as local resistance patterns do not exceed 20%, TMP/SMX may be considered an alternative first-line agent.

Fosfomycin, administered as a one-time oral 3-g dose, is also classified as a first-line agent. This medication has shown equal clinical efficacy to nitrofurantoin for treatment of UTI, although in vitro bacterial clearance is lower than that of other first-line antibiotics. Fosfomycin demonstrates in vitro activity against vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and extended-spectrum beta-lactamase (ESBL)–producing Gram-negative rods, and has minimal propensity for collateral damage. These features, in combination with the drug’s convenient single oral dose administration, make it an attractive option for treating uncomplicated cystitis.

Fluoroquinolones are highly efficacious in 3-day regimens but have a high propensity for inducing drug-resistant organisms and should be considered a second-line agent for acute uncomplicated cystitis when other UTI agents cannot be used.

Reference

1. Gupta K, Hooton TM, Naber KG, et al. Infectious Diseases Society of America, European Society for Microbiology and Infectious Diseases. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin. Infect. Dis. 2011;52:e103-e120.

Dr. Bernstein is a senior resident in emergency medicine at Yale–New Haven Hospital and is the 2011-2012 EMRA Representative to ACEP’s Clinical Policies Committee.