Background
The Infectious Diseases Society of America convened an international, interdisciplinary work group to update its 1999 guidelines regarding uncomplicated urinary tract infections in women. This guideline restricts its recommendations to premenopausal, nonpregnant women without urologic conditions or medical comorbidities.
Conclusions
Fully 75%-95% of uncomplicated UTIs reflect infection with Escherichia coli. Other common pathogens are mostly gram-negative such as Proteus mirabilis and Klebsiella pneumoniae. Staphylococcus saprophyticus is the more common gram-positive agent. Community-acquired methicillin-resistant S. aureus (MRSA) remains very rare.
The selection of antibiotics for uncomplicated UTIs should reflect patient presentation, allergies, and history of adherence in addition to local resistance patterns, drug cost, and tolerance to treatment failure.
The rise in resistant urinary pathogens in the ambulatory setting has complicated effective therapeutic treatment options, as well as mandated consideration of the ecologic impact of widespread use of antimicrobials for a commonly occurring infection.
Local resistance patterns based on hospital antibiograms often are not useful guides for ambulatory empiric therapy as the data are skewed by complicated inpatient infections and patients with substantial comorbid conditions.
Travel outside the United States or use of trimethoprim/sulfa in the preceding 6 months are risk factors for resistance to trimethoprim/sulfa in patients with uncomplicated UTIs.
The low rates of resistance to nitrofurantoin and fosfomycin are felt to be secondary to their minimal effects on fecal flora.
Treatment with cephalosporins is associated with subsequent infection with resistant Enterococcus and other beta-lactam–resistant organisms.
Fosfomycin is active against many resistant organisms such as vancomycin-resistant Enterococcus, MRSA, and beta-lactamase–producing agents. The lack of clinical studies limits the strength of recommendations for use of this agent in patients with multidrug resistant infections.
Implementation
Local prevalence of pathogen resistance greater than 20% to a specific antibiotic precludes that agent’s use for empiric therapy of lower-tract infections.
Ampicillin or amoxicillin should not be used for empiric therapy of lower-tract infections because of their limited efficacy and high prevalence of pathogen resistance.
While a 3-day course of a fluoroquinolone is very effective for uncomplicated cystitis, this class of agent should be used for more complicated presentations to reduce the ecologic impact on community flora.
Nitrofurantoin, 100 mg BID for 5 days, is equivalent in efficacy to 3 days of trimethoprim/sulfa and represents an appropriate initial choice of therapy for cystitis because of low rates of resistance and low impact on microbiologic flora.
If local resistance is under 20% of isolates, trimethoprim-sulfa, one double-strength BID for 3 days, is an appropriate choice for empiric therapy of bladder infections.
While less effective than nitrofurantoin and trimethoprim sulfa, a single 3-g dose of fosfomycin trometamol can be an appropriate choice because of resistance profiles and low ecologic impact.
Beta-lactam agents can be useful treatment agents for cystitis when other agents are not appropriate for a particular patient’s presentation.
Nitrofurantoin and fosfomycin do not attain effective tissue levels in the kidney and should not be used in patients with cystitis who may also have pyelonephritis. Such patients often have bladder symptoms for nearly a week, have unverified subjective fever, or vague flank discomfort.
Patients with suspected pyelonephritis always should have a culture and sensitivity to confirm appropriateness of therapeutic interventions.
A course of a fluoroquinolone antibiotic for 7 days, if local resistance is under 10%, is appropriate for empiric therapy of presumed upper-tract infections in ambulatory patients. If resistance if greater than 10%, fluoroquinolone therapy should start with an additional, single dose of a parenteral antibiotic such as a 1-g dose of ceftriaxone or an aminoglycoside to provide coverage while awaiting results of urinary culture.
Patients hospitalized for pyelonephritis should receive initial treatment with parenteral antibiotics. Aminoglycosides and beta-lactams may be more effective when combined with another agent for initial therapy of these upper-tract infection patients.
Reference
“International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women” (Clin. Infect. Dis. 2011;52:e103-20).
Dr. Golden is professor of medicine and public health and Dr. Hopkins is program director for the internal medicine/pediatrics combined residency program at the University of Arkansas, Little Rock. Write to Dr. Golden and Dr. Hopkins at imnews@elsevier.com.