Review Question - QID 107151

The patient in this vignette is exhibiting symptoms classic for a urinary tract infection, or cystitis. The most common cause of uncomplicated cystitis and pyelonephritis is E. coli.

Seventy-five to ninety-five percent of uncomplicated cystitis in women is caused by E. coli. If E. coli is not the causative bacteria, S. saprophyticus (second most common), K. pneumoniae, and P. miralibis are most commonly encountered. Risk factors include recent sexual intercourse, spermicide use, and a personal or family history of previous UTIs.

Colgan et al. review the diagnosis and treatment of acute uncomplicated cystitis. Uncomplicated cystitis occurs in women of childbearing age without comorbidities or urologic abnormalities (if such comorbidities are present, it is referred to as complicated cystitis). Urinalysis is recommended for the diagnosis of uncomplicated cystitis, but urine culture is not indicated. Empiric treatment with nitrofurantoin, TMP/SMX, or fosfomycin is recommended.

Sanchez et al. examined E. coli isolates from more than 12 million U.S. outpatients between 2000-2010 for changes in resistance patterns. Resistance rose for ciprofloxacin (3% to 17.1%) and TMP-SMX (17.9%-24.2%), while nitrofurantoin (0.8% to 1.6%) and ceftriaxone (0.2% to 2.3%) showed minimal increases.

Incorrect Answers:
Answers 1, 3, and 4: Although these are the next most common causes of urinary tract infections, E. coli is more common overall.
Answer 2: Chlamydia trachomatis along with Neisseria gonorrhea are common sexually transmitted bacteria that cause urethritis in men and women. The absence of abnormal vaginal discharge or bleeding makes this diagnosis less likely.