• Infection of urinary bladder

Also called

  • Lower urinary-tract infection (UTI)
  • Cystitis
  • Acute cystitis

ICD-9 codes

  • 595.0 acute cystitis
  • 599.0 UTI, site not specified
  • 041.4 Escherichia coli
  • V13.02 personal history, urinary (tract) infection

Who is most affected

  • Eight times more common in women than in men (due to shorter urethra)


  • Common in women
  • The 15th most common diagnosis made during family-clinician visits
  • The most common nosocomial infection


  • Most commonly E. coli (75%-90% cases of acute uncomplicated cystitis).

Likely risk factors

  • Most important risk factors for acute cystitis in young women: History of previous episodes of cystitis and frequent or recent sexual activity
  • Sexual activity factors that increase risk for UTI include: Recent sexual intercourse and use of diaphragm or condom with spermicide
  • Postvoid residual volumes >30 mL associated with increased incidence of recurrent UTIs
  • Risk factors for complicated UTI include: Pregnancy and diabetes mellitus
  • Indwelling urinary catheter
  • Nephrolithiasis
  • Neurogenic bladder
  • Polycystic renal disease
  • Immunosuppression
  • Recent urinary-tract instrumentation

Chief concern

  • Dysuria, frequency, urgency, burning (pain usually referred to distal urethra), nocturia, hematuria, lower abdominal pain, voiding small volumes and incontinence.
  • Usually not accompanied by fever or chills.

History of present illness

  • Usually abrupt onset.
  • Ask about vaginal discharge or vaginal irritation, which makes diagnosis of UTI less likely.
  • Back pain and fever are nonspecific but suggest possibility of pyelonephritis.
  • Elderly patients with UTIs may have atypical symptoms.

General physical exam

  • Patients are usually afebrile.


  • Suprapubic tenderness may occur.

Making the diagnosis

  • Presumptive diagnosis of UTI can be made in sympto­matic women if there is either: dysuria and frequency without vaginal symptoms; dipstick urinalysis showing positive nitrite OR positive leukocyte esterase
  • Definitive diagnosis based on results of urine culture: Infectious Diseases Society of America consensus definition of cystitis is urine culture with ≥1,000 colony forming units (CFU)/mL; use of traditional standard (100,000 CFU/mL) results in frequent missed diagnoses.
  • Neither dipstick urinalysis nor clinical decision rule can reliably rule out suspected UTI in patients with either dysuria, nocturia, cloudy urine, or offensive-smelling urine.
  • Women with history of recurrent UTIs may accurately self-diagnose new UTI
  • Elderly patients with UTIs may have atypical symptoms.

Rule out

  • Vulvovaginitis
  • Interstitial cystitis/painful bladder syndrome
  • Pelvic inflammatory disease
  • Acute urethritis due to sexually transmitted diseases
  • Radiation cystitis
  • Hemorrhagic cystitis caused by medications
  • Urine contamination with normal flora (Lactobacillus, Corynebacterium, Staphylococcus epidermidis)

Testing to consider

  • Testing not required in nonpregnant women with dysuria, frequency, and no vaginal symptoms (likelihood of UTI >90%).
  • Positive urine dipstick for nitrites or leukocyte esterase allows presumptive diagnosis.
  • Urine microscopy can show red cells, white cells, or bacteria.
  • Urine culture useful if complicated UTI, pregnancy, male patients, or clinical suspicion despite negative urine dipstick
  • Imaging studies may be useful in selected cases (i.e., men with signs of upper UTI).


  • Most women have symptom relief within three days.

Treatment overview

  • For nonpregnant women with uncomplicated UTI:
    • Trimethoprim-sulfamethoxazole (TMP-SMZ) (Bactrim, Septra) 160 mg/800 mg orally b.i.d. for three days recommended as optimal choice for empiric therapy.
    • In areas with >15%-20% E. coli resistance to TMP-SMZ, options include:
      • fluoroquinolones;
      • ciprofloxacin (Cipro) 250 mg orally every 12 hours for three days, ciprofloxacin extended-release 500 mg orally once daily for three days;
      • levofloxacin (Levaquin) 250 mg orally once every 24 hours for three days;
      • nitrofurantoin (Furadantin, Macrobid, Macrodantin, Nitro Macro) 50-100 mg orally q.i.d. or 100 mg orally b.i.d. for seven days, give with food; fosfomycin (Monurol) 3 g with 3-4 oz (90-120 mL) of water orally as single dose.
  • Antibiotic duration
    • Three days of antibiotics is as effective as five to 10 days for symptomatic cure but less effective for bacteriologic cure.
    • Ciprofloxacin for three days is as effective as for seven days in elderly women with uncomplicated UTI.
    • Nitrofurantoin for five days appears as effective as TMP-SMZ for three days.
  • For other populations:
    • For pregnant women with UTI, recommended treatment is seven-day course of nitrofurantoin (but not near term or delivery), amoxicillin, or a cephalosporin.
    • For men with UTI, recommended treatment is fluoroquinolone antibiotic for two weeks.
    • In UTI patients with neurogenic bladder, 14 days of antibiotics is associated with lower relapse rate than three days.
  • Antibiotics may reduce symptom duration in women with dysuria and negative urine dipstick testing.
  • For symptomatic severe UTIs, oral antibiotics appear as effective as IV antibiotics.
  • Routine treatment of asymptomatic bacteriuria not warranted in older women or women with diabetes.
  • Other considerations:
    • Phenazopyridine may provide acute relief of symptoms.
    • Probiotics shown to reduce rate of antibiotic-associated diarrhea.
    • Insufficient evidence to recommend cranberry juice for treatment of UTIs


  • No evidence to support urine culture after treatment in uncomplicated UTI.


  • Cranberry juice may decrease number of symptomatic UTIs in women.
  • Prophylactic antibiotics reduce rate of recurrent UTI during prophylaxis over six to 12 months.
  • Vaginal estrogens might reduce UTIs in postmenopausal women with recurrent UTI.
  • Postcoital voiding may slightly reduce risk for UTI.
  • Vitamin C is associated with reductions in bacteriuria during pregnancy.


  • United States Preventive Services Task Force (USPSTF) recommendations on screening for asymptomatic bacteriuria
    • USPSTF strongly recommends screening all pregnant women for asymptomatic bacteriuria using urine culture at 12-16 weeks’ gestation.
    • USPSTF recommends against routine screening of men and nonpregnant women for asymptomatic bacteriuria.

Dr. Ehrlich is a family physician and Deputy Editor for DynaMed, a database of comprehensive updated summaries covering more than 3,200 clinical topics.