Urinary tract infection in adults
- Infection of urinary bladder
- Lower urinary-tract infection (UTI)
- Acute cystitis
- 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
- Neurogenic bladder
- Polycystic renal disease
- Recent urinary-tract instrumentation
- 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.
- 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.
- 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:
- 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.