Acute cystitis

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This page is for adult patients; see urinary tract infection (peds) for pediatric patients.


Anatomy of the bladder (male)

Genitourinary infection

(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra.
Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.

"UTI" frequently refers specifically to acute cystitis, but may also be used as a general term for all urinary infections; use location-specific diagnosis.


  • Relapse
    • Recurrence of symptoms within month despite treatment
      • Caused by same organism and represents treatment failure
  • Reinfection
    • Development of symptoms 1-6mo after treatment
    • Usually due to a different organism
    • If patient has >3 recurrences in 1 yr consider tumor, calculi, diabetes
    • For menopausal or postmenopausal women with recurrent infection consider empiric treatment for genitourinary syndrome of menopause (GSM)[1]

Risk Factors

  • Anatomic abnormality of urinary tract or external drainage system
    • Indwelling urinary catheter, stent
    • Nephrolithiasis, neurogenic bladder, polycystic renal disease, recent instrumentation
  • Recurrent acute cystitis
  • Advanced age in men (BPH, recent instrumentation, recent prostatic biopsy)
  • Nursing home residency
  • Neonatal
  • Comorbidities (DM, sickle cell disease)
  • Pregnancy
  • Immunosuppression (AIDS, immunosuppressive drugs)
  • Advanced neurologic disease (CVA with disability, Spinal Cord Injuries)


Clinical Features



Suspect pyelonephritis, infected kidney stone, or other disease process in patients who have inadequate or atypical response to treatment

Differential Diagnosis


Acute Pelvic Pain

Differential diagnosis of acute pelvic pain








Urine with pyuria.

Urine Analysis (UA)

WBC count

  • WBC >5 in patient with appropriate symptoms is diagnostic
    • Lower degrees of pyuria may still be clinically significant in presence of symptoms
      • False negative may be due to: dilute urine, systemic leukopenia, obstruction, recent antibiotic use with incomplete treatment
    • WBC 1-2 with bacteriuria can be significant in men
    • High WBCs w/o bacteria, consider TB, Chlamydia, Appendicitis

Leukocyte Esterase

  • Found in PMNs
  • High sensitivity
  • Low specificity


  • Very high specificity (>90%) in confirming diagnosis
  • Low sensitivity (enterococcus, pseudomonas, acinetobacter are not detected)

Urine Culture

  • Indicated for:
    • Complicated acute cystitis
    • Pyelonephritis
    • Pregnant women
    • Children
    • Adult males
    • Relapse/reinfection

Blood Culture


  • Consider local resistance patterns (if >10-20% use a different agent)
  • Avoid use of fluoroquinolones for uncomplicated cystitis if possible
  • Consider phenazopyridine for dysuria symptoms
    • 100-200mg TID after meals x 2 days for pain control (bladder analgesic)
    • Warn of discoloration of urine and tears. Don’t wear contact lens due to risk of staining.[3]
Complicated if
  • Symptoms >7days
  • Diabetes mellitus
  • Urinary tract infection in previous 4wk
  • Men
  • >65 years old
  • Women who use spermicides or diaphragm
  • Relapse
  • Pregnancy


Women, Uncomplicated

  • Nitrofurantoin ER 100mg BID x 5d, OR
  • TMP/SMX DS (160/800mg) 1 tab BID x 3d, OR
  • Cephalexin 250mg QID x 5d, OR
  • Ciprofloxacin 250mg BID x3d
    • Avoid using fluoroquinolone for the first-line treatment of uncomplicated urinary tract infections (UTIs) in women.[4]
  • Fosfomycin 3 g PO once
    • Lower clinical and microbiologic success compared to nitrofurantoin TID for 5 days [5]

Women, Complicated

Women, Concern for Urethritis


Inpatient Options



  • Admit for inability to tolerate PO


  • Consider admission for period of observation and/or culture results

Special Populations


  • TMP-SMX resistance is increased due to its use in PCP pneumonia prophylaxis
  • Most acute cystitis is caused by typical pathogens or common STI organisms

Pregnant Women

  • New ACOG guidelines: If asymptomatic, get a culture and only treat if >100k CFUs[6]

See Also


  1. Winter et al, UTIs and Estrogen: the Overlooked Link
  2. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.
  3. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.
  4. Choosing Wisely. American Urogynecologic Society.
  5. Huttner, A., Kowalczyk, A., Turjeman, A., Babich, T., Brossier, C., Eliakim-Raz, N., … Harbarth, S. (2018). Effect of 5-Day Nitrofurantoin vs Single-Dose Fosfomycin on Clinical Resolution of Uncomplicated Lower Urinary Tract Infection in Women: A Randomized Clinical Trial. JAMA: The Journal of the American Medical Association, 319(17), 1781–1789.
  6. Urinary Tract Infections in Pregnant Individuals Clinical Consensus. Number 4, August 2023.