• Common ED presentation.
• 10X more frequent in women.
• 1 in 5 women will have UTI in lifetime.
• Usually uncomplicated, treated with oral antibiotics.

Definitions:

• Pyuria: WBC in urine.
• Bacteriuria: Bacteria in the urine, >10^5 colony forming units (CFU)/mL with culture.

Classification:

• Uncomplicated UTI/Cystitis:
  • Lower tract infection
    • Bladder (cystitis) and urethra (urethritis)
    • Usually healthy non-pregnant women with no anatomical abnormalities
• Complicated UTI:
  • Upper tract infection
    • Renal Parenchyma + collecting system (pyelonephritis)
  • *Considered complicated if [3]:
    • Male
    • Pregnancy
    • Urolithiasis
    • Structural Abnormalities
    • Catheters/Stents
    • Antibiotic Failure
    • Hospital-associated UTI
    • Immunocompromised
    • Malignancy

Etiology:

• Urine should be sterile from glomerulus to external sphincter in male and bladder neck in females.
• Sterility is due to forward flow, urine acidity, immune system, mucosal barrier.
• Infections are caused by problems in anatomy, structure and function. Also instrumentation.
  • Anatomy:
    • Incompetence in ureterovesical valve –>  vesicoureteral reflux (VUR)
      • 1/3 children under 24 months with febrile UTI
      • Neurogenic bladder
      • Urologic Surgery
    • Congenital urethral valves
    • Bladder diverticulum
  • Structure:
    • Calculi
    • Intrinsic or extrinsic mass effect
      • Example: Men – BPH, urethral stricture
      • Example: Women – Fibroids, pregnant, uterine prolapse or cystocele
    • Function:
      • Dysfunction in bladder emptying
        • Neurogenic bladder
        • Drugs
          • Anticholinergics
          • Antihistamines
          • Antipsychotics
          • Antidepressants
          • Antiparkinsonian
          • Sympathomimetics
          • Muscle Relaxants
        • Instrumentation:
          • Most common cause of nosocomial UTI is Foley catheters
        • Lifestyle:
          • Sexual intercourse, toilet hygiene
            • Introduces bacteria into a woman’s urinary tract
              • Evidence for cranberry as a UTI prophylactic

Created By Ella Barrett-Chan, MSI UBC

Microorganisms:

• Uncomplicated/Complicated: E.Coli (greater than 80%), Staphyloccus Saprophyticus (15%).  Can include other gram negatives (Klebsiella, Proteus) and gram positive (enterococcus, GBS).
• Considerations:
  • Complicated UTI (eg. catheter associated or elderly men) can be polymicrobial.
  • Pseudomonas, Enterococcus faecium, ESBL result in complicated infections.
  • Fluoroquinolone resistance increasing.

• Stable vs Unstable Patient
• UTI vs UTI Mimic (see differential below)
• Simple vs Complicated UTI

History:

• Cystitis: Can include dysuria, urinary frequency, urgency, hematuria
• Pyelonephritis: Can include progression of cystitis to fever, nausea/vomiting, flank pain
• *Include questions to cover differential (see below). Examples:
  • Abnormal vaginal discharge or bleeding? Dyspareunia?
  • Unprotected sexual intercourse?
  • Last Menstrual Period
• Note: Atypical presentations are not uncommon in the elderly

Physical Exam:

• Suprapubic tenderness on abdominal exam
• CVA tenderness common in pyelonephritis
• Vital sign abnormalities in complicated UTI (eg. sepsis)
• *Include exam to cover a differential. Examples:
  • Vaginal/Cervical exam
  • Testicular Exam
  • Abdominal Ultrasound to assess for Abdominal Aortic Aneurysm [see video]

*Differential Diagnosis (UTI mimics) [3]:

• Bacterial Vaginosis
• Sexually transmitted disease (STD)
• Pelvic inflammatory disease (PID)
• Epididymitis/orchitis
• Testicular/ovarian torsion
• Ectopic Pregnancy
• Cholecystitis
• Urolithiasis
• Renal abscess, infarction or thromboembolism
• Appendicitis
• Abdominal Aortic Aneurysm

Urine Dipstick:

• Most commonly used method to diagnose UTI
• Similar sensitivity and specificity to microscopy
  • Leukocyte Esterase – marker of pyuria
    • Diagnosis: Sensitivity 75 – 96%, Specificity 94-98%
    • False Negative with antibiotic therapy, glycosuria, proteinuria
  • Nitrite – marker of bacteria that convert nitrate to nitrite
    • Diagnosis: Sensitivity 35-85%, Specificity 95%
    • False Negative with non-nitrate-reducing bacteria (S. saprophyticus, Pseudomonas, enterococci)
  • Leukocyte Esterase and Nitrite:
    • Diagnosis: Sensitivity 75-90%, Specificity ~ 100%
    • “What if clinically suggestive of UTI, but both Leukocyte Esterase and Nitrite negative?”
      • May still require antibiotics as there are chances for false negatives.
      • Self diagnosis has positive likelihood ratio of 4 (absence of vaginitis symptoms, likelihood ratio of 24)
      • Clinical gestalt is important.
    • “What if asymptomatic but positive leukocyte esterase and/or nitrite?”
      • May not require antibiotics. Patient factors (eg. Pregnancy, Immunocomprimised) are important in decision making.  See UTI Special Considerations section on Asymptomatic Bacteriuria for more details.

Microscopy:

• Optional but perform in recurrent UTI
• Can determine if sample contaminated
• > 10 WBC/mm^3 (non-centrifuged) or > 2-5 WBC/mm^3 (centrifuged) indicative of UTI
• >= 15 bacteria per high power field indicative of UTI
• WBC casts suggestive of Pyelonephritis
• Hematuria helpful in UTI diagnosis
• Note: UTI diagnosis can be made with microscopic bacteriuria and pyuria (+/- hematuria)

Urine culture:

• Not done in cases of uncomplicated UTI (clinical diagnosis)
• Perform in complicated UTI or recent antibiotic use
• Positive when:
  • Suprapubic sample: any bacteria
  • Urethral Catheter: >10^2 cfu/mL, single uropathogen, clinical symptoms
  • Non-catheter: >10^5 cfu/mL
    • >10^2 cfu/mL if known uropathogen in patient with clinical symptoms

Blood Cultures:

• Do not usually alter management
• Usually concordant with urine culture
• Perform in cases of sepsis or septic shock. Can consider in elderly, immunocompromised, urinary tract obstruction

Imaging:

• Not necessary in simple cystitis
• Use if concerned for mimics
• Consider for complicated UTI
• No role for plain radiographs
  • KUB sensitivity 45-59 %/specificity ~77% (for renal pathology)
• Ultrasound
  • Ideal in cases involving pelvic structures
  • Can visualize hydronephrosis
    • Sensitivity ~80%, Specificity 73%
    • See video: renal ultrasound
  • CT is frequently used in complicated UTI
    • Most sensitive test for renal pathology
      • If concerned about severe disease, or UTI mimics, CT is warranted
      • IV contrast if concerned for embolus or thrombus

STD vs UTI

• Can be difficult to distinguish because of overlap in symptoms (eg. dysuria)
  • STD symptoms more gradual in onset and includes vaginal discharge/bleeding, pruritus, dyspareunia. Not typical to have change in urinary frequency/urgency.
  • Assess for STD risk factors including a sexual history
  • Perform vaginal/cervical exam and swabs
  • Can consider treatment of both concurrently
  • Tomas et al. performed an observational cohort study concluding the following:
    • UTI’s are over diagnosed and STD’s are underdiagnosed in the emergency department
    • STD’s can have abnormalities in urinalysis – positive leukocyte esterase or pyuria (defined as more than 5 WBC per HPF)
    • Positive urinalysis does not equal UTI. Can have false positives (eg. STD, asymptomatic bacteruria)
  • Recommendation:
    • STD’s are a common UTI mimic. Take an appropriate history and physical exam/investigations.  Consider treating both.  Use clinical gestalt.  Have appropriate follow-up.

1. Dubbs SB, Sommerkamp SK. Evaluation and management of urinary tract infection in the emergency department. Emergency Medicine Clinics of North America, 2019.

   
   

2. Hooton TM, Gupta K. Acute simple cystitis in women. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2014.

   
   

3. Long B, Koyfman A. The emergency department diagnosis and management of urinary tract infection. Emerg Med Clin North Am. 2018;36:685-710.

   
   

4. Tomas ME, Getman D, Donskey CJ, Hecker MT. Overdiagnosis of urinary tract infection and underdiagnosis of sexually transmitted infection in adult women presenting to an emergency department.  Journal of Clinical Microbiology. 2015 Aug;53:2686–92.

   
   

5. Walker EB, Barney DP, Mickelsen JN, Walton RJ, Mickelsen RA. Cranberry concentrate: UTI prophylaxis. Journal of Family Practice [Internet]. 1997Aug1;45(2).

   
   

1. App – Spectrum Antimicrobials 

   
   

2. Video: Ultrasound of Abdominal Aortic Aneurysm (AAA)

   
   

3. Video: Renal Ultrasound – Hydronephrosis