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Basics

[Section Outline]

Author:

Paul A.Szucs

BarnetEskin


Description!!navigator!!

Etiology!!navigator!!

Diagnosis

[Section Outline]

Signs and Symptoms!!navigator!!

Essential Workup!!navigator!!

Diagnostic Tests & Interpretation!!navigator!!

Lab

  • Rapid urine screen:
    • Dipstick (leukocyte esterase + nitrite) most effective when urine contains 105 CFU/mL
    • Lab specimen unnecessary if pyuria and bacteriuria confirmed by dipstick
    • Leukocyte esterase: Positive likelihood ratio (LR+) 5, negative likelihood ratio (LR) 0.3
    • Nitrite: LR+ 30, LR0.5
  • Urinalysis/microscopy:
    • Obtain if rapid urine screen is unavailable or negative in patients with presumed UTI
    • 10 WBC/mm3 in clean catch midstream urine indicates infection
    • Bacteria detected in unspun urine indicates >105 CFU/mL (LR+ 20, LR0.1)
  • Indications for urine culture:
    • Complicated UTIs
    • Negative rapid urine screen or microscopy in patients with presumed UTI
    • Persistent signs and symptoms after 2-3 d of treatment
    • Recurrence (relapse vs. reinfection)
    • Recently hospitalized patients
    • Nosocomial infections
    • Pyelonephritis
  • Urine color:
    • White/cloudy/murky:
      • Crystals, pyuria
    • Red/pink:
      • Beets, blackberries, rhubarb
      • Chlorpromazine, phenazopyridine, phenolphthalein, rifampin, senna, thioridazine
      • Blood
    • Brown:
    • Orange:
    • Blue/green:
      • Asparagus, food dyes, vitamins B
      • Amitriptyline, cimetidine, indomethacin, promethazine, propofol, triamterene
      • Familial benign hypercalcemia
    • Purple (rare):
      • Porphyria
Geriatric Considerations
  • Asymptomatic bacteriuria (including positive cultures) occurs in 20% of women >65 yr, 50% of women >80 yr and generally should not be treated
  • Treating symptomatic geriatric patients for a shorter duration than the typical 7-10 d appears to be effective with no increased risk of recurrent or persistent bacteriuria
  • The FDA has reported that fluoroquinolones may cause serious side effects, including but not limited to, CNS side effects and tendon ruptures

Imaging

  • Indicated for complicated upper tract disease (see Pyelonephritis)
  • Helical CT, renal US, or IV pyelogram if concomitant stone or obstruction suspected

Diagnostic Procedures/Surgery

Patients with significant hematuria, recurrent UTI with same uropathogen, or symptoms of obstruction need urologic evaluation to identify structural or functional abnormality

Differential Diagnosis!!navigator!!

Treatment

[Section Outline]

Initial Stabilization/Therapy!!navigator!!

Urosepsis/septic shock:

ED Treatment/Procedures!!navigator!!

Stable Patients

  • Considerations for antibiotic selection include: Clinical efficacy, side-effects, resistance rates, cost, drug availability
  • Individualize treatment regimens based on patient characteristics (allergy, tolerability, cost, compliance) and local community resistance prevalence
  • Optimal antibiotic treatment duration is similar for any adult woman regardless of age (3-7 d)
  • For uncomplicated UTIs in women for most antibiotics, 3 d of therapy:
    • More effective than single dose
    • Clinically as effective as 5-10 d course with fewer side effects
    • Beta-lactams should be prescribed for 7 d
  • Resistance varies by community and changes over time:
    • In North America, 40-50% of E. coli are resistant to ampicillin; 3-17% to fluoroquinolones
    • Resistance to trimethoprim-sulfamethoxazole (TMP/SMX) is increasing (up to 30%)
    • Nitrofurantoin: In some studies, resistance is less than for other more widely used antibiotics
    • Culture resistance may not correlate with clinical effect because urine antibiotic concentrations are much higher than those used in lab testing
    • Avoid antibiotic if community resistance prevalence >20%
  • Cranberry juice or tablets/products:
    • Evidence suggests ineffective for treatment
    • Prevents specific E. coli from adhering to uroepithelial cells but probably does not lower UTI recurrence rate in women with h/o recurrent UTIs
  • Historic treatment of upper tract disease - rule of 2s:
    • 2 L of IV crystalloid
    • 2 tablets of oxycodone/acetaminophen
    • 1 g of ceftriaxone or 2 mg/kg of gentamicin
    • If fever drops by 2°C and patient can retain 2 glasses of water
    • Discharge with fluoroquinolone for 2 wk
    • Follow up in 2 d
  • Antibiotics of choice:
    • Nitrofurantoin:
      • Avoid if creatinine clearance < 30 mL/min
      • Inadequate if early pyelonephritis is suspected
    • TMP/SMX
    • Fosfomycin:
      • Inadequate if early pyelonephritis is suspected
    • β-lactams are second-line agents:
      • Less effective than TMP/SMX and fluoroquinolones
    • Oral cephalosporins are reasonable alternatives in specific circumstances:
      • Require 7-d treatment regimens
    • Ampicillin or amoxicillin should not be used for empiric treatment due to high-resistance rates
    • Amoxicillin-clavulanate not as effective as ciprofloxacin probably due to failure to eradicate vaginal E. coli
    • Fluoroquinolones:
      • Alternative treatment for women
      • Risks outweigh benefits for uncomplicated UTI
      • Tendon ruptures; CNS side effects
      • All quinolones equally effective (95% susceptibility rates) but side effects vary
      • High prevalence of antimicrobial resistance
      • Live in areas with unknown or >20% resistance to Nitrofurantoin and /or TMP/SMX
    • Diabetic women have increased risk of bacteriuria with Klebsiella spp.
    • Treat dysuria with phenazopyridine
    • Treat pain with appropriate analgesics
Pregnancy Prophylaxis
  • Treat asymptomatic bacteriuria in pregnancy with 4-7 d course of antibiotics:
    • Nitrofurantoin:
      • May cause birth defects if used in first trimester
      • Contraindicated in G6PD-deficiency
    • TMP/SMX:
      • SMX should be avoided late in pregnancy as kernicterus can result
      • TMP should be avoided in first trimester (folic acid antagonist; possible birth defects)
    • Fosfomycin is safe and effective
    • Amoxicillin not recommended due to high resistance rates
    • Quinolones should be avoided:
      • CNS reactions
      • Blood dyscrasias
      • Effects on collagen formation

Medication!!navigator!!

Follow-Up

[Section Outline]

Disposition!!navigator!!

Admission Criteria

  • Inability to comply with oral therapy
  • Toxic appearing, unstable vital signs
  • Pyelonephritis:
    • Intractable symptoms
    • Extremes of age
    • Immunosuppression
    • Urinary obstruction
    • Consider if coexisting urolithiasis
    • Significant comorbid disease
    • Outpatient treatment failure
    • Late in pregnancy

Discharge Criteria

  • Well appearing, normal vital signs
  • Can comply with oral therapy
  • No significant comorbid disease
  • Adequate follow-up (48-72 hr) as needed
  • Healthy patients with uncomplicated pyelonephritis who respond to treatment in the ED according to rule of 2s
  • Pyelonephritis in early pregnancy with good follow-up may be treated as outpatients

Issues for Referral

Recurrent UTIs require workup for underlying pathology

Follow-up Recommendations!!navigator!!

Follow-up for UTIs should start with primary care physician

Pearls and Pitfalls

  • For women who have more than 2 episodes of acute cystitis in 6 mo or 3 episodes in 1 yr, consider long-term (6-12 mo) prophylactic antibiotics or postcoital prophylaxis
  • Pregnant women should be screened and treated for asymptomatic bacteriuria (ASB) because 20-40% of women with ASB progress to pyelonephritis
  • ASB in pregnant women associated with increased risk of preterm birth, low birth weight, and perinatal mortality
  • Treat ASB in renal transplant recipients, patients who have recently undergone a urologic procedure, and neutropenic patients
  • Risk factors for acute cystitis in men: Increased age, uncircumcised, HIV infection (low CD4 counts), anatomic abnormalities (BPH or urethral strictures), and sexual activity (especially insertive anal intercourse)
  • 25% of male GU complaints are attributable to prostatitis. TMP/SMX or fluoroquinolones are first-line treatment
  • In patients with indwelling catheters, pyuria is less strongly correlated with UTI than in patients without catheters

Additional Reading

See Also (Topic, Algorithm, Electronic Media Element)

Codes

ICD9

ICD10

SNOMED