What is the initial workup and treatment for a patient suspected of having pyelonephritis?

Workup and Treatment for Pyelonephritis

The initial workup for suspected pyelonephritis should include urinalysis, urine culture, and assessment for sepsis, followed by empiric antibiotic therapy with either oral fluoroquinolones (in areas with <10% resistance) or an initial parenteral dose of ceftriaxone followed by oral therapy (in areas with >10% resistance). 1, 2

Diagnostic Workup

Clinical Assessment

• Evaluate for classic symptoms:
  • Flank pain (nearly universal - absence should raise suspicion of alternative diagnosis) 2
  • Fever (may be absent early in illness)
  • Dysuria, frequency, urgency
  • Nausea/vomiting
  • Signs of sepsis (tachycardia, hypotension, altered mental status)

Laboratory Tests

• Urinalysis: Confirms diagnosis in patients with compatible history and physical exam 2
  • Look for pyuria, bacteriuria, leukocyte esterase, nitrites
• Urine culture with antimicrobial susceptibility testing: Obtain in ALL patients before starting antibiotics 1, 2
• Consider additional tests in complicated cases:
  • Complete blood count
  • Basic metabolic panel
  • Blood cultures (if sepsis suspected)

Imaging

• Not necessary for uncomplicated cases with typical presentation 3
• Indications for imaging (usually contrast-enhanced CT):
  • No improvement in symptoms after 48-72 hours of appropriate therapy
  • Recurrence of symptoms after initial improvement
  • Suspected complications (abscess, obstruction)
  • History suggesting anatomic abnormality
  • Immunocompromised host

Treatment Approach

Outpatient vs. Inpatient Management

• Outpatient treatment appropriate for most patients who:

  • Can tolerate oral therapy
  • Have no signs of sepsis
  • Have no complicating factors 2, 3

• Inpatient treatment recommended for:

  • Severe illness/sepsis
  • Inability to tolerate oral medications
  • Suspected complications
  • Pregnancy (especially 2nd or 3rd trimester) 1
  • Immunocompromised patients

Empiric Antibiotic Therapy

Outpatient Treatment

• In communities with fluoroquinolone resistance <10%:

  • Ciprofloxacin 500 mg PO twice daily 1, 4, 2
  • Levofloxacin 750 mg PO once daily 1

• In communities with fluoroquinolone resistance >10%:

  • Initial dose of ceftriaxone 1-2 g IV/IM, THEN
  • Oral fluoroquinolone therapy as above 1, 2

• Alternative for outpatients when fluoroquinolones contraindicated:

  • Initial dose of gentamicin 5 mg/kg IV/IM, THEN
  • Appropriate oral therapy based on local susceptibility patterns 1

Inpatient Treatment

• IV antibiotic options:

  • Ceftriaxone 1-2 g IV once daily 1
  • Cefepime 1-2 g IV twice daily 1
  • Piperacillin/tazobactam 2.5-4.5 g IV three times daily 1
  • Ciprofloxacin 400 mg IV twice daily 1, 4
  • Levofloxacin 750 mg IV once daily 1

• For suspected extended-spectrum beta-lactamase (ESBL) producing organisms:

  • Consider broader coverage with carbapenems 3

Special Populations

Renal Impairment

• Ciprofloxacin dosing adjustments 4:
  • CrCl 30-50 mL/min: 250-500 mg q12h
  • CrCl 5-29 mL/min: 250-500 mg q18h
  • Hemodialysis/peritoneal dialysis: 250-500 mg q24h (after dialysis)

Pregnant Women

• Require inpatient management with parenteral therapy initially 1
• Follow-up with urine culture 1-2 weeks after therapy completion
• Monthly urine cultures for remainder of pregnancy due to high recurrence risk (20-30%) 1

Pediatric Patients

• Intravenous therapy: 6-10 mg/kg (max 400 mg) every 8 hours 4
• Oral therapy: 10-20 mg/kg (max 750 mg) every 12 hours 4
• Duration: 10-21 days 4

Duration of Therapy

• 10-14 days total treatment is recommended 1, 2, 3
• Some evidence supports 7-day course of ciprofloxacin in uncomplicated cases 5
• Transition to oral therapy when clinically improved 1

Common Pitfalls to Avoid

• Delaying antibiotic administration beyond one hour after diagnosis 1
• Not obtaining cultures before starting antibiotics 1
• Using fluoroquinolones empirically in areas with high resistance (>10%) without an initial parenteral dose 1, 6
• Using oral β-lactams as first-line empiric therapy (high resistance rates) 1, 2
• Using trimethoprim-sulfamethoxazole empirically without knowing susceptibility 1, 2
• Not adjusting therapy based on culture results 1
• Using unnecessarily broad-spectrum antibiotics for uncomplicated cases 1, 6
• Failing to recognize and promptly address urinary tract obstruction (requires urgent decompression) 1, 3