• Clinical science
  • Physician

Pyelonephritis

Summary

Pyelonephritis is an infection of the renal pelvis and parenchyma that is usually associated with an ascending bacterial infection of the bladder. It occurs more commonly in females and risk factors include pregnancy and urinary tract obstruction. Patients typically present with flank pain, costovertebral angle tenderness, fever, and other features of cystitis (e.g., dysuria, frequency). Urinalysis reveals leukocyturia and bacteriuria. Urine cultures should be taken in all patients before initiating treatment to identify the pathogen and possible antibiotic resistance. Treatment depends on the drug sensitivities of the offending pathogen and the patient's clinical profile (e.g., possible comorbidities). Early empiric antibiotic treatment is essential to avoid renal complications and urosepsis.

Etiology

References:[1][2]

Clinical features

  • High fever, chills
  • Flank pain, costovertebral angle tenderness (usually unilateral, may be bilateral)
  • Dysuria as well as other symptoms of cystitis (e.g., frequency, urgency)
  • Weakness, nausea, vomiting (diarrhea may also be present)
  • Possible abdominal or pelvic pain

References:[3]

Subtypes and variants

Chronic pyelonephritis [4][5]

Diagnostics

Laboratory tests

  • Urinalysis
  • Blood
    • ↑ Inflammatory markers
    • Normal or ↑ renal function parameters
  • Urine culture and blood culture

Urine and blood cultures should be ordered before initiating empiric antibiotic therapy!

Imaging

Generally not necessary for diagnosis

References:[3]

Pathology

Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

While uncomplicated pyelonephritis usually only requires outpatient treatment, complicated pyelonephritis requires hospitalization. Pyelonephritis is considered complicated if any of the following is present:

  • Urinary tract abnormalities (e.g., obstruction, indwelling catheter)
  • Recent surgery to the urinary tract
  • Renal impairment
  • Immunosuppression and/or severe comorbidities
  • Sepsis
  • High-risk patient despite uncomplicated clinical picture (e.g., elderly)

Uncomplicated pyelonephritis

  • Outpatient treatment
  • Encourage the patient to drink adequate amounts of fluids.
  • Oral treatment is often preceded by a single dose of ceftriaxone or gentamicin.
  • First-line: oral fluoroquinolones (e.g., ciprofloxacin for 7 days)
  • Second-line: oral trimethoprim-sulfamethoxazole for 14 days
  • If there is no response within 48 hours, then check urine culture results and change treatment accordingly.
  • Repeat urine culture 2–4 days after completion of the antibiotic course.

Complicated pyelonephritis

Empiric antibiotic therapy should be initiated immediately. After urine and blood culture results are available, the antibiotic regimen can be adjusted.

In contrast to antibiotic treatment with most cephalosporins, empiric therapy with ciprofloxacin also covers infections with enterococci.

Empiric antibiotic therapy for complicated pyelonephritis [6][7][8]

Hemodynamically stable patients without risk factors for MDR gram-negative bacterial infection

Critically ill patients,
patients with a urinary tract obstruction,

and/or patients with risk factor(s) for MDR gram-negative bacterial infection

References:[1][3][2]

Acute management checklist

Uncomplicated pyelonephritis [11][6][7][8]

Complicated pyelonephritis [6][7][8]

Complications

References:[2]

We list the most important complications. The selection is not exhaustive.

Special patient groups

Pyelonephritis in pregnancy [3]

All asymptomatic cases of bacteriuria during pregnancy must be treated to prevent the development of pyelonephritis!

Do not use fluoroquinolones or trimethoprim/sulfamethoxazole in pregnant women!

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last updated 03/27/2020
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