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CDHB

Acute Pyelonephritis

• A syndrome of fever (>37.8°C) ± rigors, loin pain or tenderness together with infected urine. If no fever or pyuria, reconsider the diagnosis.
• Lower urinary tract symptoms may be absent.
• Symptoms may be unilateral or bilateral.
• Patients with severe acute pyelonephritis (toxic, requiring IV fluids or parenteral analgesia) require hospitalization.
• 10-15% will have a bacteraemia.

Causes

• Acute pyelonephritis may occur in a structurally normal urinary tract (uncomplicated) or as a complication of some underlying urinary tract structural or functional disorder (complicated).

Investigations

• The clinical features are usually clear-cut, but the diagnosis must be confirmed bacteriologically. In a patient with acute pyelonephritis approximately 80% will have a colony count >100 x 10⁶ colony forming units per L (cfu/L), 10-15% will have 10-100 x 10⁶ cfu/L and the remainder will have small numbers of uropathogens on culture of a midstream urine specimen. Significant pyuria (>10x10⁶ white cells/L) will invariably be present.
• Rectal and vaginal examinations should be done only if clinically indicated.
• CBC + diff.
• Na, K, and creatinine.
• Blood cultures. These are not indicated in uncomplicated acute pyelonephritis. Blood cultures should be taken if there is: doubt over the diagnosis; evidence of sepsis (i.e., satisfies criteria for SIRS); renal failure; or a prosthetic device is present.
• Patients with acute pyelonephritis who follow an atypical course, e.g., fever or severe loin pain >48-72 hours, (?obstruction, kidney stone) should have an ultrasound examination of the urinary tract. A CT urogram is the best test if a urinary stone is suspected.
• A cystoscopy may very occasionally be indicated.

Management

• If the patient is dehydrated and/or vomiting, give IV sodium chloride 0.9%.
• Parenteral antimicrobial therapy usually consists of a single intravenous dose of antibiotic (e.g., gentamicin). The choices of parenteral agents are gentamicin - initial dose 3 mg/kg, ciprofloxacin 200 mg q12h, ceftriaxone 2 g q24h.
• Oral therapy (e.g., ciprofloxacin 500 mg BD - see the Pink Book for other options, including for pregnant patients or those in severe renal failure) starts on the second day of treatment and is given for 5 days.

Notes:

• The aminoglycosides and quinolones are the drugs of choice.
• Check local sensitivity patterns for trimethoprim.
• Ampicillin or amoxicillin should not be used, at least until the antibacterial sensitivity profile is known, as about 50% of E.coli locally are now resistant to these antibiotics. Amoxicillin/ clavulanate should also be avoided because of its slow clinical response, low cure rate and high incidence of side effects.

The urine should be recultured 10-14 days after completion of therapy.

Topic Code: 1493