ACUTE PYELONEPHRITIS

Upper urinary tract infection involving one or both kidneys (but not usually involving the glomeruli)

Cause

  • Bacterial infection, e.g. Escherichia coli, usually due to ascending infection (faecal-perineal-urethral progression of bacteria)

Risk factors

  • Bladder outlet obstruction
  • Malformations of urinary tract
  • Pregnancy
  • HIV, old age, diabetes

Clinical features

  • Loin pain, tenderness in one or both kidney areas (renal angle)
  • Fever, rigors (generalised body tremors)
  • Vomiting
  • If associated cystitis: dysuria, urgency, frequency
  • Diarrhoea and convulsions (common in children)
  • In infants and elderly: may simply present as fever and poor feeding/disorientation without other signs

Differential diagnosis

  • Appendicitis
  • Infection of the fallopian tubes (salpingitis)
  • Infection of the gall bladder (cholecystitis)

Investigations

  • Urine: Microscopy for pus cells and organisms, C&S of mid-stream urine
    • Specimen should reach the lab within 2 hours of collection or be refrigerated at 4°C for not >24 hours
      • Blood: Full count, C&S, urea, electrolytes
      • Ultrasound kidneys/prostate

Management

  • Ensure adequate intake of fluid (oral or IV) to irrigate bladder and dilute bacterial concentrations
  • Give paracetamol 1 g every 6-8 hours for pain and fever

If outpatient (only adults):

  • Ciprofloxacin 500 mg every 12 hours for 10-14 days (only adults)

In severe cases, all children or if no response to above in 48 hours:

  • Ceftriaxone 1 g IV once a day
    Child: 50-80 mg/kg IV once a day

Following initial response to parenteral therapy

  • Consider changing to:
    • Ciprofloxacin 750 mg every 12 hours to complete 10 days (adults only)
    • Or cefixime 200 mg every 12 hours to complete 10 days of treatment
      Child: 16 mg/kg the first day then 8 mg/kg to complete 10 days

Alternative regimen

  • Gentamicin 5-7 mg/kg IV in one or divided doses with or without ampicillin 2 g IV every 6 hours
    Child : gentamicin 2.5 mg/kg every 8 hours (or 7.5 mg/kg once daily on outpatient basis) with or
    without ampicillin 25 mg/kg every 6 hours
  • Consider referral if there is no response in 72 hours and for children with recurrent infections
    (to exclude urinary tract malformations)

Prevention

  • Ensure perianal hygiene
  • Ensure regular complete emptying of the bladder and/or double voiding (additional attempt to empty bladder after initial urine flow ceases)