UTI (Urinary Tract Infection)


Introduction


Classification

On basis of location

  1. Lower UTI
    • Cystitis
    • Prostatitis
    • Urethritis
  2. Upper UTI (Pyelonephritis)

On basis of complications:

  • Uncomplicated UTI
    • Normal urinary tract
    • Normal urinary function
  • Complicated UTI
    • ↓ Renal function
    • Abnormal urinary tract

Aetiology

Causative organisms

KEEPS
  • Klebsiella
  • E. coli (M/C, as predominant periurethral flora)
  • Enterococcus, Enterobacteriaceae
  • Proteus, Pseudomonas (commonly following obstruction/instrumentation)
  • Staphylococcus saprophyticus, Serratia

Risk factors: Recurrent UTI (30-50% children)

Usually occurs within 3 months of the first episode
  • Female sex
  • Age < 6 months or elderly
  • Obstructive uropathy (stagnant urine)
  • Severe vesicoureteric reflux (VUR) (M/C cause of recurrent UTI in children)
  • Habitual postponement of voiding (voiding dysfunction)
  • Constipation
  • Repeated catheterization, e.g. for neurogenic bladder
  • Immunosuppression:
    • Malnutrition
    • Immunosuppressive therapy

Clinical features

Difficult to distinguish between infection localized to the bladder (cystitis) and upper tracts (pyelonephritis)

Clinical triad:

  1. Nausea/vomiting
  2. Fever
  3. Flank pain (Costovertebral Angle Tenderness)

Clinical types:

  • Simple UTI
    • Low-grade fever
    • Dysuria, frequency and urgency
    • Absence of symptoms of complicated UTI
  • Complicated UTI
    • High fever (>39°C)
    • Systemic toxicity
    • Persistent vomiting
    • Dehydration
    • Renal angle tenderness
    • ↑ creatinine 

Paediatric age-group:

  • Neonates:
    • Sepsis with fever
    • Vomiting
    • Diarrhea
    • Jaundice
    • Poor weight gain
    • Lethargy
  • Older infant:
    • Unexplained fever
    • Frequent micturition
    • Occasional convulsions
  • Urinary obstruction:
    • Crying or straining during voiding
    • Dribbling, weak or abnormal urine stream
    • Palpable bladder
upper-urinary-tract-infection-uuti
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Complications

luti-complications
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Diagnosis

Urine examination

  • Sample:
    • Voiding
    • Children below 2 yr:
      • Suprapubic bladder aspiration or Urethral catheterization
  • Significant bacteriuria
    • Colony count of > 105/ml of a single species in a clean catch sample
  • Asymptomatic bacteriuria
    • Significant bacteriuria in absence of symptoms

Imaging:

Following treatment of the first episode of UTI, plans are made for evaluation of the urinary tract:
  • Renal ultrasonography
    • Detects hydronephrosis or anomalies of the urinary bladder
    • Can be performed even during therapy for UTI
  • Micturating cystourethrogram (MCU)
    • Diagnosis and grading of VUR
    • Defines urethral and bladder anatomy
    • Can be performed 2-4 weeks after treatment of the UTI
  • Dimercaptosuccinic acid (DMSA) scintigraphy
    • Detects cortical scars (regions of decreased uptake with loss of renal contours or presence of cortical thinning with decreased volume)

Management

Infants < 3 months of age & complicated UTI

  1. Parental antibiotics (48-72 hrs):
    • Cephalosporins:
      • Ceftriaxone 75-100 mg/kg/day, in 1-2 divided doses IV
      • Cefotaxime 100-150 mg/kg/day, in 2-3 divided doses IV
    • Aminoglycoside:
      • Amikacin 10-15 mg/kg/day, single dose IV or IM
      • Gentamicin 5-6 mg/kg/day, single dose IV or IM
      • Co-amoxiclav 30-35 mg/kg/day of amoxicillin, in 2 divided doses IV
  2. Oral antibiotics (10-14 days):
    • Cefixime 8-10 mg/kg/day, in 2 divided doses
    • Co-amoxiclav 30-35 mg/kg/day of amoxicillin, in 2 divided doses
    • Ciprofloxacin 10-20 mg/kg/day, in 2 divided doses
    • Ofloxacin 15-20 mg/kg/day, in 2 divided doses
    • Cephalexin 50-70 mg/kg/day, in 2-3 divided doses

Older children & simple UTI

  • Oral antibiotics (7-10 days)

Adolescents with cystitis:

  • Oral antibiotics (72 hr)

Prophylactic antibiotics (until imaging results are obtained)

  • Cotrimoxazole
  • Nitrofurantoin
  • Cephalexin
  • Cefadroxil

Summary

 


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