Cystitis or pyelonephritis

[Pediatrics 2011; 128:595-610]

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- 5% of children presenting with fever have urinary tract infection (UTI); more common in girls and uncircumcised boys.

- UTI in children <1 month most often due to hematogenous seeding rather than ascending infection. Complete septic work-up recommended.

Diagnosis:

- Blood culture recommended if:

• febrile (NB: < 2 months old may not be febrile)

• signs and symptoms of pyelonephritis

• immunocompromised.

- Preverbal children with fever and no obvious source for infection should be investigated for possible UTI.

- Urine specimen - submit for urinalysis and urine culture:

• Bag urine specimens are usually contaminated (false positive rate >85%) and cannot be relied upon to diagnose UTI. Only useful if negative as excludes UTI. If positive, must be confirmed with a proper specimen BEFORE antibiotics.

• In/out catheter specimens are preferred for the diagnosis of UTI in young children. Although they have better specificity than bag specimens, contamination may also occur. Organism(s), colony count and clinical picture must all be considered when interpreting results.

• For children who are not toilet trained, collect urine by suprapubic, in/out catheter, or properly collected midstream urine (MSU).

• For children who are toilet trained, collect urine by properly collected MSU or in/out catheter.

• For older children, collect MSU ideally no sooner than 2 hours afer last voiding.

  • < 3 years old - send urine specimen for microscopic urinalysis (WBC/bacteria) and urine culture.

  • > 3 years of age - send urine specimen for macroscopic +/- microscopic urinalysis and urine culture.

NB: Pyuria alone does not confirm a diagnosis of UTI.

- ≥10⁸ cfu/L - significant colony count indicative of urinary tract infection WITH signs & symptoms. NB: some laboratories only report a maximum colony count of ≥10⁷ cfu/L.

- ≥10⁷ cfu/L – may be significant colony count in in/out catheter specimens and in infants/children with definite UTI symptoms and single uropathogen.

- ≥10⁶ cfu/L – usually a contaminated urine unless from a suprapubic aspirate.

- 10⁵ cful/L - significant colony count with suprapubic aspirate or cystoscopy.

- ≥ 2 mixed organisms – probable contamination. May be significant in children with complex genitourinary abnormality.

- Indications for ultrasound of kidneys and bladder:

• septicemia

• children < 2 years of age after first febrile UTI

• UTI due to organism other than E. coli

• delayed (> 48h) response to appropriate therapy

• abdominal or bladder mass

• abnormal urinary stream

• renal function impairment

• recurrent febrile UTI.

- VCUG no longer routinely recommended after first febrile UTI, but only if US shows hydronephrosis, renal dysplasia, scarring or findings of high grade vesicoureteral reflux (VUR) or abnormal urine stream/obstructive uropathy, or if there is a recurrence of a febrile UTI in children less than 2 years of age.

- DMSA scan may be used acutely to confirm pyelonephritis, or at 6-12 months to assess for renal scarring. Not optimal for diagnosing VUR.

Recurrent UTI:

- Prophylaxis with antibiotics NOT recommended in most cases as the number needed to treat to prevent one UTI is very high and prophylaxis increases the risk of resistant infections.

- Parents should be instructed to seek prompt (within 48h) medical evaluation of their child for future febrile illnesses to ensure detection and prompt treatment of recurrrent infection.

Treatment:

- Amoxicillin is NOT recommended empirically due to unacceptably high E. coli resistance.

- Significant resistance to TMP/SMX; knowledge of local susceptibility patterns and confirmation of susceptibility by culture is recommended.