Most common bacterial infection in children.
1 – 2 % of children.
Dramatic increases over recent decades – likely better and earlier detection with testing and dipsticks.
Most common in boys under 12 months, then more common in girls.
UTIs in children are more likely to be associated with an underlying anatomic abnormality (cf. adults).
Pathophysiology
Similar to adults – most common by far is ascent of bacterial organisms via urethra (perineal or preputial source) into bladder.
Bacteria in the bladder can then go on to form symptomatic infection if allowed to replicate.
Risk factors:
E.coli by far the most common causative organism ( > 80 %) followed by proteus, klebsiella, pseudomonas, Enterobacter.
Traditionally a large proportion of children (> 40 %) referred for investigation were found to have underlying urinary tract abnormalities, but that number is reducing with more children with mild and early UTIs found and being investigated.
Many abnormalities found may be of little clinical significance (low grade reflux, incomplete duplex etc).
Classification
Presentation
Neonates / infants – fever, vomiting, lethargy, irritability
Infants / young children – poor appetite, failure to thrive, lethargy, vomiting, diarrhoea
Toilet-trained children – cystitis symptoms or flank pain, fever
Work-up and investigation:
History:
- Antenatal history and scans
- Symptomatology
- Previous UTIs? (which organisms, treatment, symptoms)
- Medical history / immunosuppression
- Known urological issues
- Bladder or bowel dysfunction
- Constipation / bowels
- Family history of reflux
- Surgical history / prior procedures
Examination:
- Obs
- Fevers
- Suprapubic or flank tenderness
- Palpable bladder or constipation
- Genital exam – foreskin, orchitis, hypospadias, labial adhesions
- Lymph node exam
- Stigmata of spina bifida
- Exclude other causes of febrile illness – e.g. meningitis
Urine culture:
- Preferably before antibiotics. Can be challenging.
- Plastic bag around genitals – pragmatic with high contamination rates
- Clean catch urine – caregiver holds infant and waits for void – most useful
- Urethral catheter – uncomfortable
- Suprapubic aspirate – invasive, should be done under USS, but no contamination
- Toilet trained kids may be able to give adequate mid stream urine with genital cleansing prior
- Dipsticks fairly sensitive – leukocyte esterase and nitrites combined high PPV
- Culture should be performed – > 105 cfu / mL reasonable cut off to define bacterial infection
- Any bacteria cultured on suprapubic tab should be considered significant
Bloods including renal function and CRP.
Imaging:
- Ultrasound
- Advised in all cases of febrile UTI within 24 hours
- Abnormality in 15 %
- May find hydro (VUR, PUV, PUJO), stones, XGP, abscess, poor emptying
If ultrasound is normal, is further imaging needed?
- MCUG
- Optimal method for detecting reflux – important to find with febrile UTIs given potential for scarring
- However investigating every child with a UTI with MCUG would give a lot of invasive negative tests, and potentially pick up a lot of low grade VUR
- Indicated for abnormal ultrasound, recurrent UTIs or ‘atypical’ UTI – including family history VUR, pyelonephritis, first 6 months of life, failure to respond within 48 hours, raised creatinine, poor urinary stream
- DMSA or MAG3
- DMSA for renal scarring
- DMSA may show abnormalities in acute pyelonephritis
- MAG3 if concerns for obstruction
EAU:
Management
Acute UTI – RCH guidelines
- If < 3 months, or seriously unwell – IV antibiotics
- Cefalexin oral 33 mg/kg oral BD
- Benzylpenicillin + gentamicin for IV
- Total 3 – 10 days depending on severity
- IV fluids as needed
- Check renal function, ultrasound in seriously unwell children
- Consider lumbar puncture and blood cultures if little improvement
Longer term management
- Treat any underlying identifiable causes
- Voiding dysfunction and bowel dysfunction are crucial and must be proactively managed
- Consider circumcision in boys with recurrent UTIs
- Cranberry and probiotic yoghurts probably not harmful
- Increase fluid intake and don’t forget to look for and treat bladder and bowel dysfunction