Urinary Tract Infection (UTI) in Children: Presentation, Investigation & Treatment

Urinary Tract Infection (UTI)

UTI in children requires prompt investigation, since progressive renal failure and hypertension may occur insidiously. 35% have proven vesico-ureteric reflux: early treatment may help to prevent renal failure.

UTI may present in a variable and non-specific fashion. Consider and exclude UTI as part of the initial approach to any ill child presenting to the ED.

Presentations

Older children typically present with lower abdominal pain, dysuria, frequency, offensive urine, haematuria or fever.

However, dysuria and frequency do not always reflect UTI.

Children <3 years old often present unwell with fever and irritability, but no specific signs.

Infants may present with poor feeding, vomiting, and failure to thrive.

Examination

Always check the BP and feel for loin tenderness (pyelonephritis) and abdominal masses (polycystic kidneys).

Investigation

Obtain a clean catch specimen of urine for urinalysis, microscopy, culture and sensitivity. This can prove to be quite difficult, depending upon the age of the child.

Try one of the following approaches:

Neonates and infants

• Clean the perineum with sterile water, then tap with 2 fingers just above the symphysis pubis (ideally 1hr post-feed) and catch the urine which is forthcoming, trying to avoid the first few millilitres.
• Clean the perineum as above and use a urine collection pad according to the manufacturer’s instructions.
• Suprapubic aspiration is useful if the baby is seriously ill. Clean skin with antiseptic solution, then using sterile gloves and an aseptic technique, insert a 21G needle in the midline 2.5cm above the pubic crest and aspirate urine.

Toddlers and older children

• Co-operation will enable an MSU to be obtained (in the male, gently retract the foreskin (if possible) and clean the glans first; in the female, separate the labia and clean the perineum front to back, first).
• If the child is uncooperative, try a urine collection pad or bag.

Dipstick urinalysis at the bedside will reveal the presence of blood, protein, sugar, bilirubin, ketones or nitrites.

A positive nitrite test is accepted as good evidence of UTI.

Urine pH is not usually helpful, for although pH <4.6 or >8.0 may reflect infection, it may also be due to various acid-base disorders.

Urinalysis may be normal, despite bacteriuria.

Urine microscopy allows a search for pyuria and bacteriuria (highly suggestive of UTI) and an accurate assessment of other constituents (see Table 15.7).

Perform FBC, U&E, blood glucose, and blood cultures if septicaemic, loin pain or ↑ T°.

Treatment

• Children with suspected pyelonephritis or who appear toxic: resuscitate as necessary with IV fluids and refer for admission and IV antibiotics (eg cefotaxime).
• Infection with beta lactamase producing E. coli is said to be increasing, and some recommend at least one dose of gentamicin, pending sensitivities.
• Give antibiotics for 10 days.
• Symptomatic children with abnormal urinalysis (proteinuria or haematuria): start a 3-day course of antibiotics PO (trimethoprim or cefalexin—dose according to age, refer to BNFC).
• Encourage plenty of oral fluids and complete voiding of urine.
• Offer advice to the child and parents (eg avoid tight underwear, use toilet paper wiping from front to back).
• Organize paediatric follow-up to receive results of MSU and to arrange subsequent investigations: this may include U&E, blood glucose, ultrasound scan (USS) and a variety of other tests (eg isotope renography and micturating cysto-urethrography), according to local policy.
• Recurrent UTIs with anogenital signs may be due to sexual abuse.

Urine Microscopy Findings and Their Significance

Finding	Significance
Red cells	Normally <3/mm³
White cells	Normally <3/mm³
Epithelial cells	Present normally: shed from urinary epithelium
Bacteria or fungi	Always abnormal, reflecting infection or specimen contamination
Casts	Hyaline casts—comprise Tamm–Horsfall protein: may be normal, but ↑ in fever, exercise, heart failure, after diuretics. Fine granular casts—may be present normally, eg after exercise. Coarse granular casts—abnormal, seen in various renal disorders. Red cell casts—imply glomerular disease and glomerular bleeding. White cell casts—occur in glomerulonephritis and pyelonephritis. Epithelial casts—usually reflect tubular damage.
Crystals	Phosphate, urate, and oxalate crystals may not be pathological, but are also seen in Proteus UTI and hyperuricaemia.

See the NICE Guidance on UTI in Children.