Childhood Urinary Tract Infection (UTI)

The following information is based on "Urinary tract infection: diagnosis, treatment and long-term management of urinary tract infection in children, NICE Clinical Guidance, August 2007".¹ Although these guidelines are not without controversy.²

The diagnosis of UTI in young children is important as a marker for urinary tract abnormalities. It may be associated with life-threatening sepsis in the newborn.

• Bacteriuria; bacteria in urine uncontaminated by urethral flora. It may be occult i.e. few, or unreported symptoms. It should be considered significant in infants/early-school-age children where it may lead to renal scarring.³
• Symptomatic bacteriuria; this term is synonymous with UTI, which may involve different urinary tract sites.
• Chronic pyelonephritis; this is a histological/radiological diagnosis. Juxtaposition of a renal cortical scar and a dilated calyx is the key to its diagnosis. It is a major cause of renal failure. During micturition, urine flow may be retrograde up the ureters. This is called reflux, and it is identified by a micturating cystourethrogram (MCUG).

• UTI is one of the most common bacterial infections of childhood, affecting up to 10% by the teenage years.^4,5
• The incidence in infants is up to 1%, but as high as 10% in low-birth-weight infants.
• UTI before age one occurs more frequently in boys than in girls.
• After age one, infection is more common in girls.
• 40% of children with UTI will have radiological abnormalities e.g. reflux, malpositions, duplications, megaureter and hydronephrosis. New scars are common in all ages.⁶
• During 2004/2005 12,256 children under the age of 15 years were admitted to hospital in England with a primary diagnosis of urinary tract infection.⁷

Risk factors

• Any condition that leads to urinary stasis (renal calculi, obstructive uropathy, vesicoureteric reflux - or family history of, voiding disorders) or poor urine flow e.g. phimosis
• History suggestive of, or confirmed previous UTI
• Constipation
• Evidence of spinal lesion
• Antenatally-diagnosed renal abnormality
• Poor growth
• High blood pressure

• Infants younger than 3 months; fever, vomiting, lethargy and irritability are common. Poor feeding and failure to thrive may occur. Abdominal pain, jaundice, haematuria and offensive urine are less common.¹
• Infants and preverbal children 3 months or older commonly have a fever. Fewer also have abdominal pain, loin tenderness, vomiting and poor feeding. Lethargy, irritability, haematuria, offensive urine and failure to thrive are less common.
• Verbal children most commonly present with frequency and dysuria. Dysfunctional voiding, changes to continence, abdominal pain and loin tenderness are less common. Fever, malaise, vomiting, haematuria, offensive urine and cloudy urine are least likely to be seen in this group.
• Gastroenteritis may co-exist with UTI, although true incidence of this unknown due to urine sample contamination.

• Vulvovaginitis
• Urethritis
• Irritation (use of soaps, bubble baths, poor hygiene)
• Threadworm infestation
• Balanitis

Collecting the urine sample

A clean catch urine sample is the NICE recommended method for urine collection. This is much easier in toilet-trained children.
If a clean catch urine sample is not possible:

• Use other non-invasive methods such as urine collection pads, but do not use cotton wool balls, gauze or sanitary towels.
• Alternatively a catheter sample or suprapubic aspiration (SPA) may be collected where there is sufficient experience and resources. The decreased contamination rate offered by either of these methods offsets the disadvantage of being an invasive procedure. They may be most appropriate in:
  • Infants
  • Pre-toilet-trained children with fever and no focus, or where UTI is considered likely
  • Children with a history of UTI/vesico-ureteric reflux/on UTI prophylaxis/having renal tract anomalies
  • Very sick children

If the sample needs to be cultured but cannot be cultured within 4 hours of collection, either refrigerate or preserve it with boric acid immediately.

Diagnosis

• Aged <3 months; if UTI suspected clinically refer to paediatrician
• Aged >3months but <3 years send a sample for urgent microscopy and culture. Await result before starting treatment, unless they are very systemically unwell.
• Aged >3 years use dipstick test to diagnose UTI:
  • If leucocyte esterase and nitrite are positive start antibiotic treatment for urinary tract infection and if child has high or intermediate risk of serious illness or a history of infection, send urine sample for culture
  • If leucocyte esterase is negative and nitrite is positive start antibiotic treatment if fresh sample was tested and send urine sample for culture
  • If leucocyte esterase is positive and nitrite is negative send urine sample for microscopy and culture. Only start antibiotic treatment for urinary tract infection if there is good clinical evidence of such infection.
  • If leucocyte esterase and nitrite are negative do not start treatment for urinary tract infection and explore other causes of illness.

Imaging

These are based on NICE guidelines, but there is still some debate. These are usually arranged by secondary care.
Imaging guidelines for children less than 6 months old

General principles

• Children with a high risk of serious illness and/or younger than 3 months should be referred immediately to secondary care. This should be assessed in accordance with NICE Guidance "Feverish illness in children".⁸
• Do not delay treatment if the sample cannot be obtained and the infant or child is at high risk of serious illness.

Carefully assess the degree of toxicity, dehydration and ability to maintain oral fluid intake. Encourage fluids, avoid or correct constipation, encourage full voiding.

Pharmacological

• Consider referral to secondary care for children aged 3 months and older with acute pyelonephritis or upper urinary tract infection, but if appropriate treat with 10 days of oral antibiotics.
• If child is unable to tolerate oral antibiotics, start treatment with intravenous antibiotics until oral intake is possible.
• Children aged 3 month and over with cystitis or lower urinary tract infection should be treated with three days of oral antibiotics according to local guidance.⁹ A Cochrane systematic review suggests that treatment for 2 - 4 days seems to be as effective as treatment for 7 - 14 days for eradicating lower tract UTI in children.¹⁰ Carers should be advised to return for review if the child remains unwell after 24-48 hours.
• There is little evidence to favour a particular antimicrobial.
  • Trimethoprim 50 mg/5 ml, 50 mg b.d. orally¹¹ is commonly used, however, it is not recommended for patients with renal insufficiency.
  • Other agents used include cefalexin (expensive, some resistance), amoxicillin (not useful for empirical treatment as high resistance rates, but good for known sensitive organisms), co-amoxiclav is a useful second line agent. NB: Quinolones should be avoided due to safety concerns.

• Use oral cephalosporins or short courses of IV therapy (2 - 5 days) followed by oral therapy. Single daily dosing for aminoglycosides appears to be safe and effective.¹²
• Paracetamol relieves pain and high temperature.
• Treatment of reflux; consider antibiotic prophylaxis.¹³
• Repeat MSU after treatment.

Most children recover quickly and completely with antibiotic treatment.
Recurrence of urinary tract infection is more likely in:

• Younger children i.e. aged less than 6 months
• Girls compared to boys
• Vesicoureteral reflux grade 3 - 5, compared with reflux grade 1- 2, or no reflux
• Dysfunctional voiding syndrome;¹⁴ this is an abnormality of emptying, due to either a small-capacity, unstable bladder or a large-capacity, poorly emptying bladder.

Vesicoureteric reflux (VUR) is found in about 1% of normal infants and normally resolves over several years.¹⁵ However, it is a risk factor for pyelonephritis, which can cause renal scarring, which can lead to hypertension and impaired renal function.

A common sense approach is advised given the lack of conclusive evidence.¹⁶
Recent NICE Guidance does NOT advocate the use of routine antibiotic prophylaxis.¹
Relief of voiding dysfunction, good hygiene, wiping from front to back after micturition in girls, avoiding constipation, bubble baths, chemical irritants and tight clothing are sensible recommendations.

• Children with significant urinary tract abnormalities and/or frequent symptomatic UTI may benefit from prophylactic antibacterials (trimethoprim or nitrofurantoin).¹³ Prophylactic antibiotics are rarely indicated and should not be initiated in primary care.⁹

Just one episode of reflux of infected urine may initiate chronic pyelonephritis, so screening for bacteriuria is useless.¹⁶ But once a UTI is suggested e.g. by urine microscopy in an infant, treat it at once before culture sensitivities are known, as renal damage may be about to happen.
As the overall sibling incidence of VUR has been estimated to be approximately 30%, siblings should be screened for reflux.¹⁶