The following information is based on "Urinary tract infection: diagnosis, treatment and long-term management of urinary tract infection in children", National Institute for Health and Clinical Excellence (NICE) Clinical Guidance, August 2007.¹ However, these guidelines were not without criticism.²

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

Definitions

• 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 an 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).

Epidemiology

• 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-birthweight infants. It varies depending on age and sex.
• In the first year of life (mostly the first 3 months), UTI is more common in boys (3.7%) than in girls (2%), after which the incidence changes, to approximately 3% in girls and 1.1% in boys.⁶
• Paediatric UTI is the most common cause of fever of unknown origin in boys aged less than 3 years.
• 40% of children with UTI will have radiological abnormalities, e.g. reflux, malpositions, duplications, mega-ureter and hydronephrosis. New scars are common in all ages.⁷
• During 2009/2010, 15,310 children under the age of 15 years were admitted to hospital in England with a primary diagnosis of UTI.⁸

Risk factors

• Any condition that leads to urinary stasis (renal calculi, obstructive uropathy, vesico-ureteric reflux (VUR) - 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.

Presentation

• 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 aged 3 months or older: these 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: these 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 is unknown, due to urine sample contamination.

Differential diagnosis

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

Investigations

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) of urine may be collected where sufficient experience and resources exist. 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 (VUR)/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 is suspected clinically, refer to a paediatrician.
• Aged >3 months 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 leukocyte esterase and nitrite are positive: start antibiotic treatment for UTI and, if the child has a high or intermediate risk of serious illness or a history of infection, send urine sample for culture.
  • If leukocyte esterase is negative and nitrite is positive: start antibiotic treatment if a fresh sample was tested and send urine sample for culture.
  • If leukocyte esterase is positive and nitrite is negative: send urine sample for microscopy and culture. Only start antibiotic treatment for UTI if there is good clinical evidence of such infection.
  • If leukocyte esterase and nitrite are negative: do not start treatment for UTI, 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:

Management

General principles

• Children with a high risk of serious illness and/or aged younger than 3 months should be referred immediately to secondary care. This should be assessed in accordance with NICE Guidance "Feverish illness in children".⁹
• 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, and encourage full voiding.

Pharmacological

• Consider referral to secondary care for children aged 3 months and older with acute pyelonephritis or upper UTI but, if appropriate, treat with 10 days of oral antibiotics.
• If the child is unable to tolerate oral antibiotics, start treatment with intravenous (IV) antibiotics until oral intake is possible.
• Children aged 3 months and over with cystitis or infection of the lower urinary tract should be treated with three days of oral antibiotics according to local guidance.¹ A Cochrane systematic review suggests that treatment for 2-4 days seems to be as effective as treatment for 7-14 days for eradicating infection of the lower urinary tract in children.¹⁰ However, another meta-analysis disputes that conclusion, and the European Association of Urology also does not advise short courses of antibiotics in children.^6,11 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 bd orally 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 there are high resistance rates, but good for known sensitive organisms), and co-amoxiclav, which 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 midstream specimen of urine after treatment.

Prognosis

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

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

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.

Prevention

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.^1,17 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 However, prophylactic antibiotics are rarely indicated and should not be initiated in primary care.¹

Just one episode of reflux of infected urine may initiate chronic pyelonephritis, so screening for bacteriuria is useless.¹⁶ However, 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 vesico-ureteric reflux (VUR) has been estimated to be approximately 30%, siblings should be screened for reflux.¹⁶

Document references

1. Urinary tract infection in children: diagnosis, treatment and long-term management, NICE Clinical Guideline (2007)
2. Coulthard MG; Nasty processes produce nasty guidelines. BMJ September 2007
3. Raz R; Asymptomatic bacteriuria. Clinical significance and management. Int J Antimicrob Agents. 2003 Oct;22 Suppl 2:45-7. [abstract]
4. Coulthard MG, Lambert HJ, Keir MJ; DMSAs after UTI: scan more children, not less. Archives of Disease in Childhood 85(4), 348. 2001
5. Jakobsson B, Esbjorner E, Hansson S; Minimum incidence and diagnostic rate of first urinary tract infection. Pediatrics, 1999
6. Guidelines on Urological Infections, European Association of Urology (2011)
7. Benador D, Benador N, Slosman D, et al; Are younger children at highest risk of renal sequelae after pyelonephritis? Lancet. 1997 Jan 4;349(9044):17-9. [abstract]
8. Hospital Episode Statistics, The NHS Information Centre (2010); Primary diagnosis: summary 2009-10
9. Feverish illness in children - Assessment and initial management in children younger than 5 years, NICE Clinical Guideline (2007)
10. Michael M, Hodson EM, Craig JC, Martin S, Moyer VA; Short versus standard duration oral antibiotic therapy for acute urinary tract infection in children. Cochrane Data Sys Review (2):CD003966. 2005.
11. Keren R, Chan E; A meta-analysis of randomized, controlled trials comparing short- and long-course antibiotic therapy for urinary tract infections in children. Pediatrics. 2002 May;109(5):E70-0. [abstract]
12. Bloomfield P, Hodson EM, Craig JC; Antibiotics for acute pyelonephritis in children. Cochrane Data Sys Review (2):CD003772. 2005.
13. Le Saux N, Pham B, Moher D; Evaluating the benefits of antimicrobial prophylaxis to prevent urinary tract infections in children: a systematic review. CMAJ. 2000 Sep 5;163(5):523-9. [abstract]
14. Hansson S; Urinary incontinence in children and associated problems. Scand J Urol Nephrol Suppl. 1992;141:47-55; discussion 56-7. [abstract]
15. Jakobsson B, Jacobson SH, Hjalmas K; Vesico-ureteric reflux and other risk factors for renal damage: identification of high- and low-risk children. Acta Paediatr Suppl. 1999 Nov;88(431):31-9. [abstract]
16. Smellie JM, Poulton A, Prescod NP; Retrospective study of children with renal scarring associated with reflux and urinary infection. BMJ. 1994 May 7;308(6938):1193-6. [abstract]
17. Mori R, Fitzgerald A, Williams C, et al; Antibiotic prophylaxis for children at risk of developing urinary tract Acta Paediatr. 2009 Nov;98(11):1781-6. Epub 2009 Jul 22. [abstract]

Internet and further reading

• Mori R, Lakhanpaul M, Verrier-Jones K; Diagnosis and management of urinary tract infection in children: summary of NICE guidance. BMJ. 2007 Aug 25;335(7616):395-7.