Management of urinary tract infection in children

Abstract

New NICE guidelines emphasise prompt diagnosis and treatment but more restrained imaging

This week's BMJ contains two articles about the diagnosis and management of urinary tract infections in children.^{1 2} The first is a summary of the recently published guidelines from the National Institute for Health and Clinical Excellence (NICE) on the diagnosis and management of such infections.¹ The second is a multicentre randomised controlled trial comparing exclusive oral antibiotic treatment with antibiotic treatment started parentally and completed orally in children with a first episode of acute pyelonephritis.³ What do these articles add to current knowledge about how best to diagnose and treat urinary tract infections in children?

The 1991, UK guidelines on acute urinary tract infections in childhood were prompted by the great variation in management of this condition.⁴ They emphasised that urinary tract infections and vesicoureteric reflux can cause scarred kidneys (reflux nephropathy), leading to hypertension and chronic renal failure. US guidelines also emphasised the need to diagnose, treat promptly, and investigate children with a confirmed urinary tract infection, especially those under 2 years of age who are at greatest risk of renal damage.⁵

Enthusiasm for extensively investigating children with urinary tract infections for vesicoureteric reflux has lessened with the finding of globally “scarred” kidneys due to dysplasia in infants born with antenatally detected urinary tract abnormalities, gross vesicoureteric reflux, and no urinary tract infection. In addition, the widespread use of dimercaptosuccinic acid renal scintigraphy has revealed parenchymal defects in many kidneys after infection that do not develop into renal scarring. Indeed, many scars are present in the absence of demonstrable reflux.⁶ As most children with urinary tract infection will only ever have one infection and have a normal urinary tract, enthusiasm for investigations beyond an initial ultrasound has waned. Also, micturating cystourethrography and radionuclide scans can be traumatic for children and families.⁷

The NICE guidelines summarised in this issue have been eagerly awaited.¹ They deal with some of the problems in diagnosing urinary tract infections in young infants—the diagnosis is not even thought of and urine cultures are not taken appropriately. The younger the child the more non-specific the symptoms are—for example, lethargy, irritability, malaise, failure to thrive, poor feeding, vomiting, jaundice.

A key feature is that urinary tract infection should be considered in any child with unexplained fever of 38° or higher, and the guidelines cross refer to a recent NICE clinical guideline on feverish illness in children.⁸ History taking and clinical examination are paramount, including whether any abnormalities were noted on antenatal ultrasound and whether the family has a history of urinary tract problems. Vesicoureteric reflux can have a 30% familial incidence.

Urinary tract infection is defined as symptoms and a pure growth of 10⁵ organisms/ml on a clean voided specimen. General practitioners predominantly deal with women with lower urinary tract symptoms who can produce a midstream specimen of urine. Obtaining urine samples from incontinent children is extremely difficult and needs to be performed with diligence.

The NICE guidelines state that parents and carers should be helped to make decisions about their child's care in partnership with healthcare professionals. Because proving that a urine infection exists affects treatment and investigations, parents should be involved in the decision about whether to obtain urine by clean catch or using a urine collection pad or bag.⁹ If urine cannot be sampled in primary care then the child should be referred to hospital, where a catheter sample or suprapubic aspirate can be attempted (preferably under ultrasound guidance), especially in the sick febrile younger child.¹

Dipstick testing for leucocytes and nitrite is increasingly used, but positive results still require careful interpretation.¹⁰ The urine needs to be cultured unless both leucocytes and nitrite are negative and there are no symptoms. Microscopy of fresh urine for white cells and bacteria can give a strong indication of urinary tract infections, but general expertise in this area has greatly diminished. Microbiology laboratories are often overwhelmed with urine specimens from adult patients and are developing flow cytometer methods for handling urine specimens.¹¹ As a consequence, laboratory technicians may have reduced expertise when asked to perform microscopy out of hours, and this requires research in the paediatric setting.

Ten days of antibiotic treatment are recommended if the child is febrile and has a suspected upper urinary tract infection. Oral antibiotics are advocated unless oral intake is not possible, when treatment should be intravenous.³ This approach is supported by the study in this issue by Montini and colleagues.² The multicentre randomised non-inferiority trial of 502 children with a first attack of pyelonephritis randomised children to receive either amoxicillin plus clavulinic acid for 10 days or parenteral ceftriaxone for three days followed by oral amoxicillin plus clavulinic acid for a further seven days.² No significant differences were seen between orally or parenterally treated children on the primary outcome of scarring on dimercaptosuccinic acid scans at 12 months, or on the secondary outcomes such as reduction of fever, blood counts, or urine sterilisation rates. As a cannula is often in place for initial sampling of blood cultures and electrolytes, most sick children will probably receive initial parenteral treatment. Of note, 10% of the children in Montini's study who started oral treatment were switched to intravenous treatment due to diarrhoea or vomiting caused by antibiotics or intercurrent rotavirus gastroenteritis.

Most children with urinary tract infections will have lower tract symptoms and will be systemically well. The NICE guidelines follow a recent systematic review in stating that such children can be treated with three days of oral antibiotics according to local guidance and sensitivities.¹²

The statement that the routine prescription of prophylactic antibiotics is no longer supported will surprise many, but evidence is accumulating that prophylactic antibiotics do not significantly decrease the risk of recurrent urinary tract infections and may increase the risk of resistant organisms.¹³

The imaging strategies will provoke even more debate. Much relies on using non-invasive ultrasound to determine the status of the urinary tract. In children who are systemically well, only those under 6 months or with recurrent infections need an ultrasound scan. Routine imaging to identify vesicoureteric reflux is not recommended, and only in children under 6 months should a micturating cystourethrogram be requested when there is severe or atypical illness, or recurrent urinary tract infections.¹

Many specialists may think the guidelines downplay the importance of urinary tract infections in childhood, but the opposite may be the case. Linking the guidelines to the management of febrile illness emphasises the importance of such infections as a cause of unexplained fever, and this may improve the detection rate in vulnerable infants in both primary and secondary care.

Children with atypical features and recurrent urinary tract infections also need appropriate referral and investigation, but watchful waiting can be used in those over 6 months who remain well or have a negative history and only lower tract symptoms. The parent or carer should be informed about the importance of a diagnosis of urinary tract infection and be involved in obtaining urine samples, especially during febrile episodes if prophylaxis is not used.¹