Case studies from the British National Formulary for Children — urinary tract infections
Urinary tract infections: A four-year-old girl presents with a 24-hour history of urinaryfrequency and dysuria. Examination is unremarkable apart from mildsuprapubic tenderness. She has idiopathic hypoparathyroidism, but thereis no other medical history of note. A urine sample is positive forleucocyte esterase and nitrite on dipstick testing
A four-year-old girl presents with a 24-hour history of urinaryfrequency and dysuria. Examination is unremarkable apart from mildsuprapubic tenderness. She has idiopathic hypoparathyroidism, but thereis no other medical history of note. A urine sample is positive forleucocyte esterase and nitrite on dipstick testing.
Is it necessary to send a urine sample for culture and sensitivity testing?
The clinical findings and the results of dipstick testing arediagnostic of a urinary tract infection (UTI). Given that the child isover three years of age, this is her first UTI, and that she has anuncomplicated infection of the lower urinary tract, it is not routinelynecessary to send a urine sample for culture and sensitivity testing inthis case.
How should the child’s UTI be treated?
Table 1, section 5.1, BNFC 2008, advises that trimethoprim,nitrofurantoin or an oral cephalosporin (eg, cefalexin) can be used forthe initial treatment of an uncomplicated lower UTI. As resistance totrimethoprim is relatively common in some areas, local antibioticsusceptibility data should be consulted before choosing this antibioticfor empirical therapy. Amoxicillin should only be used if the organismcausing the UTI is known to be sensitive to it.
The antibiotic should be given for three days. The parents or carersshould be advised to bring the child back for re-assessment if she isunwell 24–48 hours after the initial assessment.
Does the child require any antibiotic prophylaxis or long-term follow-up?
Imaging tests of the urinary tract are not indicated for children inthis age group with a first-time UTI that is uncomplicated and whichresponds to antibiotic treatment within 48 hours.
The prescribing notes in section 5.1.13, BNFC 2008, recommendantibiotic prophylaxis for children with recurrent infection,significant urinary tract anomalies, or significant kidney damage.Although antibiotic prophylaxis is not recommended for this child,general advice should be provided on preventing UTIs, such asmaintaining an adequate intake of fluid and avoiding a delay invoiding.
The child’s first UTI is treated successfully with a three-daycourse of trimethoprim. Five months later, the child presents withfever (temperature 39C), rigors, vomiting and loin pain, as well aslocal urinary symptoms. She is dehydrated to the extent thatintravenous fluids are required. It is noted that she is takingCalcium-Sandoz syrup as treatment for her hypoparathyroidism. An in-outcatheter urine sample is positive for leucocyte esterase and nitrites.The remainder of the urine sample is sent to the laboratory for urgentprocessing. Microscopy shows >100 leucocytes mm3 and the presence of numerous Gram-negative bacilli.
On this occasion the patient has clinical signs of acute pyelonephritis. Gram-negative bacilli, especially Escherichia coli,are the most common causes of UTI. Because the clinical picture issuggestive of septicaemia a blood culture should be collected beforestarting antibiotic treatment.
How should the child’s acute pyelonephritis be treated?
The prescribing notes in section 5.1.13, BNFC 2008, advise thatacute pyelonephritis can be treated with a first generationcephalosporin or co-amoxiclav for seven to 10 days. If the child isseverely ill then the infection is best treated initially byintravenous injection of a broad-spectrum antibacterial, such ascefotaxime or co-amoxiclav.
Because this child is severely ill and vomiting, she should bestarted on an intravenous antibiotic. A switch to oral therapy shouldoccur after two to four days as her condition improves. Treatmentshould be modified according to the results of culture and sensitivitytesting and clinical response.
Why should ceftriaxone be avoided in this child?
According to the ceftriaxone monograph in BNFC 2008, dehydrationincreases the risk of ceftriaxone precipitation in the gall bladder.The concomitant use of ceftriaxone and calcium should be avoidedbecause there is a risk of precipitation in the urine and lungs ofneonates (and possibly infants and older children); it is not clear ifthis risk also applies to oral calcium supplements.
For this child, who is dehydrated and receiving calcium supplements,treatment with cefotaxime would be more appropriate. Alternatively,co-amoxiclav can be given, but it is advisable to maintain adequatehydration with high doses (particularly during parenteral therapy) toreduce the possibility of amoxicillin crystalluria.
What further management is required?
An ultrasound of the urinary tract should be performed to identifyany structural abnormalities of the urinary tract. Because the child isseriously ill, this should ideally be undertaken during the acuteinfection, and certainly within six weeks of her illness.
Because she has now experienced two UTIs she should also have adimercaptosuccinic acid (DMSA) scintigraphy scan after four to sixmonths to detect renal parenchymal damage. If she develops another UTIbefore the DMSA scan, consideration should be given to carrying it outsooner.
Considering the severity of this second UTI, antibiotic prophylaxisshould be considered with low doses of either trimethoprim ornitrofurantoin. The need to continue prophylaxis should be reviewedwhen the scan results are available.
Birmingham Children’s Hospital
BNFC clinical adviser
Citation: The Pharmaceutical Journal URI: 10039212
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