A 4-year old girl presents with a 24-hour history of urinary frequency and dysuria. Examination is unremarkable apart from mild suprapubic tenderness. She has idiopathic hypoparathyroidism, but there is no other medical history of note.
A urine sample is positive for leucocyte esterase and nitrite on dipstick testing.
The clinical findings and the results of dipstick testing are diagnostic of a urinary tract infection (UTI). Given that the child is over 3 years of age, this is her first UTI, and that she has an uncomplicated infection of the lower urinary tract, it is not routinely necessary to send a urine sample for culture and sensitivity testing in this case.
Table 1, section 5.1, BNFC 2008, advises that trimethoprim, nitrofurantoin, or an oral cephalosporin (e.g. cefalexin) can be used for the initial treatment of an uncomplicated lower UTI. As resistance to trimethoprim is relatively common in some areas, local antibiotic susceptibility data should be consulted before choosing this antibiotic for empirical therapy. Amoxicillin should only be used if the organism causing the UTI is known to be sensitive to it.
The antibiotic should be given for 3 days. The parents or carers should be advised to bring the child back for re-assessment if she is unwell 24–48 hours after the initial assessment.
Imaging tests of the urinary tract are not indicated for children in this age group with a first-time UTI that is uncomplicated and which responds to antibiotic treatment within 48 hours.
The prescribing notes in section 5.1.13, BNFC 2008, recommend antibiotic 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 as maintaining an adequate intake of fluid and avoiding a delay in voiding.
The child's first UTI is treated successfully with a 3 day course of trimethoprim. 5 months later the child presents with fever (temperature 39°C), rigors, vomiting and loin pain, as well as local urinary symptoms. She is dehydrated to the extent that intravenous fluids are required. It is noted that she is taking Calcium-Sandoz syrup as treatment for her hypoparathyroidism. An in-out catheter urine sample is positive for leucocyte esterase and nitrites. The remainder of the urine sample is sent to the laboratory for urgent processing. 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 E. coli, are the most common causes of UTI. Because the clinical picture is suggestive of septicaemia a blood culture should be collected before starting antibiotic treatment.
The prescribing notes in section 5.1.13, BNFC 2008, advise that acute pyelonephritis can be treated with a first generation cephalosporin or co-amoxiclav for 7–10 days. If the child is severely ill then the infection is best treated initially by intravenous injection of a broad-spectrum antibacterial such as cefotaxime or co-amoxiclav.
As this child is severely ill and vomiting, she should be started on an intravenous antibiotic. A switch to oral therapy should occur after 2-4 days as her condition improves. Treatment should be modified according to the results of culture and sensitivity testing and clinical response.
According to the ceftriaxone monograph in BNFC 2008, dehydration increases the risk of ceftriaxone precipitation in the gall bladder. The concomitant use of ceftriaxone and calcium should be avoided because there is a risk of precipitation in the urine and lungs of neonates (and possibly infants and older children); it is not clear if this 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 adequate hydration with high doses (particularly during parenteral therapy) to reduce the possibility of amoxicillin crystalluria.
An ultrasound of the urinary tract should be performed to identify any structural abnormalities of the urinary tract. Because she is seriously ill, this should ideally be undertaken during the acute infection, but certainly within 6 weeks of her illness. Because she has now experienced two UTIs she should also have a dimercaptosuccinic acid (DMSA) scintigraphy scan after 4-6 months to detect renal parenchymal damage. If she develops another UTI before the DMSA scan, consideration should be given to carrying it out sooner.
Considering the severity of this second UTI, antibiotic prophylaxis should be considered with low doses of either trimethoprim or nitrofurantoin. The need to continue prophylaxis should be reviewed when the scan results are available.