Urinary tract infection in childhood

Urine is liquid waste product of the body. It is produced by the kidneys by a complex and ingenious process of filtration of water from blood along with a concentration of waste products. These wastes are produced by metabolic processes and are high in nitrogen-containing compounds, such as urea. The latter is highly useful in the process of dyeing of fabrics. Urine trickles down the ureters, two narrow tubes that pass urine down to the bladder, where it is stored and conveniently voided when required, a process technically known as urination. This is the body’s primary method of eliminating unwanted water-soluble chemicals from the body. The concentrations of these chemicals can be detected and analysed by urinalysis, a simple test that can be done even in pharmacies and clinics e.g. for the detection of glucose in diabetes. Amniotic fluid, which surrounds and suspends babies in the womb, consists primarily of urine produced by the baby.

Urinary tract infection (UTI) is a common infection in childhood. Urine does not contain bacteria (germs) unless it is infected. Infection can reach the urinary tract from the skin around the rectum and genitals and through the bloodstream from any other infected part of the body. Various sites of the urinary tract may become infected in isolation or in combination, and these parts include:

• the kidneys (causing pyelonephritis)
• the bladder (causing cystitis)
• the urethra (causing urethritis)

UTI affects up to two per cent of school-aged children and is commoner in girls, in individuals who are immunosuppressed (e.g. chemotherapy treatment for cancer) and in association with congenital malformations of the urinary tract. Uncircumcised boys have slightly more UTIs than those who have been circumcised.

Signs of a UTI may be unremarkable, especially in infants, and may therefore remain untreated with potentially serious health problems. Infants may only have fever, or may have vomiting or diarrhoea mimicking gastroenteritis. Older children will complain of pain on passing urine, or tummy pain or may need to urinate frequently, similar to adult symptoms of urinary tract infection.

The diagnosis in childhood of UTI, especially in infancy, is extremely important because of the potential catastrophic complications that may arise in later life.

UTI may lead to renal damage that may cause high blood pressure, which if undetected and untreated, may lead to progressive kidney disease with renal failure requiring dialysis and renal transplantation.

The risk of high blood pressure after renal damage is estimated at 10-20 per cent. It is therefore crucial to confirm the diagnosis of UTI, because a firm diagnosis will necessitate tests looking for established renal damage or risk factors that may result in the future development of such damage if UTI recurs. These tests include both ultrasound and special x-rays.

The diagnosis can only be established by the collection of urine that is sent to the laboratory to check for bacterial growth, i.e. evidence of UTI. Urine must be collected prior to the administration of antibiotics. Urine may be collected via a variety of ways – the attending doctor will explain. Antibiotics may be started after urine collection, before a result becomes available, especially if a UTI is strongly suspected. In children, it is also useful to recheck the urine after antibiotic treatment in order to confirm that the infection has indeed been eliminated from the urinary tract.

In conclusion, it is crucial to accurately diagnose UTI in childhood due to the potential long-term complications. It is equally important to be certain of UTI as the imaging investigations are extensive and invasive.

Further reading

Urinary tract infections in children: Why they occur and how to prevent them - http://www.aafp.org/afp/980515ap/980515d.html

Kids Health: Urinary tract infections - http://kidshealth.org/parent/infections/common/urinary.html

Urinary tract infections – American Academy of Paediatrics - http://www.medem.com/medlb/article_detaillb_for_printer.cfm?article_ID=ZZZIZ112R7C&sub_cat=107

Symptoms of urinary tract infections – American Academy of Paediatrics - http://www.medem.com/medlb/article_detaillb_for_printer.cfm?article_ID=ZZZ9159YQ7C&sub_cat=107

Prof. Grech is a consultant paediatrician and associate professor of paediatrics at the University of Malta.