Urinary tract infections in children younger than 5 years of age: epidemiology, diagnosis, treatment, outcomes and prevention.

Although the true incidence of urinary tract infections (UTIs) in children is difficult to estimate, they are one of the most common bacterial infections seen by clinicians who care for young children. Except for the first 8 to 12 weeks of life, when infection of the urinary tact may be secondary to a haematogenous source, UTI is believed to arise by the ascending route after entry of bacteria via the urethra. Enterobacteriaceae are the most common organisms isolated from uncomplicated UTI. Infection with Staphylococcus aureus is rare in children without in-dwelling catheters or other sources of infection, and coagulase-negative staphylococci and Candida spp. are associated with infections after instrumentation of the urinary tract. The diagnosis of UTI in young children is important as it is a marker for urinary tract abnormalities and, in the newborn, may be associated with bacteraemia. Early diagnosis is critical to preserve renal function of the growing kidney. A urine specimen for culture is necessary to document a UTI in a young child. Prior to culture, urinalysis may be useful to detect findings supporting a presumptive diagnosis of UTI. The goals of the management of UTI in a young child are: (i) prompt diagnosis of concomitant bacteraemia or meningitis, particularly in the infant; (ii) prevention of progressive renal disease by prompt eradication of the bacterial pathogen, identification of abnormalities of the urinary tract and prevention of recurrent infections; and (iii) resolution of the acute symptoms of the infection. Delay in initiation of the antibacterial therapy is associated with an increased risk of renal scarring. The initial choice of antibacterial therapy is based on the knowledge of the predominant pathogens in the patient's age group, antibacterial sensitivity patterns in the practice area, the clinical status of the patient and the opportunity for close follow-up. Imaging studies to detect congenital or acquired abnormalities are recommended following the first UTI in all children aged <6 years. Patients with significant urinary tract abnormalities and/or frequent symptomatic UTI may benefit from prophylactic antibacterials. The main long term consequence of UTI is renal scarring which may lead to hypertension and end-stage renal disease. Prevention of recurrent UTI focuses on detection, and correction if possible, of urinary tract abnormalities. Interventions that have been associated with a decrease in symptomatic UTI in children with a history of recurrent UTI include relief of constipation and voiding dysfunction.