Introduction

Urinary tract infection is among the most common bacterial infections in children. It occurs in approximately 1% of boys and 3% of girls during childhood. Urine is an excellent culture medium and if there is residual urine after voiding, there is a significant risk for developing UTI which can occur at any age.

Epidemiology

• In neonates, boys are more likely to have UTI than girls owing to the higher incidence of congenital urinary tract abnormalities in males.
• The prevalence of UTIs varies with age. During the 1st year of life, the male : female ratio is 2.8–5.4 : 1. Beyond 1–2 year, there is a striking female preponderance, with a male : female ratio of 1 : 10.
• Female infants and children have a higher incidence of UTI than males because they have shorter urethras, a greater predisposition to dysfunctional voiding and a higher prevalence of vesicoureteral reflux.
• Females are more prone to UTI when they become sexually active.

Aetiology

• 75–90% of all UTI are caused by Escherichia coli, followed by Klebsiella spp. and Proteus spp.
• Klebsiella, Enterobacter, Proteus, Pseudomonas, Enterococcus and Candida are encountered in the presence of obstruction, instrumentation and poor immune state. Klebsiella is a common etiology in neonates.

Pathogenesis

• Virtually all UTIs are ascending infections, rarely, renal infection may occur by hematogenous spread, as in endocarditis or in some neonates.
• The bacteria arise from the fecal flora, colonize the perineum, and enter the bladder via the urethra.
• In uncircumcised boys, the bacterial pathogens arise from the flora beneath the prepuce.
• The bacteria causing cystitis may ascend to the kidney to cause pyelonephritis.
• The pathogenesis of UTI is based in part on the presence of bacterial pili or fimbriae on the bacterial surface with which they adhere to the epithelial cells.
• Some E. coli possess invasive toxins and hemolysins and are more pathogenic.

Risk factors

• Female gender
• Obstructive uropathy
• Vesicoureteral reflux
• Neurogenic bladder
• Uncircumcised male
• Urethra instrumentation
• Wiping from back to the front in female after defecation
• Constipation
• Immunosuppression 

Clinical features

The 3 basic forms of UTI are pyelonephritis, cystitis, and asymptomatic bacteriuria.

Clinical pyelonephritis is characterized by any or all of the following: abdominal or flank pain, fever, malaise, nausea, vomiting, and, occasionally, diarrhea.

• Newborns may show nonspecific symptoms such as poor feeding, irritability, and weight loss
• In younger children it is non-specific and may include fever, vomiting,poor feeding, diarrhoea, failure to thrive, micturitional cry
• In older children there is dysuria, frequency and urgency of micturition, haematuria, loin pain (Renal angle tenderness)

Cystitis indicates that there is bladder involvement; symptoms include dysuria, urgency, frequency, suprapubic pain, incontinence, and malodorous urine.

Asymptomatic bacteriuria refers to a condition that results in a positive urine culture without any manifestations of infection.

Investigation

• Urinalysis: detection of leucocyte esterase and nitrite.
• Urine microscopy, culture, and sensitivity (m/c/s): Appearance of the urine may be turbid, Presence of WBC cast on urine microscopy.
  • Diagnosis is confirmed by urine culture when it is 10⁵ or more bacterial per ml.
  • Any colony growth obtained by suprapubic aspiration is significant.
  • Microscopy of un-centrifuged urine showing more than 10WBC/cu mm is abnormal.
  • If the culture shows >100,000 colonies of a single pathogen, or if there are 10,000 colonies and the child is symptomatic, the child is considered to have a UTI.
• FBC
• Blood culture
• E/U/Cr
• Plain abdominal X-ray
• Abdominopelvic USS
• Intravenous urography

Treatment

• Encourage liberal fluid intake.
• Regular bladder emptying to prevent stasis.
• Give antibiotic according to culture result. Before results come out, commence empirical antibiotics treatment.
• UTI in early infancy is often associated with sepsis; treatment should be with a combination of parenteral ampicillin with an aminoglycoside for 10-14 days. Alternatively a third generation cephalosporin can be used
• UTI in older children; the management depends on the severity, if pyelonephritis is suspected antibiotics are given parenteral initially as above and antibiotics are changed to oral once toxicity resolves
• In patients who are not toxic and are tolerating orally, amoxicillin, co-amoxiclav, cephalexin or cefixime for 10days.
• Patients are followed up with repeat urine m/c/ s
• Surgical intervention in cases of obstruction.
• Long term prophylaxis in UTI in patients that fall into any of these categories:
  • Age 3yrs being investigated for the underlying cause of UTI
  • Recurrent UTI of ≥3episodes in one year being investigated for the underlying cause
  • UTI  with vesicoureteral reflux(VUR)
  • e.g. of drugs used as prophylaxis are; cotrimoxazole,nitrofurantoin,