Q. What is UTI ?

A. Urinary tract infection is a bacterial invasion of kidneys and the urinary tract. It is designated as pyelonephritis or upper UTI when the infection involves mainly renal parenchyma and pelvicalyceal system. Lower UTI involves infection of urinary bladder and urethra.

Q. What are the causes of UTI?

A. UTI is predominantly caused by enterococci like certain strains of E.Coli and other gram negative bacilli such as Proteus, Klebsiella, and Pseudomonas, which are uropathogenic. It is rarely caused by tubercular bacilli.

In children below the age of 3-4 years, UTI is associated with underlying congenital anomalies such as posterior urethral valves, PUJ obstruction, vesicoureteral reflux (VUR), bladder diverticuli or ureteroceles etc.

Q. How does the child present?

A. The clinical manifestations of UTI are non-specific and general. At younger age i.e. in new-borns and infants- fever, failure to thrive, vomiting or diarrhoea, convulsions, jaundice predominate, hence UTI can be missed at the early stage, when it is important to diagnose.

In older children above the age of 4-5 years, UTI manifests with fever, pain in abdomen especially loin pain, vomiting with urinary symptoms such as frequency, urgency, dysuria, painful micturition and foul smelling urine. The fever can be associated with chills and recurs frequently. When the UTI is recurrent there is failure to thrive, anaemia, listlessness and general malaise

Q. How do you diagnose UTI?

A. The gold standard for diagnosis of UTI is: Urine culture, colony count and antibiotic sensitivity report in a clinical setting of UTI. The collection of urine under sterile conditions is an important point to remember. In very young infants, suprapubic bladder aspiration and in females or infants, use of urinary collection bags may be needed.

In older children midstream clean catch collection of urine in a sterile container and sending it within an hour or two to the lab are important points to get an accurate diagnosis of UTI. Presence of pus cells (more than 10/ HPF in males and 25/hpf in female children) and gram staining of fresh sample of urine for gm-ve bacilli support the diagnosis of UTI. 50% of cases of UTI may not have pyuria.

There are chemical tests like a) leukocyte esterase test and b) nitrite test, which can be used as screening test for UTI but the gold standard, is urine culture even in these children.

Q. How do you investigate a child with UTI?

A. Since there is a high incidence of congenital obstructive and non obstructive malformations of kidney and urinary tract in 50-75% of infants with UTI, early diagnosis of these malformations is useful in preventing permanent kidney damage which occurs if congenital defects + UTI combine. Hence every child with UTI below the age of 3 years should be investigated as follows:

1) USG of kidneys, pelvicalyceal system, ureter and urinary bladder to detect dilatation (hydronephrosis, hydroureter, distended bladder and residual urine) which denotes either obstruction in subvesical region or VU reflux.

To detect the site of obstruction (like PU valves) or reflux, MCU should be performed in every child below the age of 2-3 years with UTI. It is done 3 - 6 weeks after the acute episode is over. Above the age of 3 years, MCU is indicated in those children with abnormal USG findings or renal scars detected on Tc DMSA renal scan which is the 3rd imaging test in a child with UTI. DMSA renal scan is ideally done 3 - 6 months after the acute episode is over. The aim of Tc99 DMSA renal scan is to detect acute infection of kidney and subsequently after 3-6 months of pyelonephritis to detect permanent renal scars.