How Children Get Urinary Tract Infections

August 30, 2008

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How Children Get Urinary Tract Infections

by Lynn Cates, M.D., F.A.A.P.
reviewed by Laura Jana, M.D., F.A.A.P.

When a parent hears that his child has a urinary tract infection (UTI), he often wonders just how she got it and if there was anything he could have done to avoid it. There are several factors that alone, or in combination, may have contributed to the infection. Some can be prevented, but others cannot. Some of the things that can lead to urinary tract infections are as follows:

Inadequate cleansing of the genital area
Although it can be a major challenge to clean your child's genital area thoroughly-yet gently--inadequate cleansing of this area may make a child more likely to get an infection of the urethra (urethritis) and/or bladder. Bacteria can thrive in the warm moist areas of a girl's genital region and in the area under the foreskin in an uncircumcised boy. Since the urethra (the tube that leads from the outside into the bladder) is short and very close to the rectum in girls, bacteria don't have very far to go to get into the bladder. Similarly, bacteria under the foreskin of boys are right at the entrance to the urethra.

Irritants to the genital area
Just as it is important to keep your child's genital area clean, it is crucial that you don't go about the cleansing too vigorously. If your child's genitalia--particularly her urethra--is irritated or inflamed, more bacteria may be able to enter her bladder. The reason is twofold: First, inflammation provides a better environment for bacteria to multiply, and, second, it may cause the urethral opening to enlarge, permitting bacteria better access to the bladder. Therefore, it is helpful to avoid anything that might irritate her genital region, such as soaps (especially those with perfumes and dyes), shampoos (shampoo hair at the end of a bath, or better yet in the shower), and bubble bath. Also avoid rough toilet tissue or vigorous wiping. Gentle cleansing with warm water alone is sufficient to keep the genital area clean in young children.

Congenital malformations of the urinary tract
Usually few, if any, bacteria are able to get into the urinary tract. Those few that do get in are flushed right back out in the urine. Normal urinary tract anatomy helps keep urine flowing in only one direction-from the kidneys to the bladder and then to the outside of the body. Abnormal blockages or swellings in urinary tract structures prevent urine from flowing normally, and allow it build up and stagnate. This provides an excellent place for bacteria to multiply and cause infection. Children can either be born with abnormalities in the structures of the urinary tract, and or - less commonly - they can develop them as a result of environmental factors such as infections or trauma. Ordinarily these abnormalities can be repaired surgically by experienced urologists. The most common abnormalities are the following:

Vesicoureteral reflux (VUR or reflux). Reflux is the backward flow of urine from the bladder to the kidneys. When urine travels in the wrong direction, it can carry bacteria to the kidneys and help increase the risk of upper urinary tract infections. This condition is seen in both boys and girls, and is found most often--and its most severe form--in children under two years of age (especially in the first year of life). Some children are born with reflux, and others develop reflux temporarily while they have an active urinary tract infection. When reflux is detected on special imaging studies of the urinary tract, it is graded from I through V based on how much swelling and distortion of the anatomy is in the tubes going to the kidney (the ureters) and the area at the top of the ureters adjacent to the kidneys (the renal pelvis or collecting system). The mildest (Grade I) is simple reflux of urine from the bladder without any dilatation of the ureters, while the most severe (Grade V) is massive reflux of urine all the way up to the kidney with gross distortion of the ureters and entire collecting system. Children with higher grades of reflux that last a long time are more likely to develop permanent scarring of the kidneys than children with mild, temporary reflux. Up to half of children with bacteria in their urine will have at least transient reflux.

Posterior urethral valves are small flaps of tissue that can partially block the flow of urine from the bladder to the outside (urethra) in boys. When there is a blockage, bacteria can multiply in the bladder and cause infection. In more severe cases, the blockage causes back pressure resulting in reflux of urine all the way back up to the kidneys (see reflux above). Boys with posterior urethral valves may have a weak urine stream (e.g., they may not be able to spray you in the face when you are trying to change their diaper). This condition can be repaired by an experienced urologist and involves a minor surgical procedure to open up the valves.

Exposure to large numbers of bacteria
A common cause of urethritis and bladder infections in girls is bubble baths. Liquid bubble bath solutions are not only irritating, they also provide excellent places for bacteria to multiply so when little girls soak in the tub, the bacteria enter the bladder through the urethra and cause infection. If your daughter doesn't have a problem with urinary tract infections and she likes to take bubble baths, her risk can be decreased by limiting her bubble baths to only 15 to 20 minutes, followed by careful rinsing of her genitalia in clear water.

Bloodstream infections
Sometimes bacteria get into the kidneys and urine through the bloodstream (or sepsis) from elsewhere in the body. This kind of infection is more common in newborn infants than older children, and in children with decreased immunity (e.g., those with HIV/AIDS or cancer).


RELATED INFORMATION

			Circumcision: An Overview
			Urinary Tract Problems

Created February 28, 2001
Reviewed March 12, 2001

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