Interactions In Urinary Tract Infections

The literature reports that approximately 50% of children with a documented urinary tract infection (UTI) will have demonstrable pathology.

E. coli bacteria are the main cause of infections in the human urinary tract. They represent opportunistic infections arising from the patient’s own bacterial personal flora.

The infecting strains fall into two groups: those causing symptoms and those that persist as asymptomatic bacteriuria.

P FIMBRIAE

E. coli have specific somatic, or cell wall (0) antigens by which they can be grouped. These antigens are sugar side chains attached to the cell wall of the organism. E. coli with 0 groups 1, 2, 4, 6, 7, 8, 16, 18 and 25 are found more frequently in patients with pyelonephritis.

The vast majority of urinary tract infections occur through the ascending route. The fimbriae on the surface of the E. coli enable the bacteria to bind to specific carbohydrate receptors on the surface of uroepithelial cells. P fimbria is a hemagglutinin which recognizes a P blood group antigen of glycolipids found on uroepithelial cells. P fimbriae are commonly found on bacteria, causing pyelonephritis but not cystitis or asymptomatic bacteria.

Analysis of P blood group distribution in relation to the fecal carriage of P fimbriated E. coli strains show that the carriage of P fimbriated strains is increased in individuals of the P-1 blood group. P-1 individuals have previously been shown to run an 11-fold increased relative risk of recurrent pyelonephritis compared to the population at large. One mechanism explaining this increased carriage is adherence. Vaginal, periurethral, urinary tract and buccal epithelial cells from UTI-prone girls and women have an increased receptivity for adhering uropathogenic E. coli compared to cells of healthy controls.

Uropathogenic E. coli express a variety of adhesins, including P and type I fimbriae.

P fimbriae can trigger release of interleukins and C reactive protein and bring about reduced renal concentrating capacity in patients with a UTI in addition to causing inflammation and scarring.

HEMOLYSIN

Hemolysin has been regarded as a virulence factor for the urinary tract and has the ability to lyse red cells, white cells and renal tubular cells. Hemolysin is common in UTI strains.

In summary, infections are possible when several conditions coexist, such as the finding of specific receptor sites on the urinary tract cells such as glycolipids and mannose, for certain uropathogens such as E. coli and enterococcus faecalis, and factors such as lipopolysaccharides (0 antigens), capsular antigens (K), adhesins (particularly type P and I fimbriae) and hemolysin.

DMSA scans are highly reliable for the detection and localization of acute pyelonephritis.

The administration of antibiotics is still the most effective way to eradicate uncomplicated infections. However, drug resistance has induced people to look at the possibility of inoculating problem patients with avirulent E. coli and other types of noninfectious organisms such as lactobacilli.

The creation of a genital or external urethral flora dominated by selected lactobacilli, which can adhere to the patient’s cells and therefore interfere with attachment and growth of pathogens and consequently prevent severe urinary tract infections, is being investigated.

All bona fide UTIs need pediatric urological investigation, and urethral dilations are never performed to treat UTIs in girls.

Antibiotic Prophylaxis

Many children will be treated with long-term, low dose antibiotics and periodic monitoring to lessen the chance of symptomatic UTIs and kidney damage. Nearly all cases of reflux and most cases with hydronephrosis will be managed in this way. Some children who get recurrent UTIs without obvious cause after x-ray studies will also be treated in this way for a year or more. Long-term, low dose antibiotics do not cause immune or resistance problems.