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}}</ref> Although ''E. coli'' is one of the most common bacteria on the surface of human skin, strains found in hospitals tend to be particularly virulent. ''E. coli'' that live in the intestinal tract cause urinary tract infections when allowed to get into the sterile urinary tract. Whether intact or circumcised, baby boys sitting in poopy diapers allows ''E. coli'' an opportunity to enter the urinary tract. And, of course, fiddling with the foreskin and introducing bacteria foreign to the baby's body or his urinary tract can cause UTI, too. The tight [[foreskin]] of the infant boy acts as a sphincter to allow [[urine ]] to flow out, but prevents contaminants and pathogens from coming in.<ref name="Fleiss 1998">{{REFjournal

}}</ref> The term ''vesicoureteral [ureterovesical] reflux'' refers to backflow of [[urine ]] from the bladder to the ureters or kidneys. ''Ureteropelvic obstruction'' is a blockage or narrowing of part of the urinary tract. These kinds of congenital abnormalities are known to be the root cause of most UTI, as they may allow pathogens to flow upstream within the urinary tract.

As circumcision necessitates [[forced retraction]] of the foreskin, additionally creating an open wound that is vulnerable to additional infection, parents are advised against circumcision.<ref name="Outerbridge 1998"/> These functions suggest that the intact prepuce may offer protection against UTI if undisturbed. The [[foreskin]] provides two physical lines of defense in the intact male child, which are removed in circumcision: the preputial sphincter, which closes when a boy is not urinating, and a protected meatus (urinary opening), which is often inflamed and open in circumcised boys.<ref name="Cunningham 1986"/> Recently, Fleiss et al. (1998) reviewed the immunological functions of the prepuce. In addition, the sub-preputial moisture contains lysosyme, which has an anti-bacterial action.<ref name="Fleiss 1998"/> Oligosaccharides excreted in the [[urine ]] of breastfed babies prevent adhesion of pathogens to uroepithelial tissue.<ref name="Marild 1990"/>

}}</ref> Based on their observations of these old charts, they reported that Intact boys had a slightly higher rate of bacteriuria (bacteria in the [[urine]]) than circumcised boys during their first year of life, leading to the sensational statistic that circumcision resulted in a "ten to hundred times decrease in urinary tract infections in circumcised boys."

* The Wiswell studies considered bacteriuria as diagnostic of UTI. However, a positive [[urine ]] culture alone is not necessarily indicative of symptomatic UTI requiring treatment.<ref>{{REFjournal

}}</ref> There is a significant false-positive rate in diagnosing UTI when [[urine ]] cultures alone are used.<ref name="Mueller 1997"/><ref name="Saez-Llorens 1989"/> This criticism was addressed to some extent in Wiswell's second review.<ref name="Wiswell 1986"/>