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Our recent study on male neonatal circumcision and subsequent risk of urinary tract infection (UTI) suggested a three- to fourfold relative risk of hospitalization for UTI. This was similar to the recent 4.8-fold risk reported by Craig et al (1) but lower than earlier estimates reported by others (2–5). Although it also supports the notion that circumcision may protect boys from UTI, it suggests that the magnitude of this effect may be less than previously estimated in the United States. While this difference in the estimate may be due in part to the risk of UTI being different in various study populations, other factors such as differences in identification of UTIs that may explain the difference need further research.
Because the focus of our study was to examine the relationship between male neonatal circumcision and UTI, female infants were excluded. An inspection of Ontario hospital discharge data collected by the Canadian Institute for Health Information (CIHI) for fiscal 1993 showed the rate of UTI hospitalization among female infants under one year of age was 0.65%. This was slightly higher than the 0.49% reported by Wiswell et al (6) based on 1980 to 1984 data. The corresponding rates for male infants were 0.44% and 0.30% in Ontario and United States, respectively (6). We agree with Dr Outerbridge that infant UTI is not limited to boys; therefore, the overall discussion of prevention and management of UTI should not be sex specific even though specific studies, such as ours, need to concentrate on male infants. Because most infants with UTI never develop serious outcomes and only a small fraction of all children will develop a UTI, efforts in primary prevention may have a low yield compared with primary prevention for other diseases.
However, we recognize that despite the low prevalence of UTI resulting in hospitalization, among young infants at increased risk of recurrent UTI the potential risks, such as renal scarring and damage, etc, could be serious. In the first year of life, acute pyelonephritis often leads to significant renal damage that may progress to end-stage renal disease during adolescence. Thus, it may be more reasonable to target prevention and treatment strategies in young children at increased risk for recurrent UTI and those at higher risk for renal scarring. Alternatively, primary prevention manoeuvres for the whole population could be justified if they were sufficiently simple, noninvasive, inexpensive and scientifically demonstrated to be cost-effective.
While breastfeeding is beneficial, its role in preventing a UTI and in particular the prevention of recurrent UTI is uncertain. Pisacane et al’s (7,8) case-control study used single hospital admission data which suggested that breastfeeding has a protective effect in urinary tract infection. Because breastfeeding is associated with factors such as birth weight, the mother’s age, level of education, parental attitudes, style or personality, etc, it is important to control for these factors that may confound the association. The results reported by Pisacane et al (7,8) are suggestive of a causal relationship, but are not proof of one. A well-defined birth cohort study is necessary to confirm the reported findings. A recent article by James-Ellison et al (9) showed that the secretory immunoglobulin (Ig) A and IgA levels were higher among infants who were breastfed, but found no significant difference in secretory IgA, IgA and free secretory component in the urine of children with recurrent UTI compared with controls. As well, Marild et al (10) also suggested a prospective study is needed to elucidate the possible role of the anti-adhesive effects of breast milk on the occurrence of UTI. There are unanswered questions concerning the role of breastfeeding in relation to UTI, and further research is required before breastfeeding can be considered as an effective alternative measure in preventing UTI in infants.
In the end, we recognize that there are other advantages of breastfeeding. While there may be inadequate scientific evidence at this point to recommend it as a specific primary prevention manoeuvre for UTIs, there are compelling reasons to recommend it for child health based on other reasons.