Urine acidity can influence risk of urinary tract infections

A new US study indicates why some people are more susceptible to urinary tract infections (UTIs) and some less. One of the reasons appears to be the acidity of urine as well as the presence of certain small molecules. The findings have been published in the "Journal of Biological Chemistry".

For the study, the research team at Washington University in St. Louis, Missouri, cultured E. coli in urine samples from healthy volunteers and observed bacterial growth, noting major differences in how well individual urine samples could limit or allow bacterial growth.

The urine samples that prevented bacterial growth supported more activity of the protein siderocalin, which the body makes naturally in response to infection and which helps the body fight infection by depriving bacteria of the iron necessary for bacterial growth. Further analysis showed that the effectiveness of siderocalin was linked to how acidic or basic the urine was - the more basic the urine was, the more effective siderocalin performed. The researchers also showed that they could encourage or discourage bacterial growth in urine simply by adjusting the pH.

Furthermore, the researchers determined that the presence of small metabolites called aromatics, which vary depending on a person's diet, also contributed to variations in bacterial growth. Samples that restricted bacterial growth had more aromatic compounds. The authors suspect that at least some of these aromatics are good iron binders. Dietary interventions paired with other therapies may therefore could provide a means of treating UTIs, the researchers concluded.

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