Inhibitors of bacterial growth in urine: what is the role of betaines?

It has long been recognised that some individuals produce urine that is inh ibitory to uropathogens. This may be partly explained by inhibitors. Severa l inhibitors have been identified in urine including urea and organic acids . Bacteria adapt to high osmolarity by activating osmoregulated betaine por ters and accumulating organic osmolytes intracellularly. The preferred subs trate is glycine betaine, which is present in urine, and promotes rapid gro wth by balancing osmotic forces and stabilising macromolecular structures a gainst the toxicity of urea and low pH. Other dietary betaines such as trig onelline may also be taken but enhance urea toxicity. The importance of suc h compounds in vivo is unknown. (C) 1999 Elsevier Science B.V. All rights r eserved.