IS THE ABILITY OF URINARY-TRACT PATHOGENS TO ACCUMULATE GLYCINE BETAINE A FACTOR IN THE VIRULENCE OF PATHOGENIC STRAINS

The regulation of intracellular concentrations of organic solutes, inc luding glycine betaine, is an important adaptive response to osmotic s tress for Escherichia coli. The clinical significance of glycine betai ne to uropathogens is not clear. Clinical isolates of E. coli, Klebsie lla pneumoniae, Enterobacter species, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, S. saprophyticus, and Enterococcus f aecalis accumulated glycine betaine from hyperosmotic media. The addit ion of glycine betaine to hyperosmotic minimal medium accelerated the growth rates of all species tested except P. mirabilis. However, when clinical strains of E. coli were transferred from urine with low osmol ality to hyperosmotic urine, there was no slowing of the growth rate. There was no difference in growth rates of E. coli isolates from acute pyelonephritis, cystitis, and asymptomatic bacteriuria nor from fecal isolates. The ability to accumulate osmolytes, although it may be a f actor in the adaptation to hypertonic environments, was not related to virulence.