Researchers find possible targets for UTI drugs

ST. LOUIS Potential targets for new drugs to fight the bacteria that cause many urinary tract infections have been identified by researchers at Washington University School of Medicine in St. Louis and the University of Washington.

Researchers found that E. coli strains culled from urine samples of women with UTI produce more yersiniabactin and salmochelin, two siderophores that help bacteria scavenge iron to support their own survival. This could help lead to the development of antibiotics that target pathogenic E. coli strains without harming beneficial bacteria in the gut. The findings appear in the Feb. 20 online issue of PLoS Pathogens.

"When we treat an infection with antibiotics, it's like dropping a bomb — nearly everything gets wiped out, regardless of whether it's helpful or harmful," stated lead author Jeff Henderson, a Washington University infectious disease specialist who treats patients with UTIs at Barnes-Jewish Hospital. "We'd like to find ways to target the bad bacteria and leave the good bacteria alone, and these siderophores are a great lead in that direction."

UTIs are one of the most common infections, causing around $1.6 billion in medical expenses every year in the United States. Half of all women will experience a UTI at some point in their lives, and recurrent UTIs affect 20% to 40% of these patients. Scientists believe 90% of all UTIs are caused by the bacterium Escherichia coli (E. coli).

The E. coli that cause UTIs may come from the human gut, where several strains of the bacteria reside. Scientists think some of those strains help their human hosts by aiding digestion and blocking other infectious organisms.

"To steal iron, siderophores have to be sent out from the cell, bind to the iron, and then be taken back into the cell," Henderson said. "If we can design an antibiotic that looks like a siderophore, we might be able to trick only disease-causing bacteria into taking up the drug while leaving other bacteria alone."