Researchers aim to sneak antibiotics into bacteria via naturally occurring molecule

Conjugated drug with a siderophore (blue) linked to an antibiotic (green)--Courtesy of Washington University

Researchers are attempting to develop methods of sneaking drugs past bacteria's external defense system by delivering therapies via molecules that bacteria secrete to find and obtain iron.

There are several advantages to conjugating drugs to iron-scavenging siderophores, explained Washington University chemistry professor, Timothy Wencewicz in an article in the science news service

"Today when you walk in with the symptoms of a bacterial infection," Wencewicz said, "you are treated with a broad-spectrum antibiotic because we lack the ability to identify a bacterial strain quickly. And that means every type of bacteria in your body is exposed to that antibiotic." This promotes antibacterial resistance, and may harm helpful bacteria within the body.

Wencewicz said siderophore drug delivery can overcome this problem because each species of bacteria secretes unique siderophores molecules, so conjugating antibiotics to specific types of siderophores enables targeted delivery. He added that dosage size would be reduced under this drug delivery system because the therapy would evade bacteria's external defenses.

Recently researchers at MIT revealed that they have successfully conjugated two antibiotics, ampicillin and amoxicillin, to enterobactin, a siderophore molecule. They found that the conjugated antibiotics performed better against E. coli bacteria. In some cases, the conjugates were up to 1,000 times more potent, according to an explanation published by the American Chemical Society.

Wencewicz said the new approach will require better diagnostics to identify bacterial species so that the correct siderophore can be targeted.

- read Timothy Wencewicz's overview of the delivery method
- read about the MIT research