Protein-Rich Frog Foam For Antibiotic Drug Delivery

Sometimes innovations in drug delivery come from an unlikely source. Scientists from the University of Strathclyde in Scotland, have demonstrated the effectiveness of a proteinaceous foam made by Tungara frogs, as an antibiotic delivery system for infection prevention. The details of their research were presented yesterday at the Microbiology Society’s Annual Conference in Liverpool.

Trinidadian Tungara frogs (Engystomops pustulosus) produce a novel protein substance when mating, which the frogs then whip into a foam with their hind legs. The female frogs lay their eggs in the foam nests, which act as protective barrier against predators, environmental stresses, and microbial pathogens.

In their analysis of the foam, the researchers found that the substance was able to carry a drug load in a stable manner, and release the pharmaceutical at a predictable rate. Using model dyes, the team demonstrated that the foam could steadily release the load over a period of 72 to 168 hours.

What’s more, when the researchers loaded vancomycin – an antibiotic – into the foam, it was able to prevent Staphylococcus aureus bacterial growth for 48 hours. Importantly, the foam was found to be non-toxic when exposed to skin cells for a 24 hour period – a result that could make the foam suitable for direct-to-skin application.

“Foams are usually very short-lived so they’re not considered for long-term drug release, even though they have great potential for topical treatments,” said Sarah Brozio, a researcher on the study from the University of Strathclyde. “This foam comes from a tiny frog and yet offers us a whole new approach that could prevent wound infections, and with increasing antibiotic resistance it’s important that all new tactics are explored.”

According to Brozio and her colleagues, the foam could be used for targeted drug delivery on specific areas of the body. In particular, patients with severe burns could benefit from the foam’s long-lasting release of antibiotics targeted toward the burn sight.

The researchers have already engineered E. coli to produce a recombinant version of the foam’s proteins, including Ranaspumin-2. They are also working towards making a fully synthetic version of the frog foam using an E. coli expression system.