Sea sponge-derived compound could unlock MRSA resistance

A compound derived from this deep-water marine sponge could lead to an alternative means to attack the antibiotic-resistant bacterium, MRSA. Image: Florida Atlantic University's Harbor Branch Oceanographic Institute

MRSA has outfoxed every beta-lactam antibiotic, including methicillin, penicillin and amoxicillin. But scientists at Florida Atlantic University have found that a compound extracted from a marine sponge has an antibacterial effect against MRSA, highlighting a potential new angle to treat the drug-resistant bacterium.

The marine biomedical and biotechnology program at FAU’s Harbor Branch Oceanographic Institute maintains a library of marine materials that are tested against a range of diseases. Once a compound’s activity is determined, it is purified via bioassay-directed fractionation and then studied to determine how it works.

The team extracted an indole—an organic compound—from the deep-water sea sponge, that has a “broad spectrum of biological activity,” including the ability to inhibit a pancreatic cancer cell line, as well as MRSA, according to a statement. The findings are published in Marine Drugs.

The team tested the sea sponge-derived compound, dubbed “dragmacidin G,” in a range of assays, which included one blocking the growth of MRSA. They collaborated with colleagues from the University of Central Florida to also test how well the fractions fared in blocking the growth of a parasite that causes malaria in humans as well as the bacterium that causes tuberculosis.

They found that the enriched fraction containing dragmacidin G “showed activity” in all three assays, so they refined the compound to obtain a pure version. The team is planning further studies.

Sea sponges have been the source of inspiration for a number of promising experimental compounds. A team at Harvard reported promising results in animal studies of a sponge-derived molecule called cortistatin A, for example, which is being investigated as a treatment for acute myeloid leukemia. Merck struck a $20 million licensing deal last year with the Harvard lab working on the treatment.

While the number of invasive MRSA infections and deaths declined between 2005 and 2011, CDC estimates still peg the number of severe infections at 80,000 and deaths at more than 11,000 per year. The sea sponge-derived compound joins a class of antimicrobials that target a generic part of bacteria and antibacterial clay as new approaches to target MRSA.