Delegates at a conference in Chicago recently learned how maggots could one day heal stubborn wounds in diabetic patients who are otherwise facing lower limb amputation. In a small trial whose results have not yet been reported for peer review, 27 of the 37 patients who underwent the “biosurgery” given by Dr Lawrence Eron of the University of Hawaii in Honolulu using sterile larvae of the green blow-fly (Lucilia sericata), had successful outcomes.

Eron reported his findings orally at an Interscience Conference on Anti-Microbial Agents and Chemotherapy in Chicago last week.

Experts say the method now needs to undergo clinical trials to establish its effectiveness and safety. But Eron seems confident it will pass the test, and moreover, prove to be much cheaper than conventional methods.

He said a simple uninfected diabetic foot ulcer can cost $10,000 to treat, and if that fails and the foot has to be amputated, you can add another $65,000 to the bill.

On the other hand, the “maggots” cost about $100 for 200, which means an average five-cycle treatment would cost about $500.

“There’s no question that these little critters are able to debride tissue very efficiently,” Eron told MedPage Today.

All 37 patients in the group Eron treated had a type of artery disease that results in poor circulation in the limbs. They all had stubborn lesions, some up to five years old.

The usual procedure is debridement, where doctors remove infected or dead tissue with scalpels or enzymes, but this can sometimes fail.

The maggots only eat “devitalized” tissue, and ignore the living tissue, said Eron. This means they are great for cleaning up diabetic lesions that don’t respond to standard treatment.

For the study, he and his team put 50 to 100 larvae on each wound and left them there for two days, then took them away and replaced them with new ones. They did this about five times per wound.

Eron told Reuters news agency that they sealed them so they could not escape.

Maggots produce chemicals that make the dead tissue into a liquid so they can suck it up and digest it. They also secrete chemicals that stimulate the development of granulation tissue, a type of tissue that forms when wounds heal.

For the study, Eron defined “success” as complete removal of devitalized tissue, formation of robust granulation tissue, and at least 50% closure of the wound.

Among the 37 patients were 4 cases of gangrene, 18 abscesses, six infected ulcers, and nine cases of osteomyelitis, a type of bone infection.

Five of the wounds were infected with MRSA, but they healed successfully after the maggot treatment. All 10 wounds infected with group B streptococci also healed, but only six of nine wounds infected with MSSA healed, said Eron.

He added that the 10 patients whose maggot therapy failed had excessive inflammation around the wounds, or their wounds were bleeding, or they had severe peripheral vascular disease, or they had fistulae from infected bones that closed after single treatment.

Written by Catharine Paddock PhD