A world without antibiotics would drive us back to the Dark Ages. When we run out of bacteria-fighting drugs—a scenario that scientists say might come sooner than later—major surgery will be too risky to perform, and food will get more expensive. Even our wound treatment could get medieval, but with a high-tech twist. One scientist is making genetically-modified maggots that pump out human growth factor, which could help treat and sterilize open wounds when antibiotics don't work anymore.
Max Scott, a professor of entomology at North Carolina State University, developed the wound-cleaning maggot as a side project, and received no funding to do his proof-of-concept work. "We had the technology to engineer blowflies, and realized we could apply it to a closely related species, for cleaning wounds," he told me.
Scott's lab focuses on creating engineered strains of the Australian sheep blowfly and the New World screwworm, two livestock pests. For decades, these bugs have been controlled by blasting them with radiation to sterilize them, then releasing them into the wild to mate with others. But healthy bugs don't really like to mate with sickly, irradiated ones. And anyway, Scott says his GM technique is a lot more efficient.
"We're modifying [insect] strains so they carry genes that are lethal to female flies, but not male," he said. The males still mate with female bugs, but produce no offspring—a similar method to what's being done at Oxitec, with mosquitoes, to put a stop to the transmission of Zika and other mosquito-borne viruses.
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The green bottle fly larvae is already used in FDA-approved "maggot debridement therapy," in which maggots are applied to non-healing wounds, like diabetic foot ulcers, which can lead to gangrene. It's a time-honoured technique, and seems to work in a few different ways. Maggots munch away dead tissue, but also "change the pH of the wound," Scott said, by secreting ammonia and making it more alkaline, and thus less friendly to invasive bacteria. "They also secrete antimicrobial peptides," he said. The bugs can be effective against MRSA, for example, a particularly fearsome drug-resistant bug.
These GM maggots are even better, because they also pump out something called human platelet-derived growth factor-BB, which stimulates cell growth and survival.
Scott recognizes that maggots aren't everyone's cup of tea. But some people don't have other options, he said. There are suppliers of prescription-only medical maggots in the US, like Monarch Labs, which markets a few different "maggot dressings" (one with the jaunty name "Le Flap duJour"). Some companies sell them in "porous bags," he said, which are placed over the wound, so that nobody has to deal directly with bugs.
And patients can be surprisingly receptive, said Scott, who hopes to do a study of his GM maggots in lab animals next, and eventually move to humans. "My old neighbour was a retired nurse. She said that patients were quite happy to try it, if it would save them from amputation," he said. "It was a lot of the nurses that had a hard time."