Maggots under microscope for superbug-killing secretions

[October 18, 2016]  By Matthew Stock

Maggots could help tackle the looming crisis of antibacterial resistance, according to researchers from Swansea University, who found that certain molecules in the secretions of green bottle fly maggots are highly effective at killing some species of bacteria.

The wound cleaning ability exhibited by these insects has a long history in medicine with battlefield surgeons in particular using them to help clean up infected and dead flesh. But it's the minute secretions that these maggots leave behind that could hold the key for viable new medicines to help combat so-called superbugs like methicillin-resistant Staphylococcus aureus (MRSA).

"We knew, anecdotally and from past studies, that maggots were working to kill bacterial infections in wounds," explained Dr Yamni Nigam, lead researcher of the Swansea Maggot Research group.

"We decided to look at the excretions and the secretions of maggots; we collected those and we examined them for various activities including antibacterial to try and see which species of bacteria they could kill. To our surprise we found that we had excellent antibacterial activity in certain fractions, in certain samples of maggot secretions."

At the labs in Swansea University, Nigam is using maggot larvae of the common green bottle fly, Lucilia sericata. To collect their secretions, several hundred maggots are placed in a container of sterile water and left overnight. When the maggots are filtered out from the water the following day, the resulting liquid is of a greater volume than what was initially added. Nigam said this pungent mixture holds the molecules they're after.

"Our current aim is to extract the secretion and to try and isolate the molecule and identify exactly what it's made up of," she said. "Once we know the structure we are planning to synthesize (the molecule) artificially and then test it against known species of even resistant bacteria that we know actual maggot secretions are killing. So that's a new hope for a novel new antibiotic that we're hoping to one day find from the maggot secretions."

Nigam added that they have trademarked this molecule, and called it Seraticin.

Previous clinical trials have examined maggots' efficacy in speeding up cleaning and healing of infected wounds. In 2009, a team from the University of York recruited 267 patients with venous leg ulcers and treated them either with maggots or hydrogel, a standard wound-cleaning product. They found a significant benefit of using maggots in terms of wound debridement and clearing of dead tissue, but could not show any significant difference in healing outcomes or cost.

"In terms of whether they have any role in promoting good cells... we've found quite a lot of molecules that appear to be quite pivotal in the wound healing process," said Nigam, adding that more clinical trials are needed to determine if these molecules do play a significant role in the promotion of healing.

She added that Swansea University will soon embark on a major collaboration with a leading British university to take the research to the next level, hastening the structural elucidation and synthesis of Seraticin.

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