Health: There's a bug in my bandage

You strap them on to a wound, then wait for them to eat the bacteria. Doctors swear by it. So do patients.

The new wound dressing that's just been put on to David Powell's foot appears to be moving. It's not a vigorous kind of motion, just an occasional rise and fall, almost as if a heaving mass of unseen creatures were moving about beneath that sterile white bandage.

Of course, it could all be in the mind, a trick of the imagination fuelled only a few moments ago by the sight of several dozen tiny maggots being poured on to the wound and covered with that dressing.

And, according to Dr Steve Thomas, any movement is indeed down to an overworking imagination. These are not, after all, the full-size maggots that squirm around in an angler's bait can, and anyway the 400 or so patients who have so far felt their healing touch have never had any problems. In fact, most of them report no sensation at all, not even a tickling as the grubs go about their work. Their only concern is whether maggot therapy works, and it does.

Thanks to Dr Thomas, maggots like these, the larva of the greenbottle fly, are making an unlikely comeback in modern medicine, saving limbs, fighting infection, killing bacteria and replacing antibiotics. He and his team have already supplied more than 400 other centres with 5,000 containers of maggots.

It has been known for many decades that maggots can clean wounds, but when hi-tech medicine arrived most physicians - and their patients - opted for more fastidious ways of cleaning away dead tissue and getting rid of bacteria.

However, researchers have now discovered that maggots not only clean wounds highly efficiently, they also lay down their own natural antibiotics. And with increasing concern in the medical establishment about overuse of antibiotics, and the arrival of antibiotic- resistant bugs, maggots are suddenly back in fashion as a highly effective therapy.

The maggots bred by Dr Thomas and his team at the bio-surgical research unit at the Princess of Wales Hospital, Bridgend, Glamorgan have already been successfully used on scores of patients, including a handful of people infected with the killer bacterium MRSA, which is resistant to most antibiotics.

So successful has the re-introduction of the creatures been that Dr Thomas has now produced a million of them at his laboratory in South Wales, where it all began three years ago.

"I had for a long time been interested in using maggots in wounds, but the spur was when I heard someone talking about the theoretical concept of it all," he explains. "I decided to give it a go and we set up in a tiny room in the laboratory producing a small number of flies. We refined the method of breeding them and produced sterile eggs and eventually we got the go-ahead to use them on patients."

The idea behind using maggots is quite simple - they eat bacteria. Give a maggot a meal of bugs and it will wipe the plate clean. But latest research suggests that they do much more than that, and that they work in a number of distinct ways to treat infection when they are placed on a wound.

First, bacteria act as biological chemical factories turning out potent enzymes which break down the dead tissue in the wound. Then they eat the bacteria and excrete them as dead material. Thirdly, they produce their own antibiotic and antiseptic materials in their secretions, which cleanse the area. Fourthly, they change the acidity of the wound area so that bacteria trying to colonise the wound find it difficult to grow. Growth- promoting agents are have also been detected in the secretions of the maggots, which may speed up the rate of recovery.

"We know that all sorts of things are going on," says Dr Thomas. "We know they clean the wound and that they are multi-functional, but the precise mechanism by which the maggots kill bacteria is not fully understood. We now believe that it may include the production of natural antibiotics."

In practice the maggots have been used for treating infected tissue, open wounds that may in some cases have been colonised with antibiotic- resistant bugs.

The sterile maggots, which are bred in the laboratory at Bridgend, are applied from a tube to the wound at the rate of about 10 per square centimetres. Tape applied to the surrounding healthy skin stops them from getting on to the surrounding tissue, and a mesh covering acts like a cage to keep them focused on the wound itself.

They are then left to work on the affected area for three days, after which they are removed and destroyed along with the bandages. For patients such as 37-year-old David Powell, the maggots have proved superior to other forms of treatment. He suffers from a loss of sensation in his skin. That means that injuries can occur and deteriorate without his getting the normal warning sign of pain.

"I had a piece of grit in a shoe and it caused a very serious wound before I realised what had happened," he recalls. "Because there is no sensation you don't know what is going on and it is difficult to keep track of."

"I was a bit surprised when they suggested maggots, but it has worked for me. I think it was a choice between having the maggots on or having the foot off; it was that serious. I get the dressing changed three times a week, and at the moment everything is fine."

Dr Thomas says the centre has had a number of similar cases where limbs have been saved. "It is a very successful treatment. It has often been used as a treatment of last resort, so the results are excellent given that in some cases the patients may have been a day away from losing a limb. We have shown that maggots can succeed when the chances of success are otherwise quite tiny."

He and his colleagues also believe that maggots will have a big role to play in combating antibiotic-resistance organisms such as MRSA: "We would like to see the earlier use of maggots to clean up problematic or infected wounds, and that in many cases would obviate the need for other treatment," he says.

But if maggots are to become a more general treatment, they will need to be used in routine wounds and not kept as a treatment of last resort, and that means convincing patients that they are the best option available.

Not, of course, that there is a problem in this respect. Only three patients so far are known to have turned the idea down when it has been put to them, and, as Dr Thomas points out, it's safe, highly efficient and gives excellent results. The patients feel nothing - and the bandage really doesn't move.