The Truth About... Gangrene

IT IS a truth universally acknowledged in science that natural poisons are infinitely nastier than anything synthesised by man. Nothing illustrates this more clearly than the toxin produced by Clostridium perfringens, a ubiquitous bacterium that causes gas gangrene, a severe infection of open wounds that usually results in death or amputation.

The Clostridium family of bacteria is responsible for tetanus, botulism and other disagreeable types of food poisoning. When C perfringens - which exists in soil, water and even tucked safely away inside our own intestines - infects an open wound, it can spread rapidly through the flesh.

If it reaches the bone, then nothing can be done short of amputation. If left untreated gas gangrene causes severe blood poisoning, kidney failure, coma and death.

Gas gangrene derives its name from the pockets of gas that accumulate in infected tissue as a result of bacterial action. It is a common illness of the battlefield, where dirt and open wounds provide the perfect opportunity for the bacteria to enter the body. Hundreds of victims of the tidal wave disaster in Papua New Guinea succumbed to gas gangrene. Many had to have limbs removed.

About 100 people a year develop gangrene in Britain, often from complications after traffic accidents.

There is no cure for gas gangrene, which can overwhelm a person within hours. Antibiotics work only if they are taken long before infection takes root. Once infected, the diseased tissue turns black; death can occur within six hours.

Military authorities have taken a keen interest in the toxin produced by the bacteria because of its potential for use as a weapon of biological warfare. Saddam Hussein is believed to have purchased two tons of the bacteria, apparently in order to produce enough toxin for use in missile warheads. Contaminated shrapnel would inoculate the bacterial toxin directly into the flesh of bomb victims.

Studies of C perfringens began in 1891 and scientists quickly found that the toxin attacks the molecules of the protective cell membrane. After a century of research, scientists have now found a chink in gas gangrene's armour that may eventually lead to the development of vaccines or drugs.

Professor David Moss, Dr Ajit Basak and Dr Claire Naylor, of Birkbeck College, London, have worked out the three-dimensional structure of the bacterium's deadly toxin with the help of scientists from Porton Down, the Ministry of Defence's chemical weapons research facility. They believe they have found the "active site" that is responsible for binding to human cells and thereby triggering the cascade of chemical reactions that lead to the rapid destruction of cell membranes.

Dr Basak said: "We want to design something that will bind to the active sites on the toxin molecule to stop it working. Identifying the three- dimensional structure is the first step in the development of drugs to target the toxin and neutralise its effects."

Steve Connor

Science Editor