Cornering cholera

A new treatment for the age-old scourge of cholera and perhaps a whole new type of antibiotic medicine may emerge from chemicals discovered in an Australian seaweed, new research results suggest.

Researchers at the University of New South Wales have found that furanones - isolated from the seaweed Delisea pulchra - can prevent the bacteria that cause cholera from switching on their disease-causing mechanisms.

It seems likely that furanones can have the same effect on many other bacteria, such as those that cause food poisoning and cystic fibrosis-related infections. Furanones do not kill such microbes but simply 'jam' their ability to send signals to each other. This means as well that their use is far less likely to create the drug-resistance problems that plague current anti-microbial treatments.

The team has found that when the bacteria that cause cholera - Vibrio cholerae - are exposed to furanones, they cannot switch on their so-called virulence factors associated with infection and the development of the disease.

The new experiments suggest that furanones may prevent cholera bacteria from escaping the host immune response and secreting toxins to weaken their host. Many bacteria rely on a signalling system known as quorum sensing to detect when enough of their own kind is present and then change their behaviour and attach themselves to a surface on a host or in the environment. The seaweed, a red algal species found at a UNSW marine research site in Sydney's Botany Bay, produces the compounds to prevent bacteria from forming biofils on its leaves.

The discovery - so far only established in laboratory tests - is now being tested further in trials involving mice and tissue cultures.