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Bacterium resists body defences

University of Copenhagen researchers have found a bacterium that 'switches on' production of molecules to kill white blood cells and beat the body's immune system. The finding could help in the fight against antibiotic resistance

A common bacterium called P. Aeruginosa can shield itself against the body’s defence mechanisms, writes the US science website

A research collaboration between Danish and US researchers, including a scientist from the University of Copenhagen, has discovered how the bacterium resists attack.

Detect and destroy

The bacterium, which causes many hospital-acquired infections as well as chronic lung infections in those with pre-existing conditions such as cystic fibrosis, uses a communication system called quorum sensing (QS) to detect approaching white cells.

It forms a biofilm which spreads over the lungs like a slime. The bacterium ‘warns’ other bacteria in the biofilm. In response, the bacteria increase their production of molecules called rhamnolipids.

These sit on the surface of the biofilm to form a shield that destroys any white blood cells that encounter it.
This means that the biofilm is resistant to antibiotics and the body’s immune response.

Researchers say they must interrupt the quorum sensing to stop the building of the shield to be able to treat the bacteria.

Goal is to eradicate antibiotic resistance

Professor Michael Givskov from the University of Copenhagen, who led the study, believes there are significant clinical benefits from the finding.

»The ultimate goal is to eradicate the present day’s antibiotic-resistant bacteria that are involved in the bulk of chronic infections,« he says.

»Antibiotic resistance is one of the most serious emerging health problems in the world today. More than 70 percent of the disease-causing bacteria are resistant to at least one of the currently available antibiotics,« he adds.