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Thursday, 2 November, 2000, 00:01 GMT
How bugs could fight bugs
The breakthrough could lead to new treatments
Insects' natural defences against invading bacteria could give doctors another weapon against antibiotic resistance.

Bacteria which attack insects are neutralised by specialised body chemicals which knock out proteins vital to the microbes' survival.

Humans do not have this mechanism, and rely on immune system cells launching an attack on the foreign invaders.

Many bacteria are resistant to antibiotics
Current antibiotics work by killing bacteria while leaving human cells unharmed, but many strains of bacteria are rapidly becoming resistant to all but a few, powerful drugs.

Scientists from the Wistar Institute in Philadelphia, US, are now trying to harness the bacteria-killing power of the insect defence mechanism.

Their secret weapon, reported in New Scientist magazine, is a European sap-sucking insect called Pyrrhocoris apterus.

Most of the body chemicals used by the bugs could not be used in humans, as they would cause as much damage to human cells as to the bacteria.

But Dr Laszlo Otvos has managed to isolate peptides from the insect which he believes are interfering with a key mechanism keeping bacterial cells working properly.

Without these mechanisms, which help bacteria proteins do their correct tasks, the microbes will die.

Safe for humans?

And these peptides appear not to interfere with the same mechanism in human cells, so it may be safe to use in humans.

The only current limitation is that the effect has only been achieved in a few types of bacteria, and not those in which resistance is causing the biggest problems in humans, such as MRSA.

The team from Philadelphia infected mice with different types of bacteria, and found that the insect peptide protected them from bacteria such as E.coli and Salmonella.

They are hopeful that more development will lead to peptides effective against a wider range of bacteria.

And because each drug would be specific to a narrow range of bacteria, the opportunities for antibiotic resistance to develop would be less.

Professor Ian Chopra, head of the Antimicrobial Research Centre at Leeds University, said that the breakthrough represented the "beginning of a renaissance" in antibiotic invention.

He said: "It's an elegant piece of biochemistry. In the last two or three years, there has been a whole host of reports of peptides with antibiotic activity.

"This has taken a new approach, and chosen what looks like a good target."

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05 Jan 00 | Health
Bug battle enters new century
11 Oct 00 | Health
Warning over antibiotic use
17 Feb 00 | Health
NHS bugs 'kill 5,000 a year'
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