Insect antibiotics Resistance ...( affected when bacteria experience nutr...)

"It is a whole different mechanism by which to kill bacteria, and one that we still have yet to completely figure out," said Axelsen. "How Cecropin A turns these genes on and, indeed, how it gets inside E. coli in the first place, is still something of a mystery."

Despite years of research, there remains much to know about the antibiotics produced by insects. Cecropin A was discovered in the Cecropia moth, also known as the silkworm moth, the largest moth in North America. Since insects do not have an immune system as humans do, they rely on polypeptide antibiotics like Cecropin A to fight off infections. These proteins are highly selective they readily kill bacteria, but are harmless to human and other animal cells. Moreover, bacteria that are susceptible initially stay susceptible - researchers have not seen bacteria develop resistance to their action. For this reason, these antibiotics offer a potentially invaluable model for new therapeutic agents.

"We're engaged in an arms race against infectious bacteria. With each new antibiotic, bacteria have found a way to evolve resistance primarily by slightly altering cellular enzymes," said Axelsen. "Bacteria may be unable to alter their genetic machinery, and this may explain why strains of bacteria resistant to Cecropin A do not arise."

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Contact: Greg Lester
lesterg@uphs.upenn.edu
215-349-5658
University of Pennsylvania School of Medicine
6-Feb-2003