Scientists found significant differences in two bacterial organisms' use of a gene linked to processes that govern a form of antibiotic resistance. The distinction alters the bacteria's "lifestyles," or their ability to survive in different environments.

Researchers say the finding shows that understanding such changes will likely help development of new treatments for disease-causing microorganisms.

"These differences in gene usage are harder to look for, but we're not going to understand these organisms fully unless we take into account this other dimension," says senior investigator Eduardo Groisman, Ph.D., professor of molecular microbiology and Howard Hughes Medical Institute investigator.

The study appears the week of Nov. 29 in the online edition of the Proceedings of the National Academy of Sciences and in print on Dec. 7.

One of the bacteria studied, Salmonella enterica, is a leading cause of food poisoning and illness related to animal husbandry. The other, Escherichia coli, can cause illness but more typically plays a beneficial role in the human digestive system.

The two are closely related genetically. Less than 20 percent of E. coli's genes are not found in Salmonella and just over 25 percent of Salmonella's genes lack counterparts in E. coli.

Groisman's research had previously focused on how differences in gene content made Salmonella a persistent source of illness. He identified several areas in the bacteria's DNA known as "pathogenicity islands" -- clusters of genes unique to Salmonella that help it cause illness.

When complete gene maps for both bacteria became available in recent years, his interests expanded to understanding how the bacteria might use identical genes differently.

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Contact: Michael Purdy
purdym@wustl.edu
314-286-0122
Washington University School of Medicine
29-Nov-2004