By Robert S. Boyd

For years, you've been able to walk into a drugstore or health food outlet
and buy a host of "probiotics" to treat conditions such as children's eczema
or traveler's diarrhea.
Unlike antibiotics, these self-help products don't kill germs, but they
supposedly confer health benefits, as vitamins and certain minerals do.
Existing probiotics haven't been approved by the Food and Drug
Administration or subjected to rigorous clinical trials. When tested, their
effectiveness has been mixed, medical researchers say.

Now scientists are trying to design "good bugs," novel forms of bacteria
created in the laboratory to prevent or cure specific diseases, including
HIV and cancer.

"Perhaps the only hope of winning the war against 'bad bugs' will be
achieved by recruiting 'good bugs' as our allies," said Roy Sleator in an
e-mail. He is a microbiologist at University College in Cork, Ireland, and
editor of a forthcoming scientific journal called "Bioengineered Bugs."

He said his laboratory had engineered a new generation of "designer
probiotics" tailored to target certain disease-causing microbes or toxins.
His "good bugs" mimic receptor proteins on harmful bacteria and block their
ability to infect healthy cells.

"Designer probiotics bind to bacterial toxins in the gut ... thereby
preventing disease," Adrienne and James Paton, researchers at the University
of Adelaide, Australia, reported in the journal Nature Microbiology.

In a e-mail, James Paton said his lab had designed a probiotic that works
against E. coli O157, a notorious microbe that has caused serious, sometimes
fatal intestinal disease outbreaks.

The need for more effective antibiotics is widely recognized because of an
alarming increase in the ability of bacteria to resist standard medicines. A
special concern is the virulent MRSA ? methicillin-resistant Staphylococcus
aureus ? a bacterium that infects and sometimes kills hospital patients.

"It is becoming increasingly apparent that alternative approaches to
conventional antibiotic therapy are required to control infectious diseases
in humans and animals in the 21st century," Paton said.

"Increasing incidence of antibiotic resistance ... has forced clinical
research to explore alternative therapeutic and prophylactic avenues,"
Sleator wrote in a British microbiological journal. "Probiotics are finally
beginning to represent a viable alternative to traditional drug-based
therapy."

Sleator said his lab had genetically engineered a harmless strain of E. coli
to secrete a substance that might be used against HIV. He's also working on
probiotics that might help prevent or reduce recurrence of certain cancers.

Researchers caution that designer probiotics are still in development, need
further tests and government approval and have a number of shortcomings.
www.checkbiotech.org