Wednesday, November 5, 2008

Robert S. Boyd

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.


© The Lexington Herald Leader 2008