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As infections become resistant to antibiotics, researchers look to natural-born killers to fight diseases

Facing a growing incidence of bacterial resistance to antibiotics, pharmaceutical companies are struggling to come up with new drugs to fight infections. The solution may lie in one of nature’s natural killers.

Phage therapy is the use of what are known as bacteriophage, viruses that are parasites of bacteria.

Phage attach to a target bacterial cell, puncturing through and entering its host. Once inside, a phage can use its new home as a replication factory before bursting and destroying the cell in search of new hosts. Phage can kill bacterial cells and disinfect contaminated food products.

Phage were discovered in the early 20th century separately by Frederick Twort and Félix d'Hérelle. D'Hérelle quickly realized the medical applications of this natural phenomenon, administering phage to patients suffering from dysentery, but his crude experiments produced varied results. While his research was pursued in the former Soviet Union, it was abandoned by the West in the 1940s in favor of newly discovered antibiotics.

Now Western companies are returning to this field of research armed with a better understanding of nature’s bacterial predators. Intralytix Inc., a phage company based in Baltimore, was established in 1998 and has been a leader in phage therapy, in particular applying this technique to decontaminate food. In 2006, it was the first company to receive approval from the Food and Drug Administration for a phage product. Phage International, Inc., of Los Altos, Calif., was founded three years ago and is conducting research in Tibilisi, Georgia, into bacteriophage therapy technologies.

“Phage are stealth killers,” said John Vazzana, president and chief executive of Intralytix. Phage even can target and kill a specific species of bacteria, even a particular strain, he added.

The Intralytix product that won FDA approval is LMP 102 and it is known to be effective in combating Listeria monocytogenes, one of the most deadly food-borne pathogens found in ready-to-eat foods.

Another food safety product developed by Intralytix and now under review by the FDA is effective against E. coli O157:H7, the strain of bacteria responsible for the recent contamination of spinach in the United States, Vazzana said.

Phage therapy does have its limitations.

According to Dr. Caroline Westwater, from the Medical University of South Carolina, the fact that the majority of phage are so highly specific about which bacterial cells they attack can pose problems.

“This means you would have to know exactly what bacteria you’re dealing with, unlike with antibiotics, where you can simply administer a broad-range drug to kill a variety of bacteria,” Westwater said.

Broad-ranging antibiotics, however, can in some cases cause more damage by destroying some of the good bacteria in the human body, Westwater said.

At Phage International, the firm’s goal “is to promote the commercial use of phage therapy in the Western world,” said David Hodges, senior vice president of Phage International. “I believe that within eight to 10 years, phage therapy will be a part of Western medicine.”

Phage International owns the Phage Therapy Center in Tbilisi, in the former Soviet Union. This facility offers treatment for people suffering from antibiotic resistant infections. The center is very precise about screening patients to ensure they are a compatible candidate for treatment.

“Patients will send a sample of the bacteria to the labs in Tblisi,” Hodges said. “We then check to see if we have a bacteriophage to attack that type of cell.”

If accepted, patients have to travel to Tbilisi for the treatment itself. “Patients will find out about us through word of mouth,” Hodges said. “They search on the Internet or find out about it from their friends.”

So is it likely that phage therapy will overtake antibiotics in popularity?

“I very much doubt that,” said Vazzana, of Intralytix. “I view them as a complement to antibiotics, not a rival.”

Email: ser2129@columbia.edu