Pathogens & People: Bacteriophage: The invisible microbe By EDWARD McSWEEGAN, For The Capital Published 07/05/09
If antibiotics disappeared tomorrow, would we be at the mercy of every stray germ? Would every cut and scratch be a potential death sentence? Would life become little more than survival of the immunologically fittest? No, but life would be different, and perhaps more complicated. Decades before Alexander Fleming picked up a moldspeckled Petri dish and discovered penicillin, other scientists had discovered a mysterious entity that also could kill bacteria. In 1896, a man named Hankin found that filtered, bacteriafree river water would kill Vibrio cholerae, the agent of cholera. Two years later, another physician named Gamaleya discovered a similar filtered water sample that would kill Bacillus subtilis, a cousin of the anthrax bacillus. It wasn't until 1917 that a FrenchCanadian microbiologist named Felix d'Herelle systemically studied this bacteriakilling phenomenon and put it to good use. D'Herelle thought the mysterious bacteria killer was a virus: an "invisible microbe" too small to be seen with the microscopes of the day. He couldn't see these "bacteria eaters" or bacteriophage, but he could grow them, study them, store them and test them. He thought if they could kill bacteria in a test tube, maybe they could kill bacteria in animals and people. He was right, of course. His bacteriophages were viruses. Many of
them look like a cross between a lunar lander and a longnecked spider. Yet, they act more like syringes; injecting their DNA into a bacteria cell in order to take over the cell's genetic machinery and massproduce more copies of themselves. The newly made viruses eventually burst the cell to escape into the environment in search of more hosts. D'Herelle's first test subjects were chickens infected with a salmonella species that caused typhoid, and rabbits infected with a shigella species that caused dysentery. D'Herelle gave his test animals injections or oral doses of his phages and then infected them with bacteria. Most of the recipients of the phage therapy lived. He had similar results treating a highly fatal bloodstream infection in water buffalo. It seemed all he had to do was find a particular phage that would lyse or break open a particular bacterial pathogen, and give it to the infected animal. He needed some human subjects to be sure. After drinking and injecting various phage preparations and asking friends and family members to do the same he decided the phages were safe for human use. In Alexandria, Egypt, he got a chance to test some antiplague preparations on four people with bubonic plague. All four lived. That caught the attention of the medical world, and d'Herelle was invited to India to try phage therapy on cholera patients. It seemed to work there too. (Fifty years later in Pakistan, a study of phages versus tetracycline antibiotics showed the two treatments to be about equal against cholera.) D'Herelle's work with plague in Egypt would later become one of the subplots in Sinclair Lewis' Pulitzer Prizewinning novel "Arrowsmith."
Yet even as phage therapy was making its way into hospital wards, pharmaceutical companies and the popular culture, it was about to be sidelined by two unexpected discoveries. The first was a simple antibacterial chemical called sulfanilamide discovered in the 1930s. The second was the discovery and mass production of penicillin in the 1940s. Unlike the finicky, bacteriaspecific phages, penicillin and sulfanilamide were two "generic" drugs that could kill a wide variety of bacteria. Other such "broadspectrum" antibiotics were discovered and commercialized in the '50s and '60s. It was the end of d'Herelle, Arrowsmith and phagotherapy in the West. But not in the East. In an obscure corner of the Caucasus, in Tbilisi, Georgia, d'Herelle's work lived on. The George Eliava Institute of Bacteriophage, Microbiology and Virology has been producing phages and treating patients for decades. In 2005, the institute created the Phage Therapy Center to commercialize its phage therapies, and recently merged with the American company Phage International. After a long absence, phages may be creeping back into the U.S. In 2006, USA Today carried a story titled, "U.S. needs to open eyes to 'phage therapy.' " Maybe we have. Evergreen State College in Washington is holding its 18th biennial International Phage Biology meeting. Other American researchers are studying ways to reduce bacterial contamination of beef and poultry products with phages. Intralytix Inc. in Baltimore is developing commercial phage products for use in food safety, environmental cleanup, and the treatment of antibioticresistant infections. D'Herelle would be pleased to know his invisible microbes continue to intrigue scientists and save patients.
Dr. Edward McSweegan's column is on hiatus until November.