A new scientific discovery soon may provide an alternative to antibiotics for the treatment of diseases caused by bacterial infections.
Microbiologists at the University of California, Los Angeles recently reported that bacteriophages -- viruses that infect bacteria -- can be genetically engineered to seek out and destroy specific types of disease-causing bacteria. The results of their research appeared in the September 2004 issue of the journal Nature.
At a time when antibiotic-resistant bacteria are becoming increasingly common and tougher to treat, the discovery is welcome news. According to the Centers for Disease Control and Prevention, virtually all significant disease-causing bacteria in the world are becoming resistant to the antibiotic treatment of choice.
Antibiotic resistance isn't a new phenomenon. Just four years after drug companies began mass-producing penicillin in 1943, scientists documented the emergence of penicillin-resistant bacteria.
With each passing decade, more bacteria are becoming resistant not just to a single antibiotic, but to several. In some cases, these new bacterial super bugs totally defy treatment.
Drug-resistant strains of bacteria are especially problematic for hospitalized patients. Each year in the United States, approximately 90,000 people die from infections acquired during hospital stays. The vast majority of these infections are caused by antibiotic-resistant organisms.
At the very least, diseases caused by antibiotic-resistant bacteria are likely to last longer and spread faster from person to person. They typically necessitate additional visits to doctors' offices and more expensive treatments.
Bacterial resistance can develop any time antibiotics are administered, but it is most likely to occur when the medications are used improperly or inappropriately. The widespread practice of using of antibiotics to treat viral infections, including the common cold and influenza, is largely responsible for creating antibiotic resistance in many bacteria.
Once bacteria are exposed to a particular antibiotic, they begin to "outsmart" it by undergoing mutations that change their structure or metabolism, making them impervious to the drug. Mutations are quickly transferred to future generations, as well as to other types of bacteria, making them harder to control.
Jeffery F. Miller, professor of microbiology at UCLA and lead investigator of the recent study, says that bacteria aren't able to outsmart bacteriophages quite so easily. "As a bacterium mutates in an effort to become resistant," Miller explained, "the bacteriophage mutates along with it, so that it can still kill the bacterium."
A bacteriophage works by latching onto a disease-causing bacterium and injecting its genetic material into the organism. Under the control of the injected genes, the bacterium begins to mass produce bacteriophage offspring.
Eventually, the offspring become so numerous that they burst out of the bacterium, killing it in the process. Newly released bacteriophages repeat the cycle, until the disease-producing bacteria are completely eliminated.
Bacteriophages, which are about 1/4 0th the size of most bacteria, are the most abundant life form on earth, according to Miller. "It's a bit ironic to think that viruses can be used to cure bacterial diseases," he said. "They're nature's antimicrobial agents."
The use of bacteriophages to treat bacterial infections isn't an entirely new concept. Bacteriophage therapy has been practiced for nearly a hundred years in some parts of the world, primarily Europe. Although it was briefly tried in the U.S. more than half a century ago, the practice fell from favor when antibiotic drugs became readily available.
Without the benefit of modern technology, early bacteriophage therapy wasn't always successful. In those days, doctors had to use a trial-and-error approach to determine which bacteriophages were capable of killing disease-causing bacteria.
"As we return to the use of bacteriophage therapy," Miller says, "we have a much more sophisticated approach. Now, we can determine the exact genetic sequence of a bacteriophage in a matter of hours, and we can genetically engineer it to target a specific type of bacteria."
Miller foresees dozens of potential therapeutic uses for bacteriophages.
For starters, he predicts that scientists will be able to tailor the organisms to destroy drug-resistant bacteria.
It is likely that bacteriophages will be designed to kill bacteria responsible for causing all types of conditions, ranging from acne to pneumonia.