by Alice Tallmadge
to find an antibiotic that can effectively fight certain
infections is becoming more frequent as antibiotic-resistant bacteria
proliferate around the globe. The war between antibiotics and bacteria has
been waging since the 1940s, when researchers first developed the
breakthrough drug, penicillin. Since then, antibiotics have been
consistently victorious against a whole range of disease-producing bacteria,
including those causing tuberculosis, pneumonia, gonorrhea and staph.
Western medicine practitioners and patients were triumphant and grateful.
Recent developments, though, are revisioning that "victory." From all around the globe -- Japan, the U.S., Europe, South America -- reports of antibiotic resistant strains of bacteria are surfacing: urinary, respiratory and ear infections that don't respond to usual courses of antibiotics; resistant strains of pneumonia and tuberculosis bacteria. In addition, some bacteria strains transmitted only in hospital settings are also showing resistance.
"Is this a problem? Yes. And use all capital letters to spell yes," says Dr. Paul Lewis, an assistant professor in pediatric infectious diseases at Oregon Health Sciences University in Portland.
In general, bacteria are specifically adapted "to make people sick," Lewis says. And antibiotics were specifically engineered to kill those bacteria. However, he says, 40 years of widespread use - and often overuse -- of antibiotics has created its own monster: bacteria that have figured out how to avoid being affected by Western medicine's antibiotic "wonder drugs" while still making people ill.
These days, many types of infections, says Lewis, "are more difficult to treat because they're more resistant to antibiotics." And even people who avoid taking antibiotics may not be able to keep these resistant bugs at bay, he says, because it's the bacteria, not individuals, who are becoming more resistant. And that's why, says Lewis, the overuse of antibiotics hurts everyone. "When our fellow citizens are treated [with antibiotics] unnecessarily, it exposes us all to more difficult- to- treat organisms," he says.
concern about antibiotic resistant bacteria gave rise in 1997 to the
Sentry Project, funded by the Bristol-Myers Squibb Co., which is tracking
resistance in various sites around the world. Early reports have already
found high rates of penicillin-resistant S. pneumoniae in the U.S., Canada
and Europe. In South America, researchers have found high highly resistant
strains of bacteria linked to urinary and respiratory infections.
In a January 1997 story on the PBS newshow, "The NewsHour with Jim Lehrer," reporter Tom Bearden noted that "every one of the 160 antibiotics on the market today have been compromised by at least one resistant strain of bacteria, and the list is growing every day."
Those whose job it is to monitor resistant bacteria say the problem is beginning to surface in Oregon, as well. Lewis estimates that, in Portland, 10 percent of the cases involving Staphylococcus aureus, the bacteria that causes staph infections, is resistant to "first line" antibiotic treatment.
Donna Gulbranson, infection control practitioner at Portland's Sacred Heart Medical Center, says the hospital itself has not seen "a whole lot" of resistant bacteria. "Occasionally we have patients admitted who come in with it," she says. "They usually come from nursing homes or are a person who's taken a lot of antibiotics in the past and has become resistant."
The resistant bug the hospital sees most of, she says, is a strain of S. aureus that is resistant to the antibiotic, methicillin. Researchers are also tracking this bacteria closely. It has been found to be responsible for 60 percent of infections in European intensive care units and for about 30 percent of staph infections in U.S. and South American hospitals. Currently, physicians can use another antibiotic, vancomycin, to kill that particular strain of staph. But, Gulbranson says, the fear of researchers is that, eventually, methicillin-resistant bacteria will "mutate" and become resistant to vancomycin.
Last year, that's exactly what happened. According to the Journal of the American Medical Association, Japanese researchers "fired a shot heard around the microbiological world with their announcement of the emergence of a vancomycin-resistant strain of Stapholococcus aureus." Within months, the article says, two hospital patients in Michigan and New Jersey had staph infections that were resistant to vancomycin, "the drug considered the last uniformly effective antibiotic against this bacterium for serious infections."
Lewis says the public's broad acceptance of antibiotics and misperceptions about what antibiotics can and cannot do have lead to the current dilemma. Because antibiotics work so well and so fast, patients want them, even when they're not appropriate, he says. For instance, antibiotics do not kill viruses, which can cause a whole host of illnesses, including the common cold.
"An example of inappropriate use is giving antibiotics to someone with a runny nose," says Lewis. "Antibiotics are not for treating a runny nose, whether the discharge is clear, white, yellow or green. But too often doctors succumb to pressures from patients or parents to prescribe the drug, he says.
factor that has been implicated in the rise of antibiotic resistant
bacteria is the widespread practice of adding antibiotics to animal feed.
Ranchers have known for years that low levels of antibiotics makes young
chickens and pigs fatten quickly. (Cattle, because of their complicated
digestive systems, are not fed antibiotics). And they insist that the
practice does not hurt humans. Lewis, however, insists that the inevitable
result of feeding animals antibiotics is that the general environment
contains "more and more resistant bacteria."
Peter Cheeke, professor of animal science at Oregon State University, disagrees. "No studies have shown a relationship between feeding antibiotics as growth promoters in animals and effects on human health," says Cheeke, who addressed the issue in his recently-published book, Contemporary Issues in Animal Agriculture.
However, a March 1998, article in the Times of London says that a recent study by researchers in Denmark produced for the first time a "clear link" between the use of antibiotics in animal feed and the emergence of "superbugs" in hospitals. The study, the article said, "suggests that a common type of bacterium found in the intestine developed resistance to vancomycin, a widely used antibiotic, when a similar drug was used in animal feed."
Cheeke does admit that the perception that there is a connection between feeding animals antibiotics and resistant bacteria might have a "potent" effect on consumer demand. Research is currently underway, he says, to come up with an alternative. Two possible options include flooding young chicks with beneficial bacteria (such as lactobacillus acidophilus) to inhibit the growth of pathogens. Another is treating the chicks with cultures of normal "gut" bacteria to out-compete pathogens such as salmonella and E. coli. Neither option, Cheeke says, has yet been shown to be as effective as antibiotics for promoting growth.
The control mechanism being called for by the medical establishment is disarmingly simple, but crucial -- reduce unnecessary use of antibiotics. Lewis says it remains unclear whether a local reduction in antibiotic use may have a positive effect. But the country of Finland, he says, limited its overall antibiotic use, and the results "showed a favorable change in the resistant pattern of bacteria." But for at least one Portland intensive care unit nurse, who asked not to be named, the situation is a like watching a dread inevitability creep closer and closer to home. Resistant bugs, the nurse says, are starting to show up in this area. And, so far, "the nasty ones are susceptible to vancomycin." But there will come a day when they are not. And although the scenario remains in the future, the nurse says, "there's sense of dread about when that does happen."
Albion Monitor August 3, 1998 (http://www.monitor.net/monitor)
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