TAPPAVATKO ANTIBIOOTIT MEIDÄT?

[Bb]

Lähettäjä: Soijuv Lähetetty: 1.11.2005 19:15

Artikkelissa pohditaan antibioottien käytön vaikutusta terveyteen. Esim. monet reumalääkärit kirjoittavat jopa elinikäisiä antibioottihoitoja niveltulehduksiin vaikka niiden todellisesta hyödystä ei ole kiistatonta näyttöä. Antibioottien käytön ongelmana on se että ne tuhoavat myös hyödylliset bakteerit jotka valmistavat vitamiineja, vaikuttavat hormonitasapainoon ja esim. lihavuuteen. Artikkelin kirjoittajan mukaan antibioottien käyttö saattaa muuttaa bakteeritasapainoa pysyvästi.


http://www.discover.com/issues/nov-05/f ... s-killing/

Are Antibiotics Killing Us?

For every cell in your body, you support 10 bacterial cells that make vitamins, trigger hormones, and may even influence how fat you are. Guess what happens to them when you pop penicillin?.

By Jessica Snyder Sachs
Photography by Joshua Lutz

DISCOVER Vol. 26 No. 10 | October 2005 | Biology & Medicine

A lan Hudson likes to tell a story about a soldier and his high school sweetheart.

The young man returns from an overseas assignment for their wedding with a clean bill of health, having dutifully cleared up an infection of sexually transmitted chlamydia.

"Three weeks later, the wife has a screaming genital infection," Hudson recounts, "and I get a call from the small-town doctor who's trying to save their marriage." The soldier, it seems, has decided his wife must have been seeing other men, which she denies.

Hudson pauses for effect, stretching back in his seat and propping his feet on an open file drawer in a crowded corner of his microbiology laboratory at Wayne State Medical School in Detroit. "The doctor is convinced she's telling the truth," he continues, folding his hands behind a sweep of white, collar-length hair. "So I tell him, 'Send me a specimen from him and a cervical swab from her.' " This is done after the couple has completed a full course of antibiotic treatment and tested free of infection.

"I PCR 'em both," Hudson says, "and he is red hot."

PCR stands for polymerase chain reaction?a technique developed about 20 years ago that allows many copies of a DNA sequence to be made. It is often used at crime scenes, where very little DNA may be available. Hudson's use of the technique allowed him to find traces of chlamydia DNA in the soldier and his wife that traditional tests miss because the amount left after antibiotic treatment is small and asymptomatic. Nonetheless, if a small number of inactive chlamydia cells passed from groom to bride, the infection could have became active in its new host.

Hudson tells the tale to illustrate how microbes that scientists once thought were easily eliminated by antibiotics can still thrive in the body. His findings and those of other researchers raise disturbing questions about the behavior of microbes in the human body and how they should be treated.

For example, Hudson has found that quiescent varieties of chlamydia may play a role in chronic ailments not traditionally thought to be related to this infectious agent. In the early 1990s, he found two types of chlamydia?Chlamydia trachomatis and Chlamydia pneumonia?in the joint tissue of patients with inflammatory arthritis. More famously, in 1996, he began fishing C. pneumonia out of the brain cells of Alzheimer's victims. Since then, other researchers have made headlines after reporting the genetic fingerprints of C. pneumonia, as well as several kinds of common mouth bacteria, in the arterial plaque of heart attack patients. Hidden infections are now thought to be the basis of still other stubbornly elusive ills like chronic fatigue syndrome, Gulf War syndrome, multiple sclerosis, lupus, Parkinson's disease, and types of cancer.

To counteract these killers, some physicians have turned to lengthy or lifelong courses of antibiotics. At the same time, other researchers are counterintuitively finding that bacteria we think are bad for us also ward off other diseases and keep us healthy. Using antibiotics to tamper with this complicated and little-understood population could irrevocably alter the microbial ecology in an individual and accelerate the spread of drug-resistant genes to the public at large.

The two-faced puzzle regarding the role of bacteria is as old as the study of microbiology itself. Even as Louis Pasteur became the first to show that bacteria can cause disease, he assumed that bacteria normally found in the body are essential to life. Yet his protégé, Élie Metchnikoff, openly scoffed at the idea. Metchnikoff blamed indigenous bacteria for senility, atherosclerosis, and an altogether shortened life span?going even so far as to predict the day when surgeons would routinely remove the human colon simply to rid us of the "chronic poisoning" from its abundant flora.

Today we know that trillions of bacteria carpet not only our intestines but also our skin and much of our respiratory and urinary tracts. The vast majority of them seem to be innocuous, if not beneficial. And bacteria are everywhere, in abundance?they outnumber other cells in the human body by 10 to one. David Relman and his team at Stanford University and the VA Medical Center in Palo Alto, California, recently found the genetic fingerprints of several hundred new bacterial species in the mouths, stomachs, and intestines of healthy volunteers.

"What I hope," Relman says, "is that by starting with specimens from healthy people, the assumption would be that these microbes have probably been with us for some time relative to our stay on this planet and may, in fact, be important to our health."

Meanwhile, the behavior of even well-known bacterial inhabitants is challenging the old, straightforward view of infectious disease. In the 19th century, Robert Koch laid the foundation for medical microbiology, postulating: Any microorganism that causes a disease should be found in every case of the disease and always cause the disease when introduced into a new host. That view prevailed until the middle of this past century. Now we are more confused than ever. Take Helicobacter pylori. In the 1980s infection by the bacterium, not stress, was found to be the cause of most ulcers. Overnight, antibiotics became the standard treatment. Yet in the undeveloped world ulcers are rare, and H. pylori is pervasive.

"This stuff drives the old-time microbiologists mad," says Hudson, "because Koch's postulates simply don't apply." With new technologies like PCR, researchers are turning up stealth infections everywhere, yet they cause problems only in some people sometimes, often many years after the infection.

These mysteries have nonetheless not stopped a free flow of prescriptions. Many rheumatologists, for example, now prescribe long-term?even lifelong?courses of antibiotics for inflammatory arthritis, even though it isn't known if the antibiotics actually clear away bacteria or reduce inflammatory arthritis in some other unknown manner.

Even more far-reaching is the use of antibiotics to treat heart disease, a trend that began in the early 1990s after studies associated C. pneumonia with the accumulation of plaque in arteries. In April two large-scale studies reported that use of antibiotics does not reduce the incidence of heart attacks or eliminate C. pneumonia. But researchers left antibiotic-dosing cardiologists a strange option by admitting they do not know if stronger, longer courses of antibiotics or combined therapies would succeed.

Meanwhile, many researchers are alarmed. Infectious-diseases specialist Curtis Donskey, of Case Western Reserve University in Cleveland, says: "Unfortunately, far too many physicians are still thinking of antibiotics as benign. We're just now beginning to understand how our normal microflora does such a good job of preventing our colonization by disease-causing microbes. And from an ecological point of view, we're just starting to understand the medical consequences of disturbing that with antibiotics."

Donskey has seen the problem firsthand at the Cleveland VA Medical Center, where he heads infection control. "Hospital patients get the broadest spectrum, most powerful antibiotics," he says, but they are also "in an environment where they get exposed to some of the nastiest, most drug-resistant pathogens." Powerful antibiotics can be dangerous in such a setting because they kill off harmless bacteria that create competition for drug-resistant colonizers, which can then proliferate. The result: Hospital-acquired infections have become a leading cause of death in critical-care units.

"We also see serious problems in the outside community," Donskey says, because of inappropriate antibiotic use.