Information Related to "Common Bacteria Make a Deadly Comeback"
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by Jerold Aust
Food contamination isn't just a simple stomach ache anymore. Sixteen-month-old Anna Grace Gimmestad of Evans, Colorado, loved fruit juices. When she went grocery shopping with her mother, she would excitedly point to the colorful, fruity juices on the shelf.
In late 1996 little Anna fell ill after drinking some tainted apple juice. Within two weeks her kidneys failed, her heart faltered, and she died. The juice she drank was contaminated with one of America's increasingly troublesome pathogens: a strain of bacteria known as E. coli 0157.H7.
This deadly strain has been found in fresh-fruit juices and vegetables-ironically the very foods Americans desire most in their pursuit of good health. (Of course, this incident and some other relatively isolated instances by no means constitute sufficient grounds to cease buying these food products.)
E. coli infects as many as 20,000 Americans every year, mostly through meat, and about 500 die. E. coli 0157.H7 was first identified in food in 1980, and sporadic outbreaks have become increasingly more frequent.
Although the nation's food supply remains one of the safest in the world, it apparently is not good enough always to catch such virulent strains. Inattention to health safeguards can make the difference between life and death. Apparently the batch of apples that wound up in the juice little Anna Gimmestad drank had fallen to the ground and come in contact with deer feces. Safeguards that should have prevented this tragedy failed.
Is this an isolated incident, or are there other dangerous bugs that can intrude into our lives, breaking down the perceived wall of protection we assume that science and medicine have built?
Over the last year a series of troubling reports has described how microorganisms are fighting back, mutating into strains resistant to the most powerful antibiotics in the medical arsenal. Among them are such killers as tuberculosis, bubonic plague and staphylococcus (staph) bacteria.
The battle against the bugs
Just 15 years ago most staph infections responded to a wide range of antibiotics.
But
in the early 1980s a specific strain surfaced that medical practitioners found resistant
to methicillin, then the drug of choice to combat the ubiquitous staph bacteria.
However, some strains of staph found ways to mutate around its killing properties, and today methicillin is useless against half of all staph infections. The omnipresent bug has developed resistance to other drugs as well. Because bacteria and viruses can mutate rapidly, researchers must constantly develop new antibiotics to stay one step ahead in effective treatments.
In recent years, however, such advancements have begun to stall. Vancomycin, the last antibiotic with a clear knockout punch against bacteria, is showing signs of faltering as new strains emerge. The notion that science has given us permanent victory over infectious diseases may prove to be illusory.
"We don't have any new drugs, really new ones, of the vancomycin type coming through in the next few years, and it concerns me that we're going to lose the one we can count on," said Stuart Levy, director of the Center for Adaptation Genetics and Drug Resistance at Tufts University Medical School in Boston.
An alarming development
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Malaria Poses a New Threat Malaria, a disease that comes to
humans through tropical mosquitoes, |
A notable case illustrating the challenge medicine faces involved a patient from Michigan. His case might well prove a harbinger of more significant health problems ahead, according to public-health officials who noted that similar instances of drug resistance in previously susceptible bacteria have become more and more common around the world.
The Michigan patient became infected with a strain of Staphylococcus aureus, a common bacterium that manifests itself in ailments ranging from pimples and boils to fatal septic infections in surgical patients. Because of kidney failure, this patient relied on a home dialysis system to cleanse his blood in place of his failed kidneys. The procedure required a tube to remain in the patient's abdomen. Since this process makes patients prone to frequent infections, treatments with vancomycin were used to control and eradicate occasional staph infections.
However, in this case the miracle drug proved less effective than usual. Tests done and confirmed by the Centers for Disease Control and Prevention (CDC) revealed that this newly discovered strain of bacteria had developed the ability to survive moderate levels of vancomycin given intravenously. Although a previous single case was recorded in Japan, this was the first time vancomycin-resistant staph had been discovered in the United States.
The problem of overprescribing
William Jarvis, epidemiologist and acting director of the CDC's hospital infection
program, thinks that this drug-resistant strain of staph has developed largely because
of doctors overprescribing vancomycin when less-potent drugs would have sufficed.
The more a strain of bacteria comes
into contact with a given antibiotic, he explained, the more opportunities it has
to develop a way to resist that drug's effects.
"It's become common practice in some dialysis centers that if a patient develops a fever or pain at the catheter site or some other nonspecific symptom, they'll give them a bolus of vancomycin," he said. "That practice has clearly got to stop. We have recommended that, . . . if it is susceptible to other antibiotics, then we must use those instead."
Dr. Jarvis is concerned not just with the overprescribing of vancomycin and other antibiotics, but with the lack of funding necessary for state and local laboratories to track the emergence of resistant bacteria.
Anthony S. Fauci, chief of the National Institute of Allergy and Infectious Diseases, defends the use of vancomycin in cases in which seriously ill patients need to be treated immediately. In such serious cases "you don't want to take a chance and you have to go with your big guns," he said. Dr. Fauci indicated that, if subsequent testing shows a lesser drug will work, then in many cases the patient can be safely switched to a less-potent drug. This reserves vancomycin for emergencies.
For the first time in the history of the United States, scientists have found a strain of staphylococcus bacteria that can resist treatment with vancomycin. Up until recently this superpowerful antibiotic proved 100 percent effective against this threatening microbe.
Many doctors are now placing their hope in Synercid, a new antibiotic developed in France. But even this drug is no silver bullet against infections; in some studies it has not proved as effective as existing antibiotics.
The regular mutation of bacteria and viruses is what makes development of effective
treatments and vaccines against HIV, the virus that causes AIDS, so maddeningly difficult.
The virus has so far
been able to mutate at a rate faster than researchers can develop weapons with which
to fight it. By the time treatments are devised, tested and put into use, new strains
have emerged that are resistant to those treatments.
Stemming antibiotic resistance
There are some encouraging signs in the battle against drug-resistant microbes.
If doctors and patients change their behavior, they may be able to slow the spread
of drug-resistant bugs. Finland
has noted a favorable change in human behavior and a corresponding reduction in antibiotic-resistant
bacteria. Similarly, New York has noted a dramatic drop in the frequency of drug-resistant
tuberculosis after adopting a newly revitalized tuberculosis-control program.
But we might be surprised how much people have come to depend on antibiotics to cure their illnesses. In the United States one fourth of Streptococcus pneumoniae bacteria (which cause ear infections, pneumonia and meningitis) are resistant to penicillin. Longer hospital stays and higher mortality rates are associated with resistant organisms, especially in hospitals.
Experts warn that, if vancomycin resistance develops in the common staph bacteria, it will precipitate a monstrous medical problem. "I think it's important to be aware of this before we do reach the end of the rope," said Morton N. Schwartz, professor of medicine at Harvard Medical School.
Doctors and patients aren't the only ones who must consider the overuse of antibiotics. Fully 40 percent of the antibiotics produced in the United States in the early 1980s was given to livestock. Fruit growers also use such potent drugs. Of the 15,700 tons of antibiotics produced in that period, 300,000 pounds were sprayed on pears, apples and other fruit, ostensibly to prevent a blight that causes scaling on fruit skin.
"We are just covering the world with this thin layer of antibiotics, which is selecting out (bacterial) resistance," said David L. Heymann, director of the World Health Organization (WHO) division on emerging diseases.
Drugs change the environment of bacteria, killing sensitive strains and providing a survival advantage for germs whose genetic traits permit them to withstand and overcome potent antibiotics. Eventually each individual and society are at greater risk. Thus we can understand why some observers feel that antibiotics should be used more sparingly.
The Centers for Disease Control and Prevention estimate that more than 50 million of the 150 million antibiotic prescriptions written annually for patients outside of hospitals are not needed. Eliminating unnecessary prescriptions could greatly reduce the ability of bacteria and viruses to develop resistance to drugs.
Experts urge this change of human behavior in an effort to stem the rising tide of antibiotic resistance. Otherwise we might be creating a specter that can come to haunt us, the likes of which mankind hasn't experienced since the plagues that wiped out much of the world in the Dark Ages. GN
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The World's Most Deadly Disease It is an epidemic of unprecedented proportions. It kills more adults worldwide than all other infectious diseases combined, and nearly half of the world's refugees may be infected with it. It is the leading killer of people with human immunodeficiency virus (HIV) and orphans more children than any other infectious disease. It's not AIDS, nor hepatitis, nor malaria, but an ancient disease that was nearly eradicated a generation ago: tuberculosis. According to the World Health Organization (WHO), almost two billion people-one third of the world's population-are infected with tuberculosis (TB) bacteria. Each year eight million new cases of TB appear, along with three million TB-related deaths. At current rates the WHO estimates that as many as 500 million people will become ill from TB during the next 50 years. TB is not a disease limited to the developing world. In the United States alone it is estimated that 10 million to 15 million people are infected with the TB bacterium, and 22,000 new cases of TB occur each year. Yet, only 15 to 20 years ago, health authorities were about ready to declare that TB, like smallpox and polio, had been wiped off the face of the earth. In the United States during the early 1900s, TB was the No. 1 killer. Then, in the 1940s, the introduction of antibiotic drugs that could kill TB bacteria meant that the disease could be cured. For three decades, from the 1950s to the mid-1980s, TB cases steadily declined. But in the 1980s the battle against tuberculosis took a turn for the worse. The disease reemerged and spread in industrialized countries and underdeveloped nations. Between 1985 and 1992 the number of TB cases increased by nearly 20 percent in the United States. Worldwide, the modern TB epidemic led the WHO in 1993 to declare its first "global emergency." At the time, TB was killing more adults each year than AIDS, malaria and tropical diseases combined. TB is caused by a bacillus, Mycobacterium tuberculosis. A person can become infected with the tuberculosis bacterium when microscopic airborne particles of infected sputum are inhaled. The bacteria get into the air when someone who has tuberculosis infection of the lung coughs, sneezes, shouts or even laughs. People who are nearby can breathe the bacteria into their lungs. For most people who inhale TB bacteria and become infected, the body is able to fight the bacteria to stop them from spreading. The bacteria become inactive, but they remain alive in the body and can become active later. This is called TB infection. People with TB infection do not feel ill, have no symptoms and do not spread TB to others. The infection can remain dormant in a person's body for decades, then flare into active disease when the body's immune system is weakened for any reason. About 10 percent of infected people develop TB at some point. TB can attack any part of the body but usually targets the lungs. When a person breathes in TB bacteria, they can settle in the lungs and begin to grow, then move through the blood to other parts of the body, such as the kidney, spine and brain. Although TB in the lungs or throat can be contagious, TB in other parts of the body is usually not contagious. Usual symptoms of the disease are a general fatigue or weakness, extreme weight loss, fever and night sweats. If the infection in the lung worsens, then further symptoms can develop, including persistent coughing, chest pain, coughing up of blood and shortness of breath. Because TB is spread through airborne bacteria, anyone can become infected. Groups with the highest risk are the poor and homeless, as well as those with undeveloped or suppressed immune systems: young children, the elderly, HIV-positive people and patients with certain types of cancer. New and deadly strains Health-care officials are increasingly concerned about emerging new forms of drug-resistant TB. According to the WHO, outbreaks of drug-resistant tuberculosis are showing up all over the world and threaten to touch off a worldwide epidemic of virtually incurable tuberculosis. Drug-resistant strains have appeared in New York City prisons, a hospital in Milan, Italy, and many places in between. "Everyone who breathes air, from Wall Street to the Great Wall of China, needs to worry about this risk," says Dr. Arata Kochi, director of the WHO Global TB program. An October 1997 survey by the WHO, the U.S. Centers for Disease Control and Prevention and the International Union Against Tuberculosis and Lung Disease estimates that 50 million people are infected with a strain of TB that is drug-resistant. Many of those are said to carry multi-drug-resistant tuberculosis-incurable by two or more of the standard drugs. In underdeveloped countries, where the vast majority of multi-drug-resistant TB cases have occurred, it is usually fatal. "The world is becoming smaller and the TB bugs are becoming stronger," Dr. Kochi says. "While international travel has increased dramatically, the world has been slow to realize the implications for public health. Only recently have wealthy governments begun to recognize that the poor TB treatment practices of other countries are a threat to their own citizens." The WHO study identifies hot zones of untreatable tuberculosis that threaten a worldwide crisis. These zones are home to nearly 75 percent of the world's TB cases and include Russia, Bangladesh, Brazil, China, Ethiopia, India, Indonesia, Mexico, Pakistan, the Philippines, South Africa, Thailand and Zaire. Many of the hot zones are regional centers for travel, immigration and international economic activity. WHO officials admit that little can be done to prevent people infected with drug-resistant TB from traveling and spreading the bacilli to other countries. According to the WHO, one third of the world's nations have a strain of TB resistant to multiple drugs. Untreatable cases account for 2 to 14 percent of the world's total. That number is low, but the WHO said lethal tuberculosis could spread rapidly because only one in 10 patients gets medical care that could overcome drug resistance. Drug-resistant strains of TB develop when patients do not complete the course of treatment, fail to take their medicine or don't use medication properly. Tuberculosis often can be cured with a combination of four drugs taken for six to nine months. But some patients may begin to feel better after just two to four weeks of treatment, so they stop their medication. But not enough of the medication has been taken to kill all the TB bacteria in the patient. The remaining bacteria survive and mutate, becoming a tenacious, more deadly form of the disease. TB can be diagnosed in several ways. Chest X rays can reveal evidence of active tuberculosis pneumonia, or they may show scarring, suggesting contained inactive TB. Examination of sputum under the microscope can show the presence of tuberculosis bacteria. A sample of the sputum can also be grown in special incubators, and tuberculosis bacteria can subsequently be identified. Several types of skin tests are used to screen for TB. Tuberculin skin tests include the Mantoux test, the Tine test and the PPD. In each of these tests, a small amount of dead tuberculosis bacteria is injected under the skin. If a person is not infected with TB, no reaction at the site of the injection will become apparent. However, if a person has become infected with tuberculosis, an area around the site of the test injection will redden and swell. This reaction occurs 48 to 72 hours after the injection. Treatments can work Health-care authorities believe one of the best ways to treat TB is something known as "DOTS" (directly observed treatment, short course). Health workers make sure that TB patients take their medicine by watching them swallow every dose they take. Patients take all their medicine, their TB is cured, and the development of drug-resistant tuberculosis is prevented. According to the WHO, only 10 percent of the world's TB patients are being treated using DOTS. If DOTS were used, WHO officials maintain that nearly three fourths of TB cases could be cured. "DOTS cures sick patients and prevents drug resistance," says Dr. Kochi. "Alarmingly, only about one in 10 TB patients today has access to DOTS. We have to quickly put more DOTS programs in place to stop multi-drug-resistant TB from increasing." "The TB epidemic must be fought globally to protect people locally," Dr. Kochi warns. "It is in the interest of the wealthy countries to help less-developed countries fight tuberculosis, before their own countries become the battleground." -Becky Sweat |
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Keywords: food supply micro-organisms infections disease
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