At the turn of the century, infectious diseases were the leading cause of death in the U.S. Three—tuberculosis, diarrheal diseases and pneumonia—accounted for 30 percent of all deaths and kept life expectancy at about 47 years (as compared with 76 in 1996). But things grew better. Personal hygiene became a higher priority, food and water supplies got cleaned up, sanitation services were vastly improved, and then, just after World War II, what was thought to be a magic bullet came into wide use: penicillin, an antibiotic capable of killing bacteria without harming the human host. It seemed a miracle, but, notes Dr. Mitchell L. Cohen, 50, director of the Division of Bacterial and Mycotic Diseases of the National Center for Infectious Disease of the Centers for Disease Control and Prevention in Atlanta, the battle wasn't over yet.
In time, improper handling of antibiotics and natural evolution conspired to allow bacteria to adapt in order to defend themselves against antibiotics. "Bacteria have a tremendous evolutionary advantage," says Cohen. "They reproduce a lot quicker than we do, and there are a lot more of them." As a result, bacterial diseases thought to be virtually dormant, such as tuberculosis, meningitis and salmonella, have reappeared in recent years in new drug-resistant forms. Viral diseases, such as various flu strains, HIV and the newly discovered and potentially deadly hepatitis C, are resistant to antibiotics and also pose new challenges to researchers. Cohen, who lives in Atlanta with his wife, Jean, 50 (daughter Lindsay, 21, is a biology major at Davidson College, and son David, 16, is a high school student), spoke with correspondent Don Sider about the threat of drug-resistant diseases and the medical community's response.-
When did doctors learn that bacteria could beat antibiotics?
Shortly after penicillin was introduced in the '40s. Penicillin was wonderful; doctors were treating all these infections. But they quickly recognized there were staphylococcal infections that weren't responding. Over time we saw other organisms develop resistant strains. And we were able to switch to alternative antibiotics.
If there were effective alternatives, how did diseases like TB return?
One reason is that in the '80s a number of pharmaceutical companies decided there were enough antibiotics out there. They made a strategic move into creating drugs for chronic diseases like diabetes. So at the same time as societal changes led to more drug-resistant infections, there were fewer alternatives.
What kinds of societal changes?
International travel has become more common. A person from the developing world can be here within 24 to 48 hours and can introduce a drug-resistant or novel agent. Daycare has become more common, and with it the greater spread of disease among children. There's more use of antibiotics—and increased drug resistance.
What about bacteria from food?
When we use antibiotics in agriculture or animals, it can have health consequences throughout the food chain. Farmers began feeding animals antimicrobials to promote their growth or prevent infection. Ultimately bacteria in the animals grew more drug-resistant. This has led to the emergence of a drug-resistant salmonella. It is spread primarily through eating incompletely cooked or mishandled meat, poultry or produce.
Have doctors promoted resistant bacteria by misusing antibiotics?
In 1992 an estimated 110 million antibiotic prescriptions were dispensed in the U.S. Of those, probably 20 percent to even 50 percent were unnecessary because they were given for things like the common cold, which is a virus and is immune to antibiotics. Anytime you use an antibiotic, you help promote resistance. Clearly we can use antibiotics better.
How do bacteria become resistant?
A bacterium reproduces every 20 minutes. So from a single bacterium, in less than a day you can have a billion bacteria. When that occurs, you have resistant mutations. The proven antibiotic kills the regular bacteria but may not affect the mutations. Eventually you may wipe out the original bacteria, but now you may have a billion resistant bacteria within a day.
What can people do to avoid bacterial infection?
It's important that you and your children take all your recommended vaccinations. If you don't get sick, you don't need antibiotics. And wash your hands! A cold is spread by someone's shaking hands. What happens is, I have a cold and I'm rubbing my nose; I shake hands with you. Later you're sitting there, and you're rubbing your nose. That's how a lot of disease transmission occurs, by that kind of contact.
Should we use the antibacterial soaps and lotions on the market?
Probably not. You would be using an antibacterial in a low-priority situation, and you might still be contributing to the creation of resistant bugs. Soap and water do the trick.
Some say there is an epidemic of hepatitis B and C. Is that true?
First of all, those are viruses and can't be treated with antibiotics anyway. But generally, with drug use and the worldwide sexual revolution, there are now millions of people infected with hepatitis B. Fortunately there is a vaccine for B. We don't yet have one for C, which was discovered just a few years ago and which can cause liver failure, cirrhosis, even cancer.
Will we survive the bugs?
I worry when we assume with great hubris that we're able to deal with all of these diseases, that our technology will conquer them, and we don't do some of the things that we need to do, from basic hygiene to having good public infrastructure.
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