A: Antibiotics are designed to kill bacteria, but a tiny fraction of the bacteria may have the ability to survive. When the antibiotic kills off their competitors, only the resistant bacteria multiply. And they can pass their resistance on to their progeny and to other types of bacteria.

     Using antibiotics inappropriately encourages resistance without providing any health benefit. For example, if you take antibiotics for a cold or some other infection that’s caused by a virus and not bacteria, two things happen: the antibiotics won’t help your cold, and you can create resistance in the bacteria that naturally reside in your body. But there are other ways to get resistant infections, and rates of resistance are picking up.

Q: Where else can antibiotic-resistant bacteria come from?

A: Food can spread resistant bacteria, as a recent study from the University of California at Berkeley showed. Researchers studied female college students living in California, Michigan, and Minnesota who were diagnosed with urinary tract infections, or UTIs. Twenty percent had E. coli infections that were resistant to Bactrim, or trimethoprim-sulfamethoxazole, the antibiotic usually used to treat UTIs.

     And some of the Bactrim-resistant E. coli also were resistant to other antibiotics. What’s more, the Bactrim-resistant E. coli in all three states were very similar, which means that they all had to have come from a common food source. This study was a real eye-opener, because it’s the first time anyone appreciated that resistant UTIs could be epidemic in the population.

Q: Bactrim used to work in most people?

A: Yes. Bactrim has been a favorite because it’s very effective—treatment only takes three days. It’s also inexpensive, and it knocks out fewer beneficial bacteria than Cipro.

Q: Will doctors stop using Bactrim to treat urinary tract infections?

A: Many will. With one in five UTIs resistant to Bactrim, it will be harder for doctors to use it as a frontline drug. If you fail to get rid of the infection the first go-round, the patient has a greater chance of getting kidney infection, flank pain, high fever, or other complications.

     The back-up drugs are the fluoroquinolones like Ciprofloxacin, which we’ve all heard of because it’s used to treat anthrax. When a patient comes in with a UTI, I would now use Cipro or another fluoroquinolone to treat it.

Q: Even though the Bactrim study only looked at three states?

A: Yes. The researchers found that a large fraction of the resistant infections were caused by the same strain of E. coli bacteria, which had reached across three states. They only looked at three, but they found it in all of them, which suggests that if they had looked at more states, they would have found it there as well.

Q: What’s wrong with using Cipro?

A: It’s more expensive, it has more side effects, and it kills more bacteria that might be beneficial. Cipro is used for serious, tougher-to-treat infections. It was better to use Bactrim for less serious infections like UTIs, because Bactrim isn’t often used for tougher infections. Now we’ve lost that option.

Q: What if a UTI is also resistant to Cipro?

A: Most doctors could figure out how to treat a patient with a urinary tract infection that was resistant to both Bactrim and Cipro. But you’ve knocked off the two major treatments, and the infection is probably not sensitive to a few other drugs as well. And at some point, we may simply run out of antibiotics that work.

Q: Do people who take Cipro for no reason promote Cipro-resistant bacteria?

A: Yes. People who aren’t at risk but manage to get some antibiotic from their physician or over the Internet are getting no benefit from the drug. And they’re putting their health at risk because they’re promoting the growth of resistant bacteria in their bodies.

     If, for example, they happen to get a urinary tract infection from a strain of Cipro-resistant bacteria, they’ll be much harder to treat, because doctors could no longer give them Cipro. They could end up in a hospital getting antibiotics that can only be given intravenously. And all because they gave themselves an unnecessary treatment.

     On the other hand, anyone who is told by health authorities to take an antibiotic like Cipro or doxycycline should take it. Even if that encourages some resistant bacteria to grow, it could save their lives.

Q: How could food spread resistant bacteria to three states at the same time?

A: Food is manufactured in one place then shipped and sold all over the country or all over the world. It’s hard to think of what else could introduce a new strain and hit three geographically separate states so quickly, except for food.

Q: UTIs don’t spread from person to person?

A: No. E. coli lives in everybody’s gut. It causes an infection when it goes from your gut to your pelvic area and into your bladder. Plus, it would be unlikely for a resistant strain of E. coli to be passed from person to person in three different states. When you look at what could do that, it’s a very short list. Food is at the very top.

Q: How did the resistant E. coli get on the food in the first place?

A: We’re not sure. But many of our antibiotics, including Bactrim-like drugs, are used to treat or prevent disease in cattle, chickens, and other farm animals or to make them grow faster. That practice increases the odds that the animals will harbor bacteria that are resistant to Bactrim. And that means that these drugs may not be effective for us when we need them.

Q: The same antibiotics used for people are also used to treat livestock?

A: Yes. They’re often given to healthy animals. As farms have gotten bigger, the animals are more crowded, and that raises their risk of disease. By giving them antibiotics before they get sick, farmers can push them through the livestock system more efficiently and more profitably. But that also promotes the growth of resistant bacteria that can end up in humans.

Q: Could farmers raise the animals without antibiotics?

A: Yes, but they would have to keep the farms cleaner and decrease crowding. The dirtier the farm, the more likely farmers are to benefit from antibiotics. Removing antibiotics would raise the price of meat and poultry slightly—by $5 to $10 per person per year, according to a recent estimate. But it would be worth every penny to keep our food from transmitting antibiotic-resistant bacteria that put us at risk for drug-resistant infections. We’ve got to stop giving animals the same antibiotics that people need, or we’ll end up with infections we can’t treat.

Q: Which foods are most likely to carry antibiotic-resistant bacteria?

A: Meat and poultry are the most likely candidates, because the animals are being fed the antibiotics and their meat can become contaminated with bacteria when they’re slaughtered.

     In theory, resistant bacteria could also end up in any food, even fruits and vegetables, if the bacteria get into the environment through the animals’ waste, and the waste ends up in fertilizer.

Q: How likely is meat to harbor drug-resistant bacteria?

A: In October, a study by the Food and Drug Administration found that 20 percent of supermarket samples of ground beef, pork, chicken, and turkey were contaminated with Salmonella. Even more worrisome, 84 percent of the Salmonella were resistant to at least one antibiotic and half were resistant to at least three antibiotics. Sixteen percent were resistant to the drug of choice for treating Salmonella infections in children.

     So we not only have to worry about getting Salmonella poisoning from food if we don’t prepare it properly. We also have to worry that it would be harder to treat food poisoning because the Salmonella is antibiotic-resistant.

Q: Are bacteria other than Salmonella and E. coli resistant to antibiotics because the drugs are used in livestock and poultry?

A: Yes. One out of six Campylobacter infections are now resistant to fluoroquinolone antibiotics like Cipro, which are used both in humans and poultry. And that’s a serious problem, because Campylobacter causes more food poisoning than any other bacteria.

     And the Centers for Disease Control and Prevention recently found that more than half of the chickens purchased in four states were contaminated with Enterococcus bacteria that were resistant to the antibiotic virginiamycin.

Q: What’s the link with humans?

A: In the past, virginiamycin was used only in animals. But a few years ago, pharmaceutical companies developed a virginiamycin-like drug called Synercid to treat enterococcal infections in humans that were resistant to other antibiotics.

     Enterococcus is a normal resident of the human gut and isn’t usually a problem in healthy people. However, it can cause infections in patients with cancer and some other medical conditions. So far, researchers have only found a few people with Synercid-resistant Enterococcus in their gastrointestinal tracts. But as more patients are given Synercid, the number of cases of resistance could rise dramatically.

     The bottom line is that virginiamycin and other antibiotics that are used in agriculture create a population of antibiotic-resistant germs that put us all at risk. That’s why we need to phase out the unnecessary use of antibiotics in animals.

Q: Aren’t pharmaceutical companies developing new antibiotics all the time?

A: Few new drugs are coming down the pike. In the last 35 years, we’ve only had one completely new class of antibiotics and only a couple of recent FDA approvals. We may reach a point where we have no treatments for some infections, and that’s very scary.

Q: What can the government do?

A: The Food and Drug Administration should phase out the use of medically important antibiotics to promote growth and prevent disease in livestock. In the 1970s, the FDA asked animal producers to show that their use of penicillin and tetracycline caused no harm to humans. When they couldn’t, the agency banned the use of the drugs in animals. But under pressure from the drug and animal industries, Congress stepped in and ordered the FDA not to implement its ban.

     In 2000, the FDA proposed a ban on the use of fluroquinolones by poultry producers, but the agency needs to go further. Now that we have more evidence, it should again try to phase out the use of medically important antibiotics in animals unless the pharmaceutical and agricultural industries can prove that they don’t put people at risk of getting drug-resistant infections. And if the FDA can’t act, Congress should. The European Union has phased out that use because it jeopardizes the health of people.

Q: What can people do to help keep antibiotics from becoming useless?

A: The most important thing is to not demand that their doctors give them antibiotics to treat bronchitis, the flu, or other viral infections, which the drugs can’t cure.

     Then they should ask their Congressperson, their Senators, and the FDA to act on CSPI’s 1999 petition that calls for the FDA to phase out the use of medically important antibiotics in animals.

     They can also request that their local supermarkets carry antibiotic-free meat. The more consumers demand it, the more available and affordable it will be.

     And they can practice safe food handling—not letting the juices from raw meat get into the salad or other raw food, washing their hands after touching raw meat, and cooking their meat thoroughly. That can not only keep people from getting food poisoning. It can also prevent the spread of resistant bacteria like the kind that cause urinary tract infections.