Antibiotics in Jeopardy - Special Feature

Nutrition Action Healthletter, March, 2002 by Tamar Barlam

Q: Why do bacteria become resistant to antibiotics?

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 drags 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.