By Rita Rubin
WebMD Health News
Reviewed by Brunilda Nazario, MD
April 29, 2015 -- If you've ever had one (or a dozen) urinary tract infections, you might not be surprised to learn that they're the most common bacterial infections in the United States.
What you might not know is that doctors are running out of oral antibiotics to treat such infections, which account for nearly 10 million annual visits to doctors' offices or hospital emergency departments.
That's happening as the bacteria causing them become more resistant to the medicines used to treat them. Antibiotic resistance in general is on the rise worldwide, but one especially troubling example is the rise in resistant strains of E coli, the bacteria that cause more than 80% of UTIs.
In some cases, doctors have had to resort to older, less-effective antibiotics. In other cases, they've had to put a catheter into patients' arms to give antibiotics through a vein, because no medications taken by mouth worked. Sometimes doctors have had to ask the FDA for permission to use a medicine that the agency has not yet approved.
"Bacteria are smarter than humans," says Lilian Abbo, MD, an infectious disease specialist at the University of Miami. "When you challenge bacteria with an antibiotic, maybe the first time the bacteria will say, 'Oops, we've never seen this,' and the antibiotic will kill them."
But familiarity with antibiotics breeds contempt in bacteria, which can develop ways to make them ineffective. Resistance can even spread among bacteria, enabling them to fend off antibiotics they'd never previously been exposed to.
Sometimes, doctors must try two, three, or even four antibiotics to vanquish stubborn UTIs, Abbo says. As an infectious disease specialist, she sees patients who keep getting UTIs. Those fourth-line medications are often "broad-spectrum" antibiotics, meaning they also wipe out the good bacteria in the gut that help with digestion and your immune system.
"We're basically using a grenade to kill a mosquito," Abbo says. "The mosquito became resistant to all the repellents and keeps biting you."
One study of E. coli taken from urine samples of U.S. patients found that the greatest increases in resistance between 2000 and 2010 were for the antibiotics Cipro (3% to 17%) and Bactrim (18% to 24%). (Bactrim is also called Sulfatrim and Septra).
A third of women will get a UTI that needs to be treated with an antibiotic by age 24. Half of all women get at least one UTI in their lifetime. If you're one of them, you're familiar with the symptoms -- the painful peeing and the frequent, urgent feeling that you have to go to the bathroom. Untreated, UTIs can lead to a kidney infection that could cause serious or permanent damage.
UTIs in Pregnancy
Because of safety concerns, pregnant women have even more limited choices when it comes to treating UTIs, which are common during pregnancy. Along with kidney infections, UTIs can also cause preterm labor. At the same time, some antibiotics prescribed for the infections could hurt the unborn baby, says Catherine Eppes, MD, MPH, an obstetrician-gynecologist at the Baylor College of Medicine in Houston.
In a paper published in March in the American Journal of Obstetrics & Gynecology, Eppes and colleague Steven Clark, MD, described a 31-year-old patient who was 12 weeks pregnant and having fever, nausea, and pain due to a UTI.
She'd been treated 2 weeks earlier for another UTI with Macrobid, a commonly prescribed older antibiotic. This time, she was hospitalized and prescribed Rocephin. On the third day, tests showed that her infection was resistant to that antibiotic. She was switched to one given through a vein. After 2 days in the hospital, she was discharged but had to keep getting the antibiotic by IV for 12 more days at home.
"We seem to be getting more and more women admitted to our hospital service with these infections," Eppes says. "Antibiotic resistance, especially in UTIs, is definitely an emerging and important issue."
Doctors have tended to shy away from prescribing Macrobid to treat UTIs in older women, because they're more likely to have less kidney function, which is thought to make the drug less effective.
But a new study of nearly 200,000 older women who'd been treated for UTIs concluded that kidney function made no difference in whether Macrobid was effective. The problem, researchers reported Monday in the Canadian Medical Association Journal, was that Macrobid didn't work as well as some other antibiotics.
Doctors decide which medication to prescribe based on the patient and her infection, but how well the kidney's working doesn't need to be a consideration, says co-author Amit Garg, MD, PhD, a kidney specialist at Western University in London, Ontario.
It Really a UTI?
In some cases, no antibiotic is effective against postmenopausal women's symptoms, because they don't actually have a UTI.
"Sometimes you will treat them, but such women come back in time and time again with those symptoms," suggesting that their symptoms are due to age-related hormonal changes, not an infection, says her colleague, Thomas Hooton, MD. He's a University of Miami infectious disease doctor who specializes in treating people who keep getting UTIs.
Hooton is a co-author of the Infectious Disease Society of America's guidelines for treating garden-variety UTIs in women.
Don't Go Looking for Trouble
One thing contributing to antibiotic resistance in the treatment of UTIs is that some people with no symptoms are getting prescriptions, Hooton says.
For example, healthy women typically provide urine samples at checkups so the doctor can look to see whether the samples have protein or sugar, either of which could be signs of underlying problems. Sometimes, though, white cells, a sign of inflammation, turn up in the test results, and doctors go ahead and prescribe an antibiotic, Hooton says, even though having bacteria in the urine without any symptoms isn't a disease. They mistakenly think that symptoms will arise if the apparent infection isn't quashed, he says.
In people without symptoms, antibiotics are appropriate only for pregnant women whose urine suggests they might have a UTI, Hooton says. As for everyone else who doesn't have symptoms, "don't even look for [an] infection."
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