That itch, that burn, constantly feeling like you have to pee — a lot of people are familiar with the symptoms of a urinary tract infection.

It’s a very common medical complaint, said Dr. David Patrick, an infectious disease specialist and acting lead of the B.C. Centre for Disease Control. It’s even, he said, the second-most-frequent reason women are prescribed antibiotics, behind respiratory infections.

The problem is, those antibiotics don’t always work.

The bacteria that cause urinary tract infections, like other bacteria, are becoming resistant to some of the drugs once used to treat them.

Data from LifeLabs, a Canadian company that does medical laboratory testing, shows that in Toronto, only about 58 per cent of E. coli infections — the bacteria responsible for the vast majority of UTIs — are susceptible to the antibiotic Ampicillin.

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The antibiotic Septra was about 77 per cent effective, and Ciprofloxacin worked in about 85 per cent of cases, according to the LifeLabs data from 2018. Dr. Kevin Schwartz, an infectious disease physician at Public Health Ontario, said:

“I would say that almost all urinary tract infections are resistant to at least one type of antibiotic.” Tweet This

“It’s natural selection of the bacteria to respond to the antibiotics in their environment,” he said. “Like any Darwinian natural selection, they’re going to try to replicate and survive any way that they can. So as they’re exposed to antibiotics over time, the bacteria devise ways to survive and they may become resistant.”

That means that doctors might have to try more than one drug before they find something that works well on a patient’s infection.

This can have consequences for patients. Infections can spread to other organs, like the kidneys, and if left entirely untreated can cause sepsis — a potentially deadly condition. A recent study found that in the U.S., hospitalizations for UTIs increased by 52 per cent between 1998 and 2011.

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Another study of UTI patients in Quebec found that men and people who were recently hospitalized were more likely to have drug-resistant infections and that as people got older, they had a higher chance of an infection being resistant to Ciprofloxacin. Bacteria from people in different parts of the province also showed different patterns of drug resistance.

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But as the bacteria adapted, so did doctors, according to Patrick. Older antibiotics tended to be used for UTIs as well as other kinds of infections like respiratory ones, he said. So as patients were repeatedly exposed during various illnesses, bacteria developed resistance.

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Most minor bladder infections are now treated with nitrofurantoin or fosfomycin, he said. These antibiotics work more specifically in the urinary tract, and don’t last very long in the body, lessening the chance that bacteria will become resistant, he said.

Now, he said, effectiveness rates for some of those older antibiotics are starting to creep back up. And, bacteria don’t seem to be adapting as well to these newly prescribed drugs, so their effectiveness remains high.

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That doesn’t mean we’re entirely in the clear, though. Data collected by Public Health Ontario has shown an increase in some types of resistance in the bacteria that typically causes UTIs over the last decade, Schwartz said.

“It looks like it’s levelled out over the last few years which is, I think, an overall good sign. But absolutely in certain areas, it continues to go up,” he said.

“You never say never,” Patrick said, particularly with a bug as tricky as E. coli. But, “with the change in practice in British Columbia, the likelihood of having a bug resistant to the drug your doctor gives you is a lot lower than it used to be.”