For many young women, urinary tract infections are an occasional annoyance. They cause a few painful hours and many trips to the bathroom, but are soon dispatched with medication.
But they are something else again for the elderly. They send millions of women - and men - to the hospital every year and can kill if infection spreads to the kidneys or blood.
"Pneumonia and urinary tract infections (UTIs) are the biggest infectious reasons for admission to the hospital for older adults," said John Bruza, a geriatrician at Penn Medicine.
UTIs are feared enough that many hospitals are working harder to keep infections from starting on their watch by restricting use of urinary catheters. Infections acquired through catheters tend to be worse than those that patients get at home.
Because overuse of antibiotics can lead to tougher bugs, there is also a campaign to make sure doctors don't assume that vague symptoms in an older person started in the urinary tract.
"It's just more complicated for older adults," Bruza said.
Urinary tract infections are relatively common in young, sexually active women. Middle-aged women are less likely to get them. But more than 10 percent of women older than 65 and almost a third of those over 85 get a UTI each year, said Jennifer Khelil, vice president of medical affairs, physician services, at Virtua.
Rare in young men, the infections are more common in older men - though still not as frequent as in older women.
Older people are at greater risk for serious illness because UTIs are often further along before they are caught and because the elderly often have other health problems that make them more vulnerable.
"It speaks to just how medically fragile some of these folks can be," Khelil said.
Danielle Snyderman, a geriatrician with Jefferson Health, said she would treat a healthy 90-year-old with a UTI no differently from a much younger woman with the same condition. The problem is that most 90-year-olds are not that healthy.
In younger folks, UTIs have telltale signs, including burning during urination and a strong need to urinate even though very little is passed. Older people, who may already be feeling the need to urinate frequently for other reasons, are slower to notice urgency, the doctors said, and some may not feel the burning as intensely. Even fever, a sign that develops later in the infection, may be muted in the elderly because of weakened immune systems.
A UTI is often suspected when an elderly patient suddenly becomes weak or confused. That is a symptom, the doctors said, but there is a push to make sure there are also other physical symptoms of a bladder infection such as back or abdominal pain or fever.
Even urine testing is more complex in the elderly. Many older people often have relatively high levels of bacteria in their urine that may not be connected with symptoms.
To prevent over-treatment, Snyderman says, she does not order a urine test unless the right symptoms are present.
She follows recommendations outlined in the Choosing Wisely campaign, which is meant to reduce unnecessary medical treatment. The guidelines on UTIs, based on recommendations from the American Geriatric Society, were released in 2013.
Paul Mulhausen, a Des Moines, Iowa, geriatrician who oversaw those recommendations, said UTIs are clearly overdiagnosed, but he had no estimate for how often doctors are wrong.
He said it is "almost part of the culture of caring for dependent older people" for doctors to look at urine whenever older patients have cognitive changes. Ups and downs in functioning are common in people with underlying dementia, he said.
"I am suggesting that we often fail to take the diagnostic rigor that these circumstances warrant," he said.
"Building a culture of care around the urinary tract infection as the common cause of these kinds of changes has created its own set of problems around antibiotic overtreatment."
Other possible explanations for confusion or weakness include medications, strokes, other infections such as pneumonia or internal bleeding, Snyderman said.
Hormonal changes make older women more vulnerable to infection. The nature of urine itself changes with age, making it a less hostile environment for bacteria. Older men and women tend to have more trouble emptying their bladders as they age, and urine that sits longer in the bladder is more likely to be colonized by bacteria.
People who have had urinary infections before are at higher risk to have them again. UTIs are also more common in elderly people who are sedentary or incontinent or have diabetes, constipation and enlarged prostates.
Doctors said the best thing people can do to prevent urinary tract infections is drink plenty of water. They also tell patients to wipe from front to back when using the bathroom. It's a good idea to urinate before and after sex. The evidence on cranberry juice, long thought to prevent and treat infections, is mixed. Residents in institutional settings do better when the staff encourages them to use the bathroom on a regular schedule, Khelil said.
Hospitals are now required to report urinary tract infections that patients got while hospitalized. That has increased the incentives to reduce use of urinary catheters, Bruza said. He said catheters are needed for only a few reasons, including acute kidney problems, pressure ulcers around the sacrum and trouble emptying the bladder.
The devices were once widely used for long periods of time. Khelil said that during her training 20 years ago "we would catheterize people for weeks at a time and never give it a second thought."
Now medical teams at Penn and Virtua routinely discuss whether patients who have catheters still need them. Nurses have authority to remove them.
Does that mean adult diapers are better than catheters? In many cases, yes, Bruza said.
Mulhausen said doctors need to consider that treatments such as antibiotics and catheters can both help and hurt the elderly.
"Older people," he said, "are more vulnerable to the harm of our treatment. They require more thoughtful deliberation about risks and the benefits."