New research shows a possible link between the bacteria that cause urinary tract infections in humans and bacteria found in food animals.

Furthermore, experts say health-care providers may not recognize these drug-resistant strains without lab testing.

Chobi DebRoy, director of Penn State's Gastroenteric Disease Center (GDC), said the researchers found strains of E. coli isolated from patients with urinary tract infections (UTIs) that were 95 percent similar genetically to strains isolated from cows.

"Our research showed that the strain that can cause UTIs may come from animal sources," DebRoy said. "This link was not established before."

She added that the GDC has about 60,000 strains of E. coli collected over the last 40 years, which made it possible to carry out this research.

DebRoy said researchers have not found this particular strain of E. coli in beef, but because it is found in cows, they assume it could get into the food chain.

"One could get an infection after eating beef that is raw or rarely cooked," she said.

About 85 percent of UTIs are caused by E. coli, and they are typically treated with antibiotics, said James Johnson, professor of medicine at the University of Minnesota and one of the researchers in the study.

The strains observed in the study were resistant to certain types of antibiotics, he added.

"The background [of this research] is that there have been observations made in the last few years that a substantial fraction of drug-resistant UTI cases are caused by a single strain of E. coli," Johnson said. "The strain had not really been seen prior to the 1990s as a significant player in UTIs."

Johnson said that while E. coli found in food animals were very similar to the ones isolated from humans with UTIs, the researchers did not find a single one that was a "dead ringer."

However, "we did see that the likelihood that these bacteria would have antibiotic resistance increased over the years, just like the ones we found in humans," he said. "The research clearly shows that some very similar bugs are found in animals and humans."

Johnson said the potential link is important to study because people need to use newer and costlier antibiotics in order to treat these drug-resistant UTIs.

"Increasingly, people are giving up on the laboratory testing," Johnson said. "It's not uncommon for doctors to prescribe antibiotics based on the symptoms alone, without doing a culture to find out what the bug was."

This is a problem because if the doctor guesses incorrectly about the resistance pattern of the bacteria, the treatment would be ineffective, causing the person to have symptoms longer, Johnson said.

JoAnna Moyer, director of the Women's Health Department at University Health Services (UHS), said there are three types of UTIs, and UHS usually does not do a culture if the patient has what is considered an acute uncomplicated infection, which is the most common.

" 'Acute uncomplicated' usually means that the symptoms have been there for less than seven days and there are no signs that the kidneys are involved in the infections," Moyer said. "Most of the time our first choice of antibiotic is effective, and the overwhelming majority will get better."

DebRoy said she thinks the healthcare system is efficient in taking care of UTIs.

Symptoms of UTIs include frequent and urgent urination, a burning sensation during urination and blood in the urine, Moyer said.

Moyer said that acute complicated UTIs have the same symptoms of acute uncomplicated UTIs, but are marked by having symptoms for more than seven days and a history of bladder infections.

Pyelonephritis occurs when the infection spreads to the kidneys, which can cause fever, nausea, chills and kidney pain, in addition to the usual UTI symptoms, Moyer added.

Ellen Nagy, UHS marketing manager, said that women are more likely than men to get UTIs because of their anatomy. There is a shorter distance between the urethra and bladder in women than in men, which makes it easier for the bacteria to travel.

For acute complicated UTIs and pyelonephritis, UHS does a culture to isolate the organism and a sensitivity test to find out which antibiotics are effective against the bug, Moyer said.

However, "it's safe to treat people who meet the criteria for an uncomplicated UTI without doing a culture, and it saves them a pretty significant expense," Moyer said. "Bladder infections are really common, and if we started doing a culture on everyone who showed symptoms, it would increase across the board the cost of healthcare enormously."

A urine culture and sensitivity test at UHS costs $47 for students, she said.