Pig-to-Human 'Superbug' May Be Due to Animal Antibiotics

TUESDAY, Feb. 21 (HealthDay News) -- Researchers who traced the evolution of a potentially deadly antibiotic-resistant bacteria strain that can jump from livestock to humans say their findings highlight the dangers of widespread antibiotic use in animal food production.

The international team of scientists studied methicillin-resistant Staphylococcus aureus CC398, also known as pig MRSA or livestock-associated MRSA, which most often infects people with direct exposure to swine or other livestock.

It's likely that MRSA CC398 originated as an antibiotic-susceptible strain in humans before it jumped to livestock, they said. Once in livestock, MRSA CC398 became a so-called superbug, resistant to two important antibiotics, tetracycline and methicillin, used to treat staph infections.

This resistance is likely caused by the widespread use of antibiotics in livestock to prevent infection and promote growth, said the authors of the study published online Feb. 21 in the journal mBio.

The findings reveal evolution in action, according to Paul Keim, one of the study authors and a professor and director of the Center for Microbial Genetics and Genomics at Northern Arizona University. He is also director of the pathogenic genomics division at the Translational Genomics Research Institute (TGen) in Phoenix.

"The most powerful force in evolution is selection. And in this case, humans have supplied a strong force through the excessive use of antibiotic drugs in farm animal production. It is that inappropriate use of antibiotics that is now coming back to haunt us," Keim said in a university news release.

This strain of MRSA was discovered less than a decade ago but appears to be spreading quickly, according to study lead author Lance Price, a university faculty member and director of the Center for Food Microbiology and Environmental Health at TGen.

"Our findings underscore the potential public health risks of widespread antibiotic use in food animal production," Price said in the news release. "Staph thrives in crowded and unsanitary conditions. Add antibiotics to that environment and you're going to create a public health problem."

More information

The U.S. Centers for Disease Control and Prevention has more about antibiotic resistance.

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Antibiotics no help against most sinus infections

NEW YORK (Reuters Health) - Antibiotics don't help fight most sinus infections, although doctors routinely prescribe them for that purpose, researchers said Tuesday.

The medications are known to fuel the evolution of drug-resistant bacteria and experts have grown increasingly worried about overuse.

That's a particular concern with sinus infections, because doctors can't tell if the disease is caused by bacteria or by a virus, in which case antibiotics would be worthless.

The new study, published in the Journal of the American Medical Association, found antibiotics didn't ease patients' symptoms or get them back to work any sooner than an inactive placebo pill.

"There is not much to be gained from antibiotics," said Dr. Jane Garbutt of Washington University School of Medicine in St. Louis, who led the work.

"Rather than give everybody an antibiotic hoping to find the ones with bacteria, our findings would suggest refraining from antibiotics and doing what we call watchful waiting," she told Reuters Health.

That involves keeping an eye on patients to see if they get better, but not using other drugs than over-the-counter painkillers.

People with sinus infections, also called acute sinusitis, have lasting and severe cold-like symptoms such as runny nose and pain around the eyes, the nose or the forehead.

"It's the fifth most common reason antibiotics are prescribed for adults," said Garbutt. "It's hard for doctors not to give an antibiotic because patients are so miserable and we don't have anything else to give them."

But it hasn't been clear whether the drugs actually work, and even the studies that have found some benefit see the majority of placebo-treated patients get better by themselves.

Garbutt and her colleagues used official U.S. guidelines to identify patients with sinus infections. They randomly assigned 166 adults to either placebo pills or a 10-day treatment with the antibiotic amoxicillin.

Based on patient ratings on a symptom scale known as the modified Sinonasal Outcome Test-16, or SNOT-16, the researchers found little difference between the two patient groups.

Using the aptly named scale, where 0 equals "no problem" and 3, a "severe problem," the antibiotic group rated their symptoms at 1.12 after three days, while the placebo group averaged 1.14. After seven days, there were signs of benefit from the antibiotic, but the effect was small and had vanished another three days later.

Neither were there differences in how many work days patients missed, how satisfied they were with their treatment, how often they relapsed or how much additional medical care they got.

After 10 days, 78 percent of the people on antibiotics and 80 percent of the placebo-treated people said they felt a lot better or no longer had symptoms.

Dr. Anthony Chow, an expert in infectious diseases at the University of British Columbia in Vancouver, Canada, said less than two percent of sinus infections are bacterial.

"Most cases are viral, and the vast majority don't require antibiotics," he told Reuters Health. "Antibiotics have been abused, so there is a need to be more cautious in prescribing them and to hold back."

But Chow said antibiotics still have a place.

He recently chaired a committee at the Infectious Diseases Society of America, which has developed guidelines to help spot infections that are more likely to be bacterial.

Those guidelines, still in press, recommend treating only patients whose symptoms last for at least 10 days and keep worsening; who are severely sick with high fever and other symptoms; or who improve and then get worse again.

SOURCE: http://bit.ly/A4EKuo JAMA, February 14, 2012.

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Antibiotics no help against most sinus infections: study

(Reuters) - Antibiotics don't help fight most sinus infections, although doctors routinely prescribe them for that purpose, according to a U.S. study.

Researchers whose work was published in the Journal of the American Medical Association found that antibiotics didn't ease patients' symptoms or get them back to work any sooner than an inactive placebo pill.

Antibiotics are known to fuel the evolution of drug-resistant bacteria and experts have grown increasingly worried about overuse.

This is a particular concern with sinus infections, because doctors can't tell if the disease is caused by bacteria or by a virus, in which case antibiotics are useless.

"There is not much to be gained from antibiotics," said Jane Garbutt of Washington University School of Medicine in St. Louis, who led the study.

"Rather than give everybody an antibiotic hoping to find the (patients) with bacteria, our findings would suggest refraining from antibiotics and doing what we call watchful waiting," she told Reuters Health.

That involves keeping an eye on patients to see if they get better, but not using drugs other than over-the-counter painkillers.

People with sinus infections, also called acute sinusitis, have lasting and severe cold-like symptoms such as a runny nose and pain around the eyes, nose or forehead.

"It's the fifth most common reason antibiotics are prescribed for adults. It's hard for doctors not to give an antibiotic because patients are so miserable, and we don't have anything else to give them," said Garbutt.

Garbutt and her colleagues used official U.S. guidelines to identify patients with sinus infections. They randomly assigned 166 adults to either placebo pills or a 10-day treatment with the antibiotic amoxicillin.

Based on patient ratings on a symptom scale known as the modified Sinonasal Outcome Test-16, or SNOT-16, the researchers found little difference between the two patient groups.

Using the scale, where 0 equals "no problem" and 3 a "severe problem," the antibiotic group rated their symptoms at 1.12 after three days, while the placebo group averaged 1.14.

After seven days, there were signs of benefit from the antibiotic, but the effect was small and had vanished another three days later.

After 10 days, 78 percent of the people on antibiotics and 80 percent of the placebo-treated people said they felt a lot better or no longer had symptoms.

Fewer than two percent of sinus infections are bacterial, said Anthony Chow, an expert in infectious diseases at the University of British Columbia in Vancouver, Canada.

"Most cases are viral, and the vast majority don't require antibiotics," he said.

"Antibiotics have been abused, so there is a need to be more cautious in prescribing them and to hold back."

But he said that antibiotics still do have a place and recently chaired a committee at the Infectious Diseases Society, which has developed guidelines to help spot infections that are more likely to be bacterial.

Those guidelines, still in press, recommend treating only patients whose symptoms last for at least 10 days and keep worsening, who are severely sick with high fever and other symptoms, or who improve and then get worse again. SOURCE: http://bit.ly/A4EKuo

(Reporting from New York by Frederik Joelving at Reuters Health; editing by Elaine Lies and Bob Tourtellotte)

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