Antibiotic Resistance Still a Major Public Health Threat

FRIDAY Oct. 30, 2009 -- The emergence of antibiotic-resistant bacteria continues to present a major public health problem, said scientists gathering at one of the world's largest infectious diseases meetings Friday.

Chief among the concerns are resistant gram-negative bacteria and bacteria that appears to be infecting younger and otherwise healthier people. The troubling trend is compounded by another concerning fact: a paucity of new antibiotics coming down the pipeline, they added.

"Antibiotic development is dying, and we are running out of drugs. We have organisms that are already resistant to every antibiotic we can throw at them," said Dr. Brad Spellberg, a member of the Infectious Diseases Society of America's (IDSA) Antimicrobial Availability Task Force and an assistant professor of medicine at UCLA. "What will be increasingly seen in the coming decade is a dramatic decline in the availability of new antibiotics, which are desperately needed."

Spellberg spoke during a teleconference from the IDSA annual meeting in Philadelphia.

Antibiotic resistance, even to new drugs, has become such an issue with nasty gram-negative bacteria that clinicians have had to reach back into the arsenal, resurrecting a drug that hadn't been used much in 20 years, polymyxin.

But now pathogens are becoming resistant to that drug as well, analysis of lab samples at one New York City hospital showed.

"Although the prevalence of gram-negative bacteria resistant to polymyxin is currently at a relatively low level of around 6 percent, we noted over a relatively short two-year timeframe that the prevalence of resistance to that agent increased by about 50 percent," said Dr. Jason Kessler, lead author of a study detailing the findings, which are scheduled to be presented at the meeting.

"In addition, amongst all of the isolates we evaluated, more than 30 percent demonstrated resistance to at least five classes of antibiotics, meaning that most of those isolates or most of those bacteria probably could only be treated with polymyxin, suggesting the prevalence of very highly drug-resistant gram-negative infection is on the rise in our facility," added Kessler, who is a clinical fellow in the division of infectious diseases at Columbia University in New York City.

Other infections are targeting younger people and moving from hospitals into the community and back into hospitals.

Clostridium difficile, a common hospital infection, for instance, is now hitting people who have not been in the hospital. These patients have a median age of 53, versus a median age of 70 in hospitals, said Dr. Ghinwa Dumyati, lead author of this study and an associate professor of medicine at the University of Rochester School of Medicine and Dentistry.

It's not clear exactly where these community cases are coming from, but many of the people, although healthy, were taking antibiotics, suggesting that the medications "are still an important factor in the development of C. difficile in the community," Dumyati said.

Similarly, methicillin-resistant Staphylococcus aureus (MRSA) is causing severe illness in younger, healthy people, although the infections are not resulting in either death or long hospital stays, according to another study. The fact that the patients were younger and healthier may have decreased the risk of death," said study author Dr. Fernanda Lessa, of the U.S. Centers for Disease Control and Prevention.

MRSA infections in emergency rooms have increased 211 percent between 2000 and 2008, another study found. The incidence in multi-drug-resistant Acinetobacter baumannii, a gram-negative bacteria, is also on the rise, largely in the hospital, said researchers from Henry Ford Hospital in Detroit.

On the more positive side, a meta-analysis of studies on extremely drug-resistant tuberculosis found that newer versions of antibiotics known as fluoroquinolones did seem to help people with this infection.

These findings are ironic, said Dr. Neil Fishman, chair of the IDSA Antimicrobial Resistance Work Group and director of the Antimicrobial Management Program for the University of Pennsylvania Health System. "Fluoroquinolones have been implicated in causing a lot of problems with resistance and, to some extent, fluoroquinolones are the schoolyard bully of resistance," he said. Proper "stewardship," or prudent use of antibiotics would help curb this trend, he added.

Experts at the teleconference also expressed hope that the attention being focused on H1N1 (swine) flu right now could act as a "wedge" issue, to further spotlight the antibiotic problem. For the moment, however, H1N1 is eclipsing the resistance issue, even though many people succumbing to H1N1 also end up with bacterial infections.

More information

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

Posted: October 2009


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