Analysis: Staph bug grows in community

By ED SUSMAN  |  Oct. 15, 2006 at 8:58 PM
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TORONTO, Oct. 13 (UPI) -- A deadly version of Staphylococcus aureus has become so widespread that it now shows up more often in patients coming into the hospital for treatment than among patients already being treated.

Worse, the arsenal of weapon to fight the bug - methicillin-resistant Staphylococcus aureus or MRSA - has been depleted, and the MRSA strains have begun to produce toxins that literally destroy the flesh.

"We now have people who come into the hospital and 40-50 percent of the time the community-acquired S. aureus is resistant to most of the antibiotics we have to fight it," David Gilbert, chief of infectious diseases at the Oregon Health and Science University, Portland, told United Press International.

Gilbert, past president of Infectious Diseases Society of America (IDSA), said that vancomycin - a drug of last resort that has been around for 60 years - and a couple of newer backups are available to fight the onslaught of resistant staph.

The spread of that microbe was illustrated by several reports Friday at the 44th annual meeting of the IDSA in Toronto, Canada. Doctors at Barnes-Jewish Hospital of Washington University at St. Louis tested every patient admitted to the hospital's intensive care unit over the past two years, getting specimens from more than 1,100 patients.

Keith Woeltje, associate professor of medicine at the university, reported that 33.1 percent of the patients carried S. aureus. Of the 376 specimens, 181 were organisms that were still sensitive to most antibiotics - but the other 195 specimens were MRSA.

Since these patients had specimens taken upon admission, it appears that the most prevalent staph microbe in the community in St. Louis is the resistant form of the bacteria.

Gilbert said that when MRSA was first reported 20 years ago it was confined to a few hospitals on the East Coast of the United States. "For a long time it was assumed that this was an organism that would only be found among hospitalized patients," he told UPI.

After the microbe spread around the world in the hospital setting, it began appearing in patients checking into the hospital.

"Now it either has become is or is becoming the most prevalent form of S. aureus in the community," he said, "but what's worse it that it is becoming more virulent."

Along the way, S. aureus has picked up from other microbes the ability to produce toxins -- toxins that are capable of rapidly destroying human tissue.

For many years, the scariest pathogen was Streptococcus A, the bacteria that caused sore throats and, rarely, the infection in skin caused a condition called necrotizing fasciitis -- the dreaded flesh-eating bacteria,

Now, it appears, the S. aureus toxins have given MRSA the ability to cause necrotizing fasciitis as well. The combination of infection, blocked blood vessels and decaying skin can cause disfigurement, amputation and even death.

In another study at the IDSA meeting, Lisa Young, an infectious diseases specialist at the University of Colorado Health Sciences Center, Denver, reported that in the past two years five of 30 cases of necrotizing fasciitis have been caused by S. aureus species. Necrotizing fasciitis remains rare, said Young, but community-acquired MRSA is on the rise.

Typically, she said, physicians assume the cause is Streptococcus A, and they treat the condition with a broad-spectrum antibiotic that is ineffective against MRSA.

"What we would recommend, if a patient comes in with what looks like necrotizing fasciitis and you live in a an area of high prevalence of community-acquired MRSA, that you would initiate antibiotic therapy for MRSA as part of the empiric treatment while waiting for cultures," Young said.

In addition to necrotizing fasciitis, Gilbert said he worries about the upcoming influenza season. Many people who contract viral influenza also come down with bacterial pneumonia, and MRSA can turn garden-variety pneumonia into necrotizing pneumonia that can destroys a person's lungs.

"We had one case of a 25-year-old man with influenza and necrotizing pneumonia," He told UPI. "That otherwise healthy young man died within 36 hours."

The outlook, however, isn't totally bleak. "We have really a lot of drugs in the pipeline to fight MRSA, including ceftobiprole which may be a cephalosporin that is active against resistant staph."

In another study presented Friday at IDSA, Gary Noel, senior director of clinical research and development for Johnson & Johnson, Raritan, NJ, described studies in which patients infected with MRSA did as well with the experimental ceftobiprole as they did with vancomycin, getting cure rates in the 85-90 percent range.

Gilbert said there are also some second generation vancomycin drugs in late development as well. "The pipeline is pretty rich," he said. "We are doing to need those drugs."

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