Drug-Resistant Staph May Get Nastier
Experts Call for Increased Efforts to Halt MRSA
Aug. 31, 2006 - It may already be too late to bring the rapidly spreading drug-resistant staph bug known as MRSA under control.
That's the gloomy warning from a review article and editorial -- both by leading infectious disease experts -- in the Sept. 2 issue of The Lancet.
MRSA is methicillin-resistant Staphylococcus aureus. The bacteria are resistant to several important antibiotics. At least for now, some other antibiotic drugs still kill it.
But MRSA already is the most common skin infection in U.S. cities. Worldwide, anywhere from 2 million to 53 million people are carriers.
Staph in general, and MRSA strains in particular, are very tricky bacteria. It's easy for them to gain drug resistance. Staph bugs often infect the skin, but can infect other areas of the body as well.
The bug was first seen in hospitals. But new MRSA strains have arisen in the general community and, while on the loose, have become more easily transmissible -- and, in some places, more virulent.
Now these strains are going into hospitals, where they wreak havoc on vulnerable people -- and even on health care workers.
"The MRSA situation in hospitals, which still remains out of control in many countries, could potentially become explosive," warn Hajo Grundmann, MD, of the Netherlands National Institute for Public Health and the Environment, and colleagues, in The Lancet article.
An editorial accompanying the Grundmann article offers little solace.
""If we are going to act, we should do it now, before what is currently sporadic illness ... becomes epidemic, and commonly used antibiotics become useless," urges microbiologist Ian M. Gould, PhD, of Aberdeen Royal Infirmary, U.K.
Brief History of MRSA
Staph has been acquiring drug resistance ever since antibiotics were invented. In the 1950s, a penicillin-resistant staph bug called the 80/81 strain devastated hospital patients worldwide.
Normal staph causes potentially deadly blood infections in less than 3% of people carrying it. The 80/81 strain caused blood infections in 30% of carriers treated.
The invention of the antibiotic methicillin ended the reign of the 80/81 bug. But methicillin-resistant staph soon appeared.
That wasn't such a big surprise. The shock was that a change in a single genetic element gives methicillin-resistant staph -- MRSA -- resistance to multiple antibiotics.
Over time, MRSA has picked up more resistance genes. That was bad. But it was thought to happen only in hospitals, where there was more exposure to different antibiotics.
In the 1990s, however, it became clear MRSA strains were evolving outside hospitals. The bug appeared in communities -- such as indigenous Australians -- that had had little access to health care.
Other groups affected have been those likely to have greater levels of physical contact, such as incarcerated people, military personnel, and athletes.
These "community" varieties tend to have a nasty bit of genetic material called Panton-Valentine leukocidin, or PVL. Community MRSA causes skin and soft tissue infections -- giving such bugs the potential to become so-called "flesh-eating bacteria."
Community MRSA has caused this and other dangerous infections, including internal organ infections, joint infections, toxic shock syndrome, and severe pneumoniapneumonia.
Today, MRSA is the most common drug-resistant bug in North America, Europe, North Africa, the Middle East, and East Asia.