Developers of the medicine, called Zyvox, say it is the first example of what they call the first new class of antibiotics in more than three decades. The drug appears effective against bugs that have grown resistant to all other medicines, including vancomycin, now the drug of last resort for lingering infections.
"There is a crying need for new antibiotics" for use against common but potentially deadly infections, said Dr. Jack Remington of Stanford University.
Zyvox works only against gram-positive bacteria, so-called because of the way they turn purple when stained. More than half of all serious infections treated in hospitals worldwide are gram positive. These include staph, strep and enterococci bacteria that cause pneumonia and infections of the skin, bloodstream and urinary tract, among other things.
Often these infections are caught while patients are in the hospital for other things. They tend to be resistant to many of the standard antibiotics in use since the 1950s.
About 5,000 patients have been treated so far with Zyvox, most of them in a variety of studies. However, the drug has also been given to 550 patients who could not use other antibiotics. Dr. Carol Kauffman of the Veterans Affairs Medical Center in Ann Arbor, Mich. said the drug cleared up the infection in three-quarters of them.
Researchers presented the results of several large studies with the drug Monday at a conference sponsored by the American Society for Microbiology. Its maker, Pharmacia & Upjohn, plans to seek approval for Zyvox from the U.S. Food and Drug Administration and other regulatory agencies around the world by the end of the year.
Zyvox is likely to be reserved for extremely ill patients, especially those with bugs resistant to older drugs. It will join another new antibiotic, Rhone-Poulenc Rorer's Synercid, which was approved by the FDA last week. Although available for the first time in the United States, Synercid is one of a class of antibiotics that has long been used in Europe as an additive to animal feeds.
Developers say Zyvox is entirely new. Because the drug will be different from anything that bacteria have encountered before, resistance should be rare, at least at the start.
"We believe that resistance will be very slow to emerge," said Dr. George Eliopoulos of Brigham and Women's Hospital in Boston. However, at least three cases of Zyvox resistance have already been seen during experimental use.
Zyvox, known generically as linezolid, is the first of a class of drugs called oxazolidinones. Dr. Donald Batts of Pharmacia & Upjohn said the last entirely new category of antibiotics was the quinolones, discovered 35 years ago.
Written By Daniel Q. Haney