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Bacterium's Immunity to Powerful Drug Bodes Ill

Health: As one bug outsmarts the mighty antibiotic vancomycin, scientists fear more unstoppable organisms.

February 20, 1996|SHARI ROAN | TIMES HEALTH WRITER

Since it was launched in 1958, the antibiotic vancomycin has been considered the big gun against troublesome bacteria that ran roughshod over less potent antibiotics. Its manufacturer, Eli Lilly & Co., proudly touted it as "a drug before its time."

When doctors treating very ill patients wanted the ultimate protection against a wide range of bugs that could cause fatal infections, they would turn to vancomycin.

What no one expected in 1958, or even as recently as a few years ago, was that a bacterium would outsmart every antimicrobial, including mighty vancomycin, the so-called drug of last resort.

Such a bug has emerged, and it is producing plenty of anxiety in hospitals and acute-care nursing homes across the country. The organism is a gastrointestinal bacterium called enterococcus that was considered harmless until it began to mutate out of the reach of every drug, lastly vancomycin. First reported in Europe in 1988, vancomycin-resistant enterococcus has spread methodically westward; sporadic cases began cropping up in California in 1994.

And while vancomycin-resistant enterococcus is no Andromeda strain, its presence signals the ominous dawn of an era in which infectious diseases that once were put down easily with antibiotics could become incurable.

Outbreaks in Africa of the deadly Ebola virus have helped awaken the public to the threat of incurable infectious disease. But experts say that what the American public, and even their physicians, may fail to realize is that the problem is now at hand as common bacteria find ways to survive an arsenal of overworked and misused antibiotics.

"The general public is at greater risk of antibiotic-resistant organisms than some exotic thing like viral hemorrhagic fever," says Dr. Hildy Meyers, an Orange County Health Department epidemiologist. "Vancomycin is a last line of defense against some infections."

And that line is wavering. About 14% of all hospital-acquired enterococcal infections are now resistant to vancomycin, a twentyfold increase from 1989, according to a federal study of intensive care units.

Reducing the risk of vancomycin-resistant enterococcus, known as VRE, has become a priority at acute-care hospitals and nursing homes, where the bug can thrive because of a combination of circumstances: very sick patients, excessive use of top-flight antibiotics and highly infectious environments.

Three small outbreaks have been reported in Los Angeles-area health facilities since 1994, and sporadic cases have cropped up in Orange County. Nationally, every state has reported VRE, but the majority of outbreaks have been concentrated in the Northeast. Several facilities, including a hospital in New York state and an acute care nursing home in Santa Clara County in Northern California, acknowledge battling VRE outbreaks involving dozens of patients.

But public health officials say most hospital administrators are so sensitive to the fact that their facilities may be harboring an incurable organism that they are reluctant to acknowledge VRE cases.

For this reason, VRE and the threat that even more dangerous bacteria could become resistant to vancomycin have largely escaped notice--until recently.

Awareness increased last month, when the Journal of the American Medical Assn. dedicated an entire issue to emerging infectious diseases and antibiotic resistance.

"We need to call attention to the crisis we're in," says Dr. Donald A. Goldmann, an infectious diseases specialist in Boston who warned of the problem in the journal.

In California, health officials have had the dubious advantage of knowing that VRE was heading their way. "VRE has moved consistently westward," says Dr. John Rosenberg, an epidemiologist with the state Department of Health Services. He is attempting to track the increase in cases, improve laboratory testing methods and educate health officials. "We're doing much more [to prevent] it than any other state that I'm aware of. But whether it does any good, I don't know."

There is a reason for Rosenberg's pessimism: Enterococcus isn't easy to stop.

The organism lives silently in the intestinal tracts of most people, where it causes no illness. In some cases, it breaks into the bloodstream and becomes an infection. Even then, most healthy people with good immune systems fight it off.

Enterococcus becomes a problem when bloodstream infections occur in very sick individuals or those recovering from major surgery, whose immune systems already are overwhelmed. In these cases, an antibiotic is needed or the infection can greatly reduce the chances that the already-weakened patient will recover.

The crisis occurs when the patient--who already may harbor harmless enterococci--has acquired a strain that is vancomycin-resistant.

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