One reason hospital-borne staph strains have evolved toward greater virulence—even deadliness—is their durability in the external environment. S. aureus is what Paul W. Ewald, an evolutionary biologist at the University of Louisville, calls a "sit and wait" pathogen. Though, unlike anthrax—another deadly and resilient agent—staph doesn't produce spores, it can persist under adverse conditions. It can survive for days or even weeks on fomites (objects contaminated by germs) such as computer keyboards, TV remotes and telephones. "In long-forgotten petri dishes in the lab, you could still scrape up live S. aureus," says Ewald.
And while flu and other infectious diseases require mobile hosts who sneeze or cough on the next victim, staph is happy to hitch a ride on unaffected nurses, doctors, aides, even visitors. Attendant-borne infections are like those carried by mosquitoes, says Ewald; both can maintain great virulence because they don't depend on host mobility for transmission.
To further complicate control of staph in the hospital, some strains now appear to be resistant to common hospital disinfectants. According to a 2002 article that appeared in Lancet Infectious Diseases, "In versatility of pathogenic strategies, numbers of virulence factors, and capacity to survive and multiply in a wide range of environments, S. aureus is unsurpassed by any other human pathogen."
That leaves American hospitals with a grievous problem: an insidiously spreading, often deadly disease that is very hard to treat. According to Perreiah, vancomycin, now the "drug of last resort," doesn't work all that well on MRSA infections, and resistance to it may be increasing. "If we lose vancomycin as a drug, we have limited options," he says.
As formidable an enemy as S. aureus has become, controlling its spread is not impossible, nor is there much mystery about what needs to be done. It won't be defeated by drugs but rather by interrupting the chain of its transmission in hospitals. The history of the bacterium—and its successful control in a few places—points the way.
First recognized during the late nineteenth century as a common cause of infection at surgical sites and wounds, staph had become the most frequent cause of hospital-borne infections by the 1930s. After a short-lived rout by antibiotics, particularly penicillin, during the 1940s—when S. aureus seemed to disappear—new, antibiotic-resistant staph strains began to emerge in hospitals all over the world. Penicillin quickly became ineffective; another drug, methicillin, was substituted, but resistance to that and several other widely used drugs soon followed. The resistant strain of S. aureus that has become the scourge of hospitals spread worldwide from its apparent origin in Europe during the early 1960s.
But since the 1970s, a strict no-tolerance policy has driven down infection rates in much of Europe—particularly in the Netherlands, Iceland, Norway, Denmark and Sweden—to extremely low levels. In Dutch hospitals, patients are routinely tested to see whether they're harboring MRSA strains. Even those who merely have transient bacteria in their nasal passages are isolated in single rooms, and visiting family members must be gowned and masked. Meanwhile, physicians and others who come in contact with affected patients are constantly monitored through nasal swabs to make sure they're not carrying the bacteria. Hospital workers in these northern European countries wash their hands often and use alcohol-based sanitizers, which are even more effective than soap and water—and easier on the hands. Floors and other surfaces are frequently disinfected.
In the United States, the PRHI has also begun to make measurable headway against MRSA. Inspired by former U.S. Treasury Secretary Paul O'Neill's success at improving worker safety when he was CEO of Alcoa, PRHI has adopted principles of the Toyota Production System in declaring a systematic war on MRSA. Like workers in Toyota plants, all employees in participating Pittsburgh-area hospitals—from physicians and administrators to aides and the cleaning crew—have been given the authority to take action whenever they spot a problem. And just as Toyota produces virtually defect-free vehicles, PRHI hospitals have sharply cut infection rates among patients.
According to Richard P. Shannon, chairman of the department of medicine at Allegheny General Hospital and an executive committee member of PRHI, 236 patients had documented MRSA infections during the three years preceding the MRSA initiative. Those infections cost the hospital $3.2 million, or almost $14,000 per patient. Patients with MRSA infections spent an average of 31 days in the hospital, and 49% were readmitted at least once for MRSA-related complications. Thirty-eight patients died.
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