Bugs Behaving Badly
Antibiotics are aging, and bacteria are learning to fight them off
Last month brought fresh evidence that while small, bacteria can certainly look out for themselves. Clostridium difficile, a microbe that can cause serious digestive illness and death in vulnerable patients in hospitals and nursing homes but rarely bothers healthy adults outside healthcare settings, was blamed by the federal Centers for Disease Control and Prevention for doing just that in four states. Like many other germs, it apparently had mutated, under pressure from antibiotics, into a toxic new strain.
As if that wasn't bad enough, a couple of weeks later, the Journal of the American Medical Association suggested that we had aided the resourceful C. difficile by dosing ourselves with pills such as Pepcid and Prilosec that prevent severe heartburn, or reflux, by lowering the acidity of the stomach's gastric juices. That acidity, noted the authors, keeps the upper part of the digestive tract bug free. By reducing the acidity, the pills lowered the barrier.
Unbeatable. Such news was just the latest in a string of misadventures that illuminate the uncommon adaptive power of bacteria. Until about 25 years ago, most disease-causing germs stood little chance against the stream of antibiotics that had emerged from laboratories during the 1940s and '50s. Top researchers at large pharmaceutical companies truly believed that the days of infectious disease were over.
But the flow of unique new classes of antibiotics ebbed and died in the 1960s. Resistant strains of microbes that had crumbled obediently at the touch of drugs like vancomycin appeared. Now some 2 million hospital patients a year get bacterial infections; about 90,000 of them die. The National Institute of Allergy and Infectious Diseases estimates that more than 70 percent of the bacteria that cause these infections are resistant to one or more antibiotics. That complicates care, inflating the cost of treating an infected patient. And so reports such as these are piling up:
Military service members injured in Iraq and Afghanistan increasingly are coming home with Acinetobacter baumannii, a potent microbe that causes pneumonia and blood infections, in their wounds. Plucked straight from soil or water, the bug is naturally resistant, often to multiple antibiotics. Sometimes physicians have to turn to coliston, a drug rarely used since the 1960s because of the high chance of injuring the kidneys and nervous system.
Gonorrhea used to be easily treatable with penicillin, but the bacterium reponsible, Neisseria gonorrhoeae, long ago shrugged it off. Now the newer quinolone class of antibiotics such as Cipro and Floxin, which became the drugs of choice, are being defeated in the United States and in Australia, Canada, Great Britain, and Hong Kong. It has gotten so bad, J. Todd Weber, director of the CDC' s office of antimicrobial resistance, wrote in a JAMA editorial in November, that the usefulness of quinolone drugs to treat and control gonorrhea "is being lost worldwide because of increasing resistance."
Resistant strains of bacteria usually confined to hospitals are finding their way into local communities. In 2003 and 2005, studies fingered Staphylococcus aureus, a microbe that is blamed for many serious heart and lung infections in hospitals and nursing homes and is resistant to the methicillin class of anti-biotics, as the cause of outbreaks of skin abscesses in high school wrestlers in Indiana, members of a Colorado fencing club, and five players on the St. Louis Rams football team.
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