Word: bacterias
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Dates: during 1990-1999
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Before the coming of penicillin and other antibiotics, bacterial diseases simply ran their courses. Either the immune system fought them off and the patient survived or the battle was lost. But antibiotics changed the contest radically: they selectively killed bacteria without harming the body's cells. For the first time, potentially lethal infections could be stopped before they got a foothold...
Unfortunately, as Columbia University's Dr. Harold Neu observed in the journal Science, "bacteria are cleverer than men." Just as they have adapted to nearly every environmental niche on the planet, they have now begun adjusting to a world laced with antibiotics. It didn't take long. Just a year or two after penicillin went into widespread use, the first resistant strain of staph appeared. As other antibiotics came along, microbes found ways to resist them as well, through changes in genetic makeup. In some cases, for example, the bacteria gained the ability to manufacture an enzyme that destroys...
...medicine's worst nightmares is the development of a drug-resistant strain of severe invasive strep A, the infamous flesh-eating bacteria. What appears to make this variant of strep such a quick and vicious killer is that the bacterium itself is infected with a virus, which spurs the germ to produce especially powerful toxins. (It was severe, invasive strep A that killed Muppeteer Jim Henson in 1990.) If strep A is on the rise, as some believe, it will be dosed with antibiotics, and may well become resistant to some or all of the drugs...
...difference between animals and bacteria is that a new generation comes along every few years in large beasts -- but as often as every 20 minutes in microbes. That speeds up the evolutionary process considerably. Germs have a second advantage as well: they're a lot more promiscuous than people are. Even though bacteria can reproduce asexually by splitting in two, they often link up with other microbes of the same species or even a different species. In those cases, the bacteria often swap bits of genetic material (their DNA) before reproducing...
...picking up genes as well. The DNA can come from viruses, which have acquired it while infecting other microbes. Some types of pneumococcus, which causes a form of pneumonia, even indulge in a microbial version of necrophilia by soaking up DNA that spills out of dead or dying bacteria. This versatility means bacteria can acquire useful traits without having to wait for mutations in the immediate family...