Word: bacterium
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Dates: during 1990-1999
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When a microbe replicates itself over many generations, mutations in the DNA that forms the organism's genetic blueprint can sometimes make it safe from an antibiotic. If, for example, the drug kills the bacterium by latching onto a specific molecule on its cell wall, a change in that molecule could make it impossible for the antibiotic to stick to its target. It's something like the protect-the-perimete r strategy used by defenders of ramparts on medieval fortresses. In other cases, says Neu, the bacteria develop enzymes capable of destroying the antibiotics and even molecular pumps that expel...
...Once a bacterium has a protective combination of genes, they are duplicated every time the bacterium reproduces itself. Moreover, the microbe can pass its genetic shield to a different strain of bacteria through a process called conjugation, the bacterial equivalent of sex. In addition to exchanging DNA in the form of chromosomes, conjugating bacteria can swap smaller snippets of DNA called plasmids. Like viruses, plasmids make exceedingly effective shuttles for carrying drug-resistant traits from one bacterium to another...
...emergence of TB strains that are resistant to standard medication. In last week's Nature, researchers from Hammersmith Hospital in London and from the Pasteur Institute in Paris report they have uncovered the genetic reason behind this dangerous trend. They have discovered that common forms of the TB bacterium bear a gene that makes it susceptible to the antibiotic isoniazid -- a gene that is missing in drug-resistant strains. The finding could lead to improved diagnostic tests that will help doctors treat people with drug-resistant TB before they can pass the infection on to others...
...accountant's son who excelled in Greek and Latin in college during the German occupation, Montagnier is no stranger to adversity. He faced it again in 1990, when he supported a controversial theory that mycoplasma, a bacterium-like organism, is the trigger that turns a slow-growing population of AIDS viruses into mass killers. According to Montagnier, the explosion of sexual activity in the U.S. during the 1970s fostered the spread of a hardy, drug-resistant strain of mycoplasma. HIV, meanwhile, lay dormant in Africa. The AIDS epidemic began, Montagnier speculates, when the two microbes got together, perhaps in Haiti...
...like symptoms in patients who test negative for HIV. The cause is unknown: it could be a new version of HIV (two are already known) or an evolved form of an existing one. It could be a completely different sort of virus. It could even be some sort of bacterium, or perhaps an environmental factor. Scientists believe they have already isolated a new virus in patients with this mock AIDS, but their work needs to be confirmed. Such a virus could contaminate blood supplies undetected, but because scientists could develop new blood tests quickly, the danger is minimal...