Researchers Explore "the Belly of the Beast" of Antibiotic Resistance

Seven years ago, a young man known to science only as Patient X was hospitalized with a staphylococcus aureaus -- or staph -- infection. At first he responded to antibiotics, but the baceria became immune. In just twelve weeks he was dead.

At the time, doctors preserved staph specimens taken at each stage of his demise. Scientists recently sequenced the genomes of the bacteria, producing the first-ever step-by-step, gene-level description of how antibiotic resistance emerges.

Every time the patient took his medicine, the antibiotics killed the weakest bacteria in his bloodstream. Any cell that had developed a protective mutation to defend itself against the drug survived, passing on its special trait to descendants. With every round of treatment, the cells refined their defenses through the trial and error of survival.
"It means that during a normal course of treatment there is an evolutionary revolution going on in your body," said Stanford
University biologist Stephen Plaumbi, author of "The Evolution
Explosion: How Humans Cause Rapid Evolutionary Change."

These resistant microbes, all disease-producing organisms spawned by the original infection, quickly accumulated 35 useful mutations. Each one altered a molecular sensor or production of a protein.

The researchers say that the findings might be used to find ways of disabling the genes responsible for adaptation and mutability. But while that might be the next stage in our battle against bacteria, something tells me it won't be the last.

Related Wired coverage here.

Evolution at Work: Watching Bacteria Grow Drug Resistant [Wall Street Journal]

Image: NIH*