A closer look at bacterial insurgents

American troops in Iraq are battling on yet another front, one as ancient as war itself, yet as modern as the post-penicillin era. Over 240 wounded soldiers have been afflicted with bloodstream infections of the antibiotic-resistant bacterium Acinetobacter baumannii. Left unchecked, this bacterium causes urinary tract infections, pneumonia, meningitis, sepsis and even death.

Using DNA sequencing technology from 454 Life Sciences, a Branford, Conn., biotech company, Michael Snyder, Ph.D., the Lewis B. Cullman Professor of Molecular, Cellular and Developmental Biology, and colleagues analyzed the bacterium’s entire genome.

In the March 1 issue of Genes and Development, Snyder’s group revealed that a surprising 17 percent of A. baumannii’s genetic material originated in other microorganisms. Over half of these “alien islands” contain genes that are critical to the bacterium’s ability to harm humans.

The study shows that the organism has gained a tactical advantage by incorporating foreign DNA. Understanding these evolutionary adaptations will bolster the antibiotic armamentarium.