Life
Haiti: Genomes of cholera bacteria confirm epidemic originated from single source – UN peace keepers
They sequenced the genomes of 23 different Vibrio cholerae isolates from Haiti that represent multiple PFGE “fingerprint” patterns and were taken from a variety of locations and at various time points during the epidemic.
When compared with the genome sequences of Vibrio cholerae strains from around the world, the Haiti isolates and three Nepal isolates are tightly related, forming a monophyletic group to which no other genome sequences belong.
This result indicates that “Nepalese isolates are the closest relatives to the Haiti strain identified to date, even when placed into a phylogeny with a larger collection of isolates representing recent cholera epidemics,” write the authors. This means that the outbreak originated from a single introduction of bacteria, and PFGE variants arose from gradual evolution of the organisms, not from any secondary introduction.
The Haiti strains also have a limited ability to acquire new genes through the process of transformation, by which genetic material is picked up from other bacteria or from the environment. There is some evidence that transformation is an important mechanism for bacteria to acquire the necessary abilities to adapt to a particular environment, so the fact that the Haiti strains are deficient in this respect raises the question of whether they will be able to adapt to life in Haiti or if they might go extinct once the epidemic has ended.
The Haiti isolates belong to a type of Vibrio cholerae called “Atypical El Tor” strains, a group that, in locations in Asia and Africa, has managed to acquire multidrug resistance and enhanced virulence traits that result in higher infection rates and harsher symptoms. The authors argue that to avert larger and more difficult to treat outbreaks of cholera, it is necessary to track the ongoing and unpredictable evolution of the organism in Haiti and elsewhere with surveillance of Vibrio cholerae via tools like whole genome sequencing.
About mBio®: mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.
The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM’s mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.
Source: American Society for Microbiology
