Study - Some Bacteria Turned "superbugs'' BEFORE Antibiotics
WASHINGTON (Reuters) - Cholera bacteria and their cousins swapped genes to develop stronger, new strains long before antibiotics were invented, researchers said Thursday.
They said this showed antibiotics were not the primary driving force that has caused bacteria to mutate into ever stronger forms. Antibiotic-resistant bacteria are becoming a bigger and bigger problem. They range from penicillin-resistant gonorrhea to super-strains of staphylococcus that cannot be killed by vancomycin, the strongest antibiotic available. One of the things that allows bacteria to develop resistance to antibiotics is their habit of meeting and exchanging genes with one another.
Didier Mazel and colleagues at the University of British Columbia studied the Vibrio genus of bacteria, which include the bug that causes cholera. They looked at samples of bacteria taken and preserved and dating back to 1888 -- before antibiotics were discovered. They identified a mechanism of gene-swapping called VCRs, Vibrio cholera repeat sequence clusters, in the older bacteria. They look and act just like integrons, which bacteria are known to use to develop resistance to drugs. Integrons are used by cells to ``read'' new genes and convert them into working genes. ``It is well established that integrons had a major role in the recent spread of multidrug resistance among Gram-negative bacteria,'' they wrote in their report published in the journal Science.
There are two kinds of bacteria, Gram-positive and Gram-negative. The Gram-negative strains are harder to kill because their cell walls are stronger. Obviously the older bacteria did not use the integrons to survive the onslaught of antibiotics, so they must have an older purpose, Mazel's team concluded. They said it was likely other kinds of bacteria have similar mechanisms. Studying them might shed light on how to battle emerging new superbugs.

Sightings HomePage