A new study by scientists at the University of Liverpool
documents, for the first time, how the ability of bacteria to swap genetic
material with each other can directly affect the emergence and spread of
globally important infectious diseases.
Known as 'horizontal gene transfer', this phenomenon is
understood to have played a role in developing the global antimicrobial
resistance (AMR) crisis. However, the dynamics of AMR transfer through
bacterial populations and its direct impact on human disease is poorly
understood.
To learn more about this relationship, a team of researchers
from the University of Liverpool, Wellcome Trust Sanger Institute and Public
Health England, combined epidemiological information from cases together with
whole genome sequencing analysis of bacteria from those cases.
The study, which is published in Nature Communications, looked
at three epidemics in England of the globally important diarrheal pathogen
Shigella between 2008 and 2014.
The findings found that English epidemics of these
typically-rare pathogens were associated with resistance to the antibiotic
azithromycin, and that many of the co-circulating Shigella strains carried the
azithromycin resistance genes on the same plasmid.
Plasmids are small circular DNA molecules that can be
transferred horizontally between bacteria. They contain the bacterium's genetic
material but are separate from the cell's chromosomal DNA.
By combining this genomic information from the different
Shigella strains with the epidemiological information about the outbreaks, the
researchers were able to demonstrate that the transfer of the plasmid was
facilitating new epidemics.
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Posted by Dr. Tim Sandle