Would bacteriophages kill resistant bacteria?

path4 at tifton.cpes.peachnet.edu path4 at tifton.cpes.peachnet.edu
Wed Mar 27 13:49:29 EST 1996

>The idea of using phage as an antimicrobial agent has been around since
>nearly the turn of the century. The problem is that resitance to phage
>tends to arise quite easily. Usually just a simple knockout mutation in
>the phage receptor. So phage resistant things would be expect to arise
>Second problem is that most phage are pretty highly strain specific,
>many phage of  E. coli K12 for example won't grow well in E. coli C or
>B strains (some do, some don't). Also you have restriction problem. Not
>all  E. coli strains have same restriction system, and the same is
>certainly going to be true for lots of other bacteria. So in order for
>this to really work well you would need to purify the resistant
>bacteria and find appropriate phage to propagate on it (and you would
>probably need multiple phages, not just one, to circumvent the phage
>resistance problem). I think the whole procedure would end up taking
>longer than the course of the infection.
>Michael Benedik
>Department of Biochemical Sciences
>University of Houston
>benedik at uh.edu
Phage treatments have been evaluated for the control of plant diseases
caused by bacteria.  In addition to the ratio of phage to bacterial
cells required, the growth phase of the bacterium is also a determining
factor in infection and lysis.  As an example, the spot method on an agar
overlay resulting in a lytic zone produced by the phage is restricted to
a relatively small diameter because the bacteria become insensitive in
later stages of growth.  If not, the phage should eventually lyse all
cells and clear the entire plate.  This does not happen.  Also, if I'm not
mistaken the dynamics of attachment and infection by phage with a susceptible
bacterium is affected by the growth medium and if it is on a solid surface
such as agar or in a liquid suspension?  Perhaps someone with more knowledge
about phage could verify or refute this information.
R.D. Gitaitis
Dept. of Plant Pathology
Coastal Plain Experiment Station
University of Georgia
Tifton, GA

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