Résumé
Antibiotic resistance is becoming increasingly problematic for the
treatment of infectious disease in both humans and livestock. The
bacterium Pseudomonas aeruginosa is often found to be resistant to
multiple antibiotics and causes high patient mortality in hospitals.
Bacteriophages represent a potential option to combat pathogenic bacteria
through their application in phage therapy. Here we capitalize on previous
studies showing how evolution may increase phage infection capacity
relative to ancestral genotypes. We passaged four different phage isolates
(podoviridae, myoviridae) through six serial transfers on the ancestral
strain of Pseudomonas aeruginosa PAO1. We first demonstrate that repeated
serial passage on the ancestral bacteria increases bacteriophage infection
capacity on ancestral hosts and on those evolved for one transfer. This
result is confirmed when examining the ability of evolved phage to reduce
ancestral host population sizes. Second, through interaction with a single
bacteriophage for 24 hours, P. aeruginosa can evolve resistance to the
ancestor of that bacteriophage; this also provides these evolved bacteria
with cross-resistance to the other three bacteriophages. We discuss how
the evolutionary training of phages could be employed as effective means
of combatting bacterial infections or disinfecting surfaces in hospital
settings, with reduced risk of bacterial resistance compared to
conventional methods.