I am a third-year PhD student at the University of Warwick, currently writing up my thesis. During the last three years, I worked on the development of phage therapy to treat canine skin infection due to Staphylococcus pseudintermedius, a coagulase-positive bacterium. Methicillin-resistant S. pseudintermedius (MRSP) causing postoperative infections and urinary tract infections in addition to skin infections emerged recently and studies have shown that successful MRSP clones are spreading very rapidly across the dog population. S. pseudintermedius has a high host specificity and does not usually colonize humans. However, zoonotic transmission from animal to humans sometimes occurs and MRSP has the ability to cause infections in humans.
Phage therapy where phages, the viruses of bacteria, are administered to cure an infection, can be an alternative treatment and an effective way to overcome the problem of resistance to antibiotics. It has been actively researched and developed at the beginning of the 20th century before the discovery of penicillin in 1928. Phage therapy has then been completely forgotten in western societies. It has regained attention in the last two decades as the situation of bacterial resistance in human and animal health gets worse and researchers seek for new effective treatments.
There are two types of phages: lytic phages, which lyse their host and release new viruses, and temperate phages, which have the ability to survive within their host (lysogeny) and occasionally enter the lytic cycle. Temperate phages are usually not regarded as appropriate for phage therapy but it is possible to mutate them so that they are no longer able to establish lysogeny, and able to infect and kill lysogens.
Contents of my thesis
The work undertaken over the last three years has resulted in the gain of knowledge about phages infecting S. pseudintermedius. This was done towards the general aim of this PhD project: developing phage therapy to treat canine skin infection caused by MRSP. The work was divided in four parts:
1. Isolation of both lytic and temperate phages from environmental samples and S. pseudintermedius strains respectively.
2. Characterization of the isolated bacteriophages with the objective to select the best candidate(s) for phage therapy.
3. The isolation of virulent mutants of S. pseudintermedius phages because the ones that were found during the project were all temperate.
4. The bioinformatic analysis of phage genomes to learn about their characteristics on the genetic level.
Prof. Emeritus David A. Hodgson
D dot A dot Hodgson at warwick dot ac dot uk
Prof. Elizabeth M. H. Wellington
E dot M dot H dot Wellington at warwick dot ac dot uk
Prof. Finn K. Vogensen
fkv at life dot ku dot dk
Dr. Arshnee Moodley
asm at sund dot ku dot dk