203. Development of Bacteriophage Cocktails with Expanded Host Range against MDR Pseudomonas aeruginosa
Session: Poster Abstract Session: Catheter-associated UTIs
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • Bacteriophage_IDSA_2013.pdf (794.6 kB)
  • Background: We found that co-coating catheters with a Pseudomonas (Psa)-specific bacteriophage and a biofilm of benign E.coli HU2117 synergistically prevented Psa biofilm formation on urinary catheters.  We are working on the development of broad host-range Psa-specific phage cocktails to use in this application. 

    Methods: Co-incubation of a mixture of 4 Psa-specific bacteriophage on 16 drug-resistant Psa isolates from human urine, was performed in cycles, with the supernatant (phage cocktail) from each cycle being used to inoculate the 16 Psa isolates in the subsequent cycle. Lytic assays on the original 16 strains (development strains) were performed using the phage cocktail from cycles 0, 5, 10, 15, and 20 to measure expansion of the phage host range.  These cocktails were also tested on 10 fresh Psa clinical isolates that had not been used in cocktail development (test strains). 10 plaques (subclones) isolated from each of the cycle 5 and 20 cocktails were subjected to host range and restriction analyses. 

    Results: Initially, 7 of the Psa development strains were sensitive to the 4 phages, and 9 were resistant (44% sensitive).  By cycle 5, 12 of the Psa isolates were sensitive to the phage cocktail (75%), 4 were resistant; % sensitivity did not increase with additional cycles.  On the 10 test strains, the initial combination of 4 phages lysed only a single Psa isolate (10%), while 9 Psa were resistant.  Susceptibility to the cocktail increased with cycle number until at cycle 20, 6/10 (60%) of the test Psa strains were sensitive to the cocktail. Restriction analysis of individual phage subclones isolated from cocktails did not detect chimeric patterns indicative of recombination. 

    Conclusion: The spectrum of Psa killing was expanded for both the development strains and the test strains after several cycles of co-incubation.  We did not detect genetic recombination in individual phage from the phage cocktails, suggesting that host range expansion occurs by mutation.  Alternatively, recombinants and/or mutants that contribute to the expanded host range may be minor components of the cocktail. The phage cocktail method can potentially be applied to other multi-drug resistant uropathogens.

    Mona Shiekh Sroujieh, MBBS1, Kershena Liao, BA2, Andrea Nash3, Robert Franklin Ramig, PhD3 and Barbara W. Trautner, MD, PhD2,3,4,5, (1)Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, (2)Baylor College of Medicine, Houston, TX, (3)Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, (4)Section of Infectious Diseases, Baylor College of Medicine, Houston, TX, (5)VA Health Services Research and Development Houston Center of Excellence, Michael E. Debakey VA Medical Center, Houston, TX

    Disclosures:

    M. Shiekh Sroujieh, None

    K. Liao, None

    A. Nash, None

    R. F. Ramig, None

    B. W. Trautner, None

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