Efficacy of lytic phage cocktails on staphylococcus aureus and pseudomonas aeruginosa in mixed-species planktonic cultures and biofilms

Legesse Garedew Kifelew, Morgyn S. Warner, Sandra Morales, Nicky Thomas, David L. Gordon, James G. Mitchell, Peter G. Speck

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27 Citations (Scopus)
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The efficacy of phages in multispecies infections has been poorly examined. The in vitro lytic efficacies of phage cocktails AB-SA01, AB-PA01, which target Staphylococcus aureus and Pseudomonas aeruginosa, respectively, and their combination against their hosts were evaluated in S. aureus and P. aeruginosa mixed-species planktonic and biofilm cultures. Green fluorescent protein (GFP)-labelled P. aeruginosa PAO1 and mCherry-labelled S. aureus KUB7 laboratory strains and clinical isolates were used as target bacteria. During real-time monitoring using fluorescence spectrophotometry, the density of mCherry S. aureus KUB7 and GFP P. aeruginosa PAO1 significantly decreased when treated by their respective phage cocktail, a mixture of phage cocktails, and gentamicin. The decrease in bacterial density measured by relative fluorescence strongly associated with the decline in bacterial cell counts. This microplate-based mixed-species culture treatment monitoring through spectrophotometry combine reproducibility, rapidity, and ease of management. It is amenable to high-throughput screening for phage cocktail efficacy evaluation. Each phage cocktail, the combination of the two phage cocktails, and tetracycline produced significant biofilm biomass reduction in mixed-species biofilms. This study result shows that these phage cocktails lyse their hosts in the presence of non-susceptible bacteria. These data support the use of phage cocktails therapy in infections with multiple bacterial species.

Original languageEnglish
Article number559
Number of pages16
Issue number5
Publication statusPublished - 18 May 2020

Bibliographical note

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


  • Biofilm
  • Efficacy
  • Fluorescence
  • Mixed-species culture
  • Phage cocktail therapy
  • Planktonic culture
  • Pseudomonas aeruginosa
  • Staphylococcus aureus


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