A Method for Generation Phage Cocktail with Great Therapeutic Potential

Abstract

BackgroundBacteriophage could be an alternative to conventional antibiotic therapy against multidrug-resistant bacteria. However, the emergence of resistant variants after phage treatment limited its therapeutic application.Methodology/Principal FindingsIn this study, an approach, named “Step-by-Step” (SBS), has been established. This method takes advantage of the occurrence of phage-resistant bacteria variants and ensures that phages lytic for wild-type strain and its phage-resistant variants are selected. A phage cocktail lytic for Klebsiella pneumoniae was established by the SBS method. This phage cocktail consisted of three phages (GH-K1, GH-K2 and GH-K3) which have different but overlapping host strains. Several phage-resistant variants of Klebsiella pneumoniae were isolated after different phages treatments. The virulence of these variants was much weaker [minimal lethal doses (MLD)>1.3×109 cfu/mouse] than that of wild-type K7 countpart (MLD = 2.5×103 cfu/mouse). Compared with any single phage, the phage cocktail significantly reduced the mutation frequency of Klebsiella pneumoniae and effectively rescued Klebsiella pneumoniae bacteremia in a murine K7 strain challenge model. The minimal protective dose (MPD) of the phage cocktail which was sufficient to protect bacteremic mice from lethal K7 infection was only 3.0×104 pfu, significantly smaller (p<0.01) than that of single monophage. Moreover, a delayed administration of this phage cocktail was still effective in protection against K7 challenge.Conclusions/SignificanceOur data showed that the phage cocktail was more effective in reducing bacterial mutation frequency and in the rescue of murine bacteremia than monophage suggesting that phage cocktail established by SBS method has great therapeutic potential for multidrug-resistant bacteria infection.

Therapeutic Potential of Staphylococcal Bacteriophages for Nasal Decolonization of &lt;i&gt;Staphylococcus aureus&lt;/i&gt; in Mice

“…Here, we examined phage K alone, and together with 44AHJD as a cocktail, for activity against S. aureus isolates that represented highly virulent, antibiotic-resistant, and genetically diverse strains. This established that the therapeutic potential of phages is improved as part of a cocktail, which supports previous literature reports [33,36].…”

Phage Therapy: a Step Forward in the Treatment of Pseudomonas aeruginosa Infections

“…The combination of two or more phages with different host ranges in a single suspension-a phage cocktail-has been reported to be more effective than the use of a single phage alone (63)(64)(65). Accordingly, Hall et al studied the effect of using one, two, or four phages, either sequentially or simultaneously, against P. aeruginosa PAO1 planktonic cultures (66).…”

Characterization and genome sequencing of a Citrobacter freundii phage CfP1 harboring a lysin active against multidrug-resistant isolates

“…Therefore, the antibacterial effect of CfP1 proved to be efficient to reduce Citrobacter populations to residual numbers up to 8-h incubation period. Inhibition on a longer term or even prevention of phage-resistant phenotypes could be achieved by combining phages (cocktail) that exploit different mechanics of infection (e.g., bacterial receptors) (Gu et al 2012). …”