Figure 3. Acquired tolerance to pyocins can be overcome by treating with a range of pyocins.

(a) Activity of pyocins S5, AP41 and L1 against WT P8, P8AP41T (a pyocin AP41 tolerant P8 strain) and P8AP41T* (P8AP41T recovered from untreated control mice shown in b). Purified protein at 200 μg ml⁻¹ was spotted onto a growing lawn of bacteria. Clear zones indicate pyocin cytotoxicity. (b) Bacterial counts for mice infected with P8AP41T and treated 1 h post-infection with pyocins (75 μg). Pyocin treated mice survived to 24 h. No colonies were recovered from pyocin S5 treated mice. Bars represent Mean ± SEM. *Denotes statistical significance for comparison of treatment versus control by a one-sided Mann-Whitney U test with Bonferroni correction applied. (c) P8 infected mice treated 1 h post-infection with pyocin combinations (7.5 μg of each pyocin); pyocin treated mice survived to 24 h. Bacterial counts were determined by CFU counts from homogenised lungs. Bars represent Mean ± SEM. *Denotes statistical significance for comparison of treatment versus control by a one-sided Mann-Whitney U test with Bonferroni correction applied.