Fig. 5
From: Protein-inspired antibiotics active against vancomycin- and daptomycin-resistant bacteria
Mouse efficacy models. a MRSA thigh infection model. Colony forming units (CFU) in neutropenic mice infected in each thigh with MRSA, followed 2 h later by a single subcutaneous dose of antibiotic at concentrations indicated, with sacrifice and bacterial load determination in homogenised thighs at 24 h post treatment (26 h post infection): n = 10 (five mice per group, two thighs per mouse; errors are mean ± SEM). A significant difference was found between saline at 26 h and vancomycin 1 at 200 mg kg−1 (p < 0.0001), and vancapticin 19 at both 25 mg kg−1 (p < 0.0001) and 5 mg kg−1 (p = 0.0011). No statistical difference was found for vancomycin 1 at 25 mg kg−1 or vancapticin 24 at 25 mg kg-1 compared to saline. Vancapticin 19 at 25 mg kg-1 also showed a significant reduction compared to the initial t = 2 h baseline inoculum (p = 0.0014) whereas vancomycin 1 at 200 mg kg-1 was not statistically significant. Statistical analysis done using Graph Pad, 1-way ANOVA, Bonferroni post-test. b S. pneumoniae lung infection LD90. Survival of healthy mice infected with a lethal intratracheal dose of S. pneumoniae ATCC6301 followed 2 h later by a single subcutaneous dose of antibiotic at 25 mg kg-1 (n = 10 mice per group). c–e Bioluminescent MSSA intraperitoneal model. Neutropenic mice were injected intraperitoneally with 2.5 × 107 CFU bioluminescent MSSA Xen-29 (possessing a stable copy of the Photorhabdus luminescens lux operon on the bacterial chromosome) then treated after 0.5 h with subcutaneous doses of saline, 200 mg kg−1 vancomycin, 50 mg kg−1 daptomycin, 25 mg kg−1 19 or 25 mg kg−1 24 (n = 5 mice per group). c Changes in total flux levels. Variations in bioluminescence were measured at T = 0, 1, 3, 6 and 9 h, quantified with the IVIS Living Image software where the total flux (number of photons/second) was calculated by a user defined region of interest (ROI) covering the infection sites. The saline treated group showed a large increase in the total flux, particularly after 3 h (T = 3 h). Daptomycin, vancomycin and 19 treated groups showed a progressive reduction in the bioluminescence signal 1 h after inoculation, while the signal detected from 24 increased slightly. All antibiotic administered groups showed reduced bioluminescence signal at T = 9 h compared to immediately after inoculation (p < 0.001 for all groups; errors are mean ± S.D). d Changes in CFU per spleen after 9 h. Individual spleens were homogenised and diluted for plating. The calculated CFU/spleen counts for five mice are presented, along with the mean (black bar); errors are mean ± S.D. A significant difference was found between saline and vancomycin 1, daptomycin 4 and compound 19 (p < 0.001 for all groups). No statistical difference was found for 24 compared to saline, while this compound was found statistically less efficacious than 1 (p < 0.01), 4 (p < 0.001), and 19 (p < 0.001). Statistical analysis done using Graph Pad, 1-way ANOVA, Bonferroni post-test. e Bioluminescent images at T = 9 h. Bioluminescent imaging of infected mice at T = 9 h using Xenogen IVIS-200 Optical In Vivo Imaging System (PerkinElmer)
