Figure 4

Efficacy of LysRODI preventive treatment in a mastitis mouse model. CD1 lactating mice at breastfeeding day 10 were treated by intramammary administration of 24 μg of LysRODI and challenged 90 min later with 5 × 10⁴ CFU/mice of S. epidermidis or S. aureus. Mice inoculated with PBS or mock buffer were used as controls of staphylococcal infection. (A) Macroscopic aspect of R4-R5 mammary glands of mice treated with (I) treated 24 μg/mouse of LysRODI or (II) PBS and infected with S. aureus Sa10. Red arrows indicate symptoms of edema, hyperemia and changes in color of an infected mammary gland. (B) Preventive efficacy of LysRODI against S. aureus and S. epidermidis mammary glands infections in CD1 mice, determined by the mean ± standard deviation of individual log₁₀ CFU/mammary gland. White symbols are Lys-RODI treated mice; black symbols are untreated mice, inoculated with either PBS or mock sterile buffers; circles and squares represent, respectively, S. aureus and S. epidermidis challenged mice. The number of CFU was determined in each R4-R5 mammary gland, at 18 h post-challenge. Statistical comparison of means was performed by ANOVA and post-hoc PLSD tests: ^**p < 0.001 and ^***p < 0.0001 vs. control (PBS or mock).