TY - CONF

T1 - Cytotoxicity and in vivo efficacy of a novel antimicrobial peptoid against Staphylococcus pseudintermedius

AU - Damborg, Peter Panduro

AU - Skindersø, Mette E

AU - Hansen, Paul Robert

AU - Bahnsen, Jesper Søborg

AU - Nielsen, Hanne Mørck

AU - Guardabassi, Luca

PY - 2012/8

Y1 - 2012/8

N2 - Objectives: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is emerging in dogs worldwide, and few or no treatment options are available for dogs infected by this pathogen due to its multi-resistance phenotype. The objective of this study was to evaluate cytotoxicity and investigate the in vivo efficacy of a novel peptoid (D2) previously shown to be effective against S. pseudintermedius in vitro. Methods: D2 was subjected to an array of cytotoxicity assays targeting proliferation, cellular stress, apoptosis and cell cycle in Jurkat cells. D2 was then formulated into a gel at a concentration corresponding to 10 X the highest MIC detected in S. pseudintermedius. The peptoid gel was tested using a murine skin infection model: DBA/2 mice were inoculated with an MRSP strain on a 3X2 cm scraped skin surface (day 0) followed by topical treatment twice daily with either D2 gel, placebo gel or fusidic acid ointment (day 1-3). Mice were euthanized on day 4. Affected skin was homogenized and CFU/ml was quantified by plate dilution on selective media. Results: D2 did not mediate apoptosis and showed limited effect on Jurkat cell viability and cell cycle at a concentration similar to that used in the murine model. Three days of D2 treatment did not have any significant effect on S. pseudintermedius counts in mice skin compared to placebo treatment. On the contrary, fusidic acid reduced bacterial counts significantly compared to D2 and placebo. Conclusion: S. pseudintermedius was used for the first time in this murine skin infection model and appeared to colonize well. The lacking effect of D2 in vivo could be due to either a too low concentration or an inhibitory effect of the gel formulation used. The next step will be to find the optimal concentration working in mice and assess toxicity for the chosen concentration.

AB - Objectives: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is emerging in dogs worldwide, and few or no treatment options are available for dogs infected by this pathogen due to its multi-resistance phenotype. The objective of this study was to evaluate cytotoxicity and investigate the in vivo efficacy of a novel peptoid (D2) previously shown to be effective against S. pseudintermedius in vitro. Methods: D2 was subjected to an array of cytotoxicity assays targeting proliferation, cellular stress, apoptosis and cell cycle in Jurkat cells. D2 was then formulated into a gel at a concentration corresponding to 10 X the highest MIC detected in S. pseudintermedius. The peptoid gel was tested using a murine skin infection model: DBA/2 mice were inoculated with an MRSP strain on a 3X2 cm scraped skin surface (day 0) followed by topical treatment twice daily with either D2 gel, placebo gel or fusidic acid ointment (day 1-3). Mice were euthanized on day 4. Affected skin was homogenized and CFU/ml was quantified by plate dilution on selective media. Results: D2 did not mediate apoptosis and showed limited effect on Jurkat cell viability and cell cycle at a concentration similar to that used in the murine model. Three days of D2 treatment did not have any significant effect on S. pseudintermedius counts in mice skin compared to placebo treatment. On the contrary, fusidic acid reduced bacterial counts significantly compared to D2 and placebo. Conclusion: S. pseudintermedius was used for the first time in this murine skin infection model and appeared to colonize well. The lacking effect of D2 in vivo could be due to either a too low concentration or an inhibitory effect of the gel formulation used. The next step will be to find the optimal concentration working in mice and assess toxicity for the chosen concentration.

M3 - Poster

Y2 - 22 August 2012 through 24 August 2012

ER -