Evaluation of Target Specificity of Antibacterial Agents Using Staphylococcus aureus ddlA Mutants and D-Cycloserine in a Silkworm Infection Model

The availability of a silkworm larva infection model to evaluate the therapeutic effectiveness of antibiotics was examined. The 50% effective doses (ED(50)) of D-cycloserine against the Staphylococcus aureus ddlA mutant-mediated killing of larvae were remarkably lower than those against the parental strain-mediated killing of larvae. Changes in MICs and ED(50) of other antibiotics were negligible, suggesting that these alterations are D-cycloserine selective. Therefore, this model is useful for selecting desired compounds based on their therapeutic effectiveness during antibiotic development.