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.