Establishment of an <i>in vivo</i> -based assay using a silkworm infection model for phenotypic evaluation of antimicrobial drug combinations against <i>Mycobacterium abscessus</i>

<i>Mycobacterium abscessus</i> exhibits high intrinsic drug resistance, requiring combination therapy. We developed a silkworm (<i>Bombyx mori</i>) infection model as a whole-organism, <i>in vivo</i>-based platform for quantitative, outcome-based evaluations of antimicrobial combinations. The system, examined using clarithromycin-amikacin and imipenem-cefoxitin combinations, showed interaction profiles that were qualitatively consistent with those observed <i>in vitro</i>. This rapid, reproducible, and ethical assay enables reliable phenotypic assessments of synergistic or antagonistic effects and may facilitate the evaluation and prioritization of antimicrobial combination regimens in preclinical studies.