Comparative analysis of Mycobacterium abscessus clinical isolate virulence using an invertebrate infection model

Abstract

AbstractAimsMycobacterium abscessus causes chronic skin infections, lung diseases, and systemic or disseminated infections. We investigated the quantitative evaluation of the virulence of M. abscessus clinical isolates by calculating the LD50 using a silkworm infection model.Methods and ResultsM. abscessus subsp. abscessus cells were injected into the hemolymph of silkworms. Silkworms died within two days post-infection with M. abscessus subsp. abscessus when reared at 37°C. Viable cell numbers of M. abscessus subsp. abscessus increased in the hemolymph of the silkworms injected with M. abscessus subsp. abscessus. Silkworms were not killed following injections with heat-killed M. abscessus subsp. abscessus cells. The administration of clarithromycin, an antibacterial drug used for the treatment of the infection, prolonged the survival time of silkworms injected with M. abscessus subsp. abscessus. The LD50 values of seven clinical isolates were determined using the silkworm infection model and differed by up to nine-fold.ConclusionsM. abscessus proliferation is required to kill the silkworms and that the virulence of M. abscessus clinical isolates can be evaluated by the silkworm infection model.Significance and Impact of the StudyThe silkworm infection model with M. abscessus is useful for estimating the virulence of the clinical isolates in a short period.