The incidence of nontuberculous mycobacterial diseases in the US is rising and has surpassed tuberculosis. Most notable among the nontuberculous mycobacteria is Mycobacteroides abscessus , an emerging environmental opportunistic pathogen capable of causing chronic infections. M. abscessus disease is difficult to treat and the current treatment recommendations include repurposed antibiotics, several of which are associated with undesirable side effects. In this study, we have evaluated the activity of omadacycline, a new tetracycline derivative, against M. abscessus using in vitro and in vivo approaches. Omadacycline exhibited an MIC 90 of 0.5 μg/ml against a panel of 32 contemporary M. abscessus clinical isolates several of which were resistant to antibiotics that are commonly used for treatment of M. abscessus disease. Omadacycline when combined with clarithromycin, azithromycin, cefdinir, rifabutin or linezolid also exhibited synergism against several M. abscessus strains and did not exhibit antagonism when combined with an additional nine antibiotics also commonly considered to treat M. abscessus disease. Concentration-dependent activity of omadacycline was observed in time-kill assessments. Efficacy of omadacycline was evaluated in a mouse model of lung infection against four M. abscessus strains. A dose equivalent to the 300 mg standard oral human dose was used. Compared to the untreated control group, within four weeks of treatment, 1 to 3 log 10 fewer M. abscessus colony forming units were observed in the lungs of mice treated with omadacycline. Treatment outcome was biphasic, with bactericidal activity observed after the first two weeks of treatment against all four M. abscessus strains.

M. abscessus disease incidence is increasing in the United States. This disease is difficult to cure with existing antibiotics.