Regimen comprising clarithromycin, clofazimine and bedaquiline is more efficacious than monotherapy in a mouse model of chronicMycobacterium aviumlung infection

Abstract

Mycobacterium avium, a leading non-tuberculous mycobacterium (NTM) pathogen, causes chronic pulmonary infections, particularly in individuals with underlying lung conditions or immunosuppression. Current treatments involve prolonged multi-drug regimens with poor outcomes and significant side effects, highlighting the urgent need for improved therapies. Using a BALB/c mouse model of chronicM. aviumpulmonary disease, we evaluated the efficacy of individual antibiotics— clarithromycin, clofazimine, and rifabutin—and combination regimens including clarithromycin+bedaquiline and clarithromycin+clofazimine+bedaquiline. Clarithromycin demonstrated potent bactericidal activity, reducing lung bacterial burden by 2.2 log10CFU, while clofazimine transitioned from bacteriostatic to bactericidal, achieving a 1.7 log10CFU reduction. Rifabutin was bacteriostatic againstM. aviumMAC 101 but ineffective against MAC 104. The triple-drug regimen of clarithromycin+clofazimine+bedaquiline was the most effective, achieving a 3.3 log10CFU reduction in bacterial load, with 98% clearance within the first week and continued efficacy over eight weeks. Gross pathology confirmed these results, with granulomatous lesions observed only in untreated or rifabutin-treated mice. Combination therapy demonstrated enhanced efficacy compared to monotherapy. The findings underscore the potential of oral clarithromycin+clofazimine+bedaquiline or clarithromycin+clofazimine regimen as a promising therapeutic strategy forM. aviumpulmonary disease.