In Vitro Synergism of Rifabutin with Clarithromycin, Imipenem, and Tigecycline against the Mycobacterium abscessus Complex

• DOI: 10.1128/aac.02234-18
• Publication Date: 2019-01-23T15:23:30Z
• Authors: Aristine Cheng; Yi-Tzu Tsai; Shu-Yuan Chang; Hsin-Yun Sun; Un-In Wu; Wang-Huei Sheng; Yee-Chun Chen; Shan-Chwen Chang
• Keywords: Rifabutin; Mycobacterium abscessus; Nontuberculous Mycobacteria; Tigecycline

Infections caused by the difficult-to-treat bacterium Mycobacterium abscessus are increasing in frequency. Rifabutin, contrast to rifampin, appears be active vitro against M. abscessus, especially clarithromycin-resistant strains. However, explorations for potential synergy between rifabutin and available antimicrobials currently limited. In synergism 10 was evaluated 31 mycobacterial strains checkerboard method. The fractional inhibitory concentration index (FICI) calculated each rifabutin-based combination. colony morphology recorded. Molecular methods determination of subspecies analysis macrolide resistance were performed sequencing secA1, rpoB, hsp65, erm(41), rrl genes. Rifabutin yielded an MIC50 16 mg/liter (range, 2 32 mg/liter) 26 clinical isolates (comprising 13 subsp. massiliense isolates) 5 reference strains, including ATCC 19977, bolletii BCRC 16915, 16916, chelonae 35752, peregrinum 700686. Significant synergism, classified FICI ≤0.5, demonstrated combinations imipenem 100% 69% isolates, significant tigecycline 77% isolates. Among 6 (MICs ≥ 8 combination clarithromycin synergistic. showed promising with first-line anti-M. agents, macrolide-resistant