[Susceptibility to rifabutin and novel fluoroquinolones in Mycobacterium avium complex isolates from patients with sputum culture-positive pulmonary disease who are undergoing standard chemotherapy].

ABSTRACT

We investigated the susceptibility to conventional and newer antimycobacterial agents including rifabutin (RBT) and novel fluoroquinolones (NFQs) among 48 clinical Mycobacterium avium complex (MAC) isolates from patients with sputum culture-positive MAC disease who were undergoing standard chemotherapy. RBT and NFQs were superior to conventional agents because of higher rates of susceptibility and lower minimum inhibitory concentration. NFQs showed cross-resistance among quinolones. In contrast, RBT did not show cross-resistance to RFP. Most clarithromycin-resistant or rifampicin-resistant cases were susceptible to RBT and NFQs. In conclusion, RBT and NFQs possess good in vitro antimicrobial activity among clinical isolates of culture-positive pulmonary MAC disease, which suggests that a combination of such microbiologically active agents may improve clinical effectiveness more than standard chemotherapy regimens.