Early bactericidal activity of antituberculosis agents
The assessment of the early bactericidal activity (EBA) of antituberculosis agents by measurement of viable colony-forming units (CFU) of Mycobacterium tuberculosis in sputum of patients with smear-positive pulmonary tuberculosis is now an established methodology for the early clinical evaluation of a new antituberculosis agent. EBA establishes the daily rate at which a specific dose of a new agent reduces the number of viable bacilli present in sputum during the first 14 days of treatment. Simultaneous study of pharmacokinetics offers the opportunity to evaluate the relationship between dosage, serum concentration, efficacy and specific host or mycobacterial factors relevant to the agent under investigation. Recently the clinical efficacy of several new classes of antituberculosis agents has been confirmed by EBA studies, and these have shown these agents to have a relatively slow onset of detectable activity; by contrast, the newer fluoroquinolones have an EBA over days 0-2 comparable to that of isoniazid and may prove valuable in the prevention of resistance amongst companion drugs. Recent experience has shown that time to detection of metabolic activity in liquid media reflects drug activity in a manner comparable to that of CFU counting and needs further exploration. Copyright © 2011 S. Karger AG, Basel.