ANTIMYCOBACTERIAL SUSCEPTIBILITY TESTING - PRESENT PRACTICES AND FUTURE-TRENDS

Along with the worldwide renewed interest in tuberculosis, the high in cidence of nontuberculous disease in HIV-infected patients and the con tinuing problem of disease caused by rapidly growing mycobacteria, the re has been a renewed interest in mycobacterial susceptibility testing . This renewed interest stems from the needs both to provide accurate, reliable and timely susceptibility test information for the managemen t of patients infected with these mycobacteria and to identify new and more effective antimycobacterial agents. indeed, many new agents have already been identified and are currently used to treat these infecti ons, but the conventional susceptibility testing methods, in many inst ances, have not been adequately evaluated for these new agents. Perhap s the time has come to give consideration to abandoning such time-hono red practices and criteria as the proportion method, the 99 % threshol d, and ''critical concentrations''. New methods of susceptibility test ing are in various stages of development and many of these methods hav e advantages and improvements over the existing methods. There is an i ncreased understanding of the pathobiology of mycobacterial infections and an increased understanding of the pharmacokinetics of antimycobac terial agents and the mechanisms of action and resistance. This articl e gives an overview of the present practices and an assessment of the current needs and potential for the near future of antimycobacterial s usceptibility testing.