Drug sensitivity tests

This chapter focuses on drug sensitivity tests. For centuries, man has sought a cure for tuberculosis. Many bizarre yet ineffectual remedies were introduced and few physicians were willing to admit that they were powerless to modify the progress of this dread disease. As time went on, other antituberculous drugs were found, namely, ethambutol, ethionamide, thiacetazone, kanamycin, viomycin, capreomycin, cycloserine, pyrazinamide, and rifampicin. When considering the treatment of tuberculosis, it is convenient to regard the bacilli as belonging to certain functional groups. Methods for sensitivity testing are not designed merely to detect drug resistant mutants, as these will almost certainly be found. Instead, sensitivity testing is designed to show that the great majority of cells in a culture are as susceptible to a given drug as one or more known sensitive strains. The object of sensitivity testing is, therefore, to determine whether an isolate is as likely to respond to standard therapy as one or more known sensitive strains and the techniques used to attain this goal.