[Bacteriologic basis for the treatment of tuberculosis]

To be fully effective, short-course chemotherapy for tuberculosis should take into account the slow growth rate, high oxygen requirement and high drug-resistant mutant emergence rate of Mycobacterium tuberculosis, as well as the type of the lesions observed and the specific activity of each antituberculous drug. Due to their unique sterilizing activities against bacilli that are not actively metabolizing, rifampicin and pyrazinamide are the key drugs for short-course chemotherapy. To prevent the selection of drug-resistant mutants and the occurrence of therapeutic failures, a combination of isoniazid, rifampicin, pyrazinamide and ethambutol should be given during the first two months of treatment. To kill persisting M. tuberculosis, and thus avoid posttreatment relapses, the isoniazid-rifampicin combination should be prescribed for à further four months.