The role of the laboratory in the diagnosis and treatment of tuberculosis

Once he had revealed the presence of the tubercle bacillus in the sputum of tuberculosis patients, Robert Koch considered in 1882 that all that remained to be done was to 'disinfect' their sputum in order to suppress contagion and cure the patients. He was in fact right, but it was not until the discovery of the first antituberculous antibiotic - streptomycin (1944) - the arrival of isoniazid (1952) and the generalization of combined chemotherapy that it became possible to secure what he had hoped for: definitive 'disinfection' of the sputum of tuberculous patients. The role of the laboratory, including microscopy examination and culture of the sputum smears, is even more essential than before in the diagnosis of tuberculosis. It also extends to the choice of treatment, with the measurement of the sensitivity of the bacilli to the antibiotics and of the acceptability of the antibiotics by the patient, and is also concerned with the monitoring of treatment.