Correlation of the results of X-ray and sputum culture in tuberculosis prevalence surveys.

In the course of 6 tuberculosis prevalence surveys carried out in South Africa, 5477 persons were investigated by sputum culture and chest X-ray. The X-ray was reported to show evidence of tuberculosis in 723 cases, and of these the sputum culture was positive in only 100 (13.8%). The sputum culture was also positive in another 76 (1.5%) cases in which the chest X-ray was negative. The reasons for these discrepancies are discussed.