Abstract: Objective  To evaluate the effect of different sputum processing methods on the results of Lowenstein-Jensen（L-J）medium culture.  Methods  198 sputum specimens from suspected tuberculosis (TB) patients were collected, in which 99 samples were smear-positive and the others were smear-negative. Each sputum specimen was performed L-J medium culture simultaneously using the simple method and the centrifugal method,in which there were 5 following centrifugal conditions to be simultaneously used: 3000×g for 15 min, 3000×g for 8 min, 3000×g for 25 min, 2000×g for 15 min, 5000×g for 15 min.  Results  Of 198 sputum specimens, 126 were culture-positive, in which 97 originated from smear-positive sputa, and 29 originated from smear-negative sputa. The positive rates for the simple method and centrifugal method (3000×g for 15 min) were 93.65%（118/126）and 96.03%（121/126）.The average culture time for the simple method ［(20±8.56) days］ was 2 day shorter than that for centrifugal method［(22±9.10) days］. Of 125 culture-positive specimens by the centrifugal method, the positive rates at 5 centrifugal conditions mentioned above were 96.03%(121/126), 89.68%(113/126), 95.24%(120/126), 92.06%(116/126) and 96.03%(121/126), respectively.  Conclusion  The sensitivity of L-J medium culture by the simple method was similar with the centrifugation method. The simple method has the advantages of simple operation, lower contamination rate, shorter culture time, and was adaptable to be used widely. The centri fugal force and centrifugal time of the centrifugal method had some effect on the positive rate of culture.

Key words: Mycobacterium tuberculosis, Specimen handling, Sputum, Culture media, Bacteriological techniques