Table 2. Incremental yield of second specimen during follow-up culture examinations among Multi Drug Resistant Tuberculosis patients registered in 2008–09, India.

Total	1721
Culture results of first and second specimen
Negative-Negative	1226
Negative-Positive	18
Negative-Contaminated	4
Positive-Negative	28
Positive-Positive	390
Positive-Contaminated	4
Contaminated-Negative	8
Contaminated-Positive	11
Contaminated-Contaminated	32
Essential patterns of culture examination results
Positive-Any result	422
Non positive-Positive	29
Rest	1270
Number (Proportion) positive on any specimen	451 (26.2%)
Number (Proportion) positive on second specimen only: Incremental Yield	29 (1.7%)
95% Confidence Interval	1.0%–2.4%
Additional number of culture examinations to detect one positive result on second specimen	59
95% Confidence Interval	42–102