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. 2012 May 22;7(5):e37650. doi: 10.1371/journal.pone.0037650

Table 3. Yield of first and Incremental yield of the second and third serial sputum culture.

Observed and expected incrementalyield LJ MGIT LJ orMGIT
Observed yield from 1st sputum culture: 0.212 0.259 0.306
Observed yield from 2nd sputum culture: 0.042 0.119 0.069
Observed yield from 3rd sputum culture: 0.024 0.043 0.043
Total positives observed 43 60 62
Missed TB cases %¥
Positives missed by not doing a 2nd sputum culture 0.7 2.0 1.2
Positives missed by not doing a 3rd sputum culture 1.1 1.8 1.7
Total positives missed 1.8 3.8 2.9
Expected yield from 3 sputum cultures (Exp)π 44.8 63.8 64.9
Expected Yield (Fraction)†
Observed pattern (n) + missed TB cases/Exp 1.000 1.000 1.000
Expected from the first sputum culture‡1 0.805 0.690 0.801
Expected from second sputum culture ‡2 0.127 0.236 0.126
Expected from third sputum culture‡3 0.068 0.075 0.073

LJ (Solid culture) = Lowenstein Jensen, MGIT (Liquid culture) = Mycobacterium Growth Indicator Tube.

¥ = Number of estimated TB cases missed among those who never submitted the 2nd and 3rd sputum sample for culture, assuming a same proportion of TB cases as in those who submitted the 2nd and 3rd sputum for culture, respectively. † = The proportion of TB cases expected if each of the suspects had a complete set of three sputum cultures, Π = Total positives observed + total positives missed, ‡1 = Px/Exp, ‡2 = NPx + missed by second/ExP and ‡3 = NNP + missed by third/Exp.