Table 2.

Comparison of results from the identification of MTC in BACTEC cultures based on serpentine cording in smear, the ESAT-6/CFP-10 ICA, and a combination of serpentine cording in smear with the ESAT-6/CFP-10 ICA^a

Parameter	Identification of MTC in BACTEC cultures based on:
	Serpentine cording in smear	Positivity in ESAT-6/CFP-10 ICA	Intersection of serpentine cording in smear and positivity in ESAT-6/CFP-10 ICAc	Union of serpentine cording in smear and positivity in ESAT-6/CFP-10 ICAd
% Sensitivity	92.5	97	90.4	99.1
% Specificity	97.4	97.4	100	94.8
% PPV	97.8	97.9	100	95.9
% NPV	91.4	96.4	89.4	98.9
Likelihood ratiob	35.6	37.3	INe	19.1

^aThe data are from identifications of MTC in the 603 BACTEC cultures shown in Table 1.

^bLikelihood ratio = sensitivity/(1 − specificity).

^cThis indicates that both serpentine cording in smear and positivity in the ESAT-6/CFP-10 ICA were required in order to identify the culture to contain MTC.

^dThis means that either serpentine cording in smear, positivity in the ESAT-6/CFP-10 ICA, or a combination of both alone was sufficient in order to identify the culture to contain MTC.

^eIN, infinite.