Using Reduced Inoculum Densities of Mycobacterium tuberculosis in MGIT Pyrazinamide Susceptibility Testing to Prevent False-Resistant Results and Improve Accuracy: A Multicenter Evaluation

Table 3

Summary of categorical MGIT PZA susceptibility test results stratified by possible outcome and inoculation method.

Inoculation; method	Susceptibility test result
	Resistant				Susceptible
	Number/category		Percent of total		Number/category		Percent of total
	True	False	True	False	True	False	True	False
BD	52	64	44.8	55.2	186	2	98.9	1.1
A	42	17	71.2	28.8	226	11	95.4	4.6
C	42	8	84.0	16.0	230	9	96.2	3.8

Percentages correspond to the positive predictive value of a resistant result being true-resistant. Percentages correspond to the negative predictive value of a susceptible result being true-susceptible. 18 of the false-susceptible results occurred in isolate 17. The remaining 4 occurred in isolate 14, all in the same laboratory.