TABLE 2.

Susceptibility of MTBC strains in liquid cultures to PZA at 37°C and 28°C, at neutral and acidic pH^a

Strain	Phenotype	Inoculation density G+C content (bacteria/ml)	PZA DST results by tube type and temp
			37°C				28°C
			MGIT G&D tubes		MGIT low-pH tubesb		MGIT G&D tubes		MGIT low-pH tubes
			Result	TtP4 (control/+PZA) (days)	Result	TtP (control/+PZA) (days)	Result	TtP (control/+PZA) (days)	Result	TtP (control/+PZA) (days)
ATCC 27294 (H37Rv)	S	1.0 × 104	R	7/5	S	8.5/22.5	S	14/Nc	S	12/N
ATCC 25177 (H37Ra)	S	1.1 × 104	R	7/3	S	7/10	S	10/12	S	13/N
ATCC 35801	S	1.0 × 103	R	5/3	S	5/18	S	10/N	S	10/N
BD-201	Moderate Rd	3.3 × 102	R	6/4	S	7/15.5	S	10/25	S	10/N
ATCC 35828	R	4.3 × 103	R	5/3	R	5/3	R	8.5/5	R	8.5/5
DIS529	R	4.7 × 103	R	7/5	R	8.5/6	R	10/7	R	11/8.5

^aMTBC, M. tuberculosis complex.

^bMGIT PZA tubes (with or without PZA) are indicated here as “MGIT low-pH tubes” to avoid confusion.

^cN, both duplicates remained negative at day 26.

^dNormally classifies as susceptible in MGIT PZA testing.