Positive Xpert MTB/RIF Ultra Tests by SR Incubation Time

(SR 2:1)

Spiked CFU/mL

None (n = 16)

7.5 minutes (n = 16)

15 minutes (REF) (n = 16)

n (%)

(# Trace)

Avg

Ct Value

(Range)

n (%)

(# Trace)

Avg

Ct Value

(Range)

n (%)

(# Trace)

Avg

Ct Value

(Range)

10¹

2/4

(50%)

32.1

(32.1)

4/4

(100%) (3)

28.1

2/4

(50%)

27.2

(24.3 - 30.1)

10²

3/4

(75%) (1)

26.2

(26.2)

3/4

(75%)

30.8

(26 - 35.3)

3/4

(75%)

28.2

(24.3 - 33.4)

10⁴

4/4

(100%)

21.5

(20 - 23.2)

3/4

(75%)

18.1

(16.8 - 19.4)

4/4

(100%)

24.1

(18.8 - 26.9)

10⁶

4/4

(100%)

18.1

(16.3 - 18.4)

4/4

(100%)

17.6

(16.1 - 17.9)

4/4

(100%)

17.9

(17.4 - 18.6)