Positive Xpert MTB/RIF Ultra Tests by SR Incubation Time

(SR 1:1)

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

3/4

(75%) (1)

30.8

(30.5 - 31.1)

3/4

(75%)

35.4

(30.2 - 38.8)

2/4

(50%)

28.7

(21.9 - 35.5)

10²

4/4

(100%) (1)

25.7

(24.5 - 26.7)

3/4

(75%)

29.2

(23.7 - 34.5)

3/4

(75%)

29.6

(22.5 - 37.7)

10⁴

4/4

(100%)

22.1

(19.6 - 25.4)

4/4

(100%)

21.8

(19 - 27.2)

4/4

(100%)

21.8

(17.9 - 24.1)

10⁶

4/4

(100%)

18.5

(18.3 - 18.7)

4/4

(100%)

18.1

(17.9 - 18.3)

4/4

(100%)

18.7

(18.3 - 19.6)