TABLE 4.

Probit analysis of serial 10-fold dilution experiments using Treponema pallidum whole cell and in vitro 23S rRNA transcripts as challenges to determine RUO T. pallidum TMA limit of detection

Matrix	Challenge	Limit of detection value (%)	Result (lower limit, upper limit)	McFadden R2 coefficient
Specimen transport medium	T. pallidum whole cell	50	5 (3–8) cells/mL	0.911
		95	48 (24–143) cells/mL	0.911
	T. pallidum 23S rRNA in vitro transcript	50	221 (124–396) copies/mL	0.927
		95	5,707 (2,454–21,111) copies/mL	0.927
Rectal swab matrix	T. pallidum whole cell	50	3 (2, 5) cells/mL	0.985
		95	9 (6, 16) cells/mL	0.985
	T. pallidum 23S rRNA in vitro transcript	50	316 (none given) copies/mL	1
		95	421 (none given) copies/mL	1