Table 1.

Mean cycle threshold values generated by analysis of reconstituted BD GeneOhm Cdiff assay master mix and control material that was frozen at −70°C for up to 5 weeks^a

Specimen	Reconstituted reagent stored at −70°C	Mean CT ± SEM following storage interval of:
		0 wkb	1 wk	3 wk	5 wk
Positive lysatec	Master mix	30.51 ± 1.09	30.30 ± 1.00	30.29 ± 0.95	30.84 ± 1.14
Negative lysatec	Master mix	36.29 ± 0.21	35.99 ± 0.21	35.94 ± 0.23	35.99 ± 0.13
None	Positive controld	34.72 ± 0.08	34.55 ± 0.09	34.55 ± 0.09	34.43 ± 0.08e
None	Negative controld	36.04 ± 0.04	35.90 ± 0.05	35.84 ± 0.05f	35.81 ± 0.07f

^aMean cycle threshold values generated by analysis of reconstituted BD GeneOhm Cdiff assay master mix and control material frozen for up to 5 weeks at −70°C. The cycle threshold (C_T) values derived from negative lysates and negative-control material indicate internal control amplification.

^bFreshly reconstituted master mix.

^cTen lysates were incubated with frozen master mix from each storage interval.

^dTwenty replicates each of control material frozen for 1 week, 3 weeks, and 5 weeks.

^eSignificantly different (P = 0.02) from the value for freshly reconstituted positive control.

^fSignificantly different (P ≤ 0.009) from the value for freshly reconstituted negative control.