Table 2.

Sensitivities, specificities, and positive and negative predictive values of the two PCR assays, using different approaches for the gold standard definition of B. fragilis infection

Gold standard definition	No. (%) of positive patientsa	PCR assay	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
Positive culture	7 (8.1)	RT-PCR	100.0	92.4	53.8	100.0
		C-PCR	87.5	93.7	54.5	98.7
Both PCR assays positive	11 (12.8)	RT-PCR	100.0	97.3	84.6	100.0
		C-PCR	100.0	100.0	100.0	100.0
Positive culture or both PCR assays positive	12 (14.0)	RT-PCR	100.0	98.6	92.3	100.0
		C-PCR	91.7	100.0	100.0	98.7
Positive culture or any one PCR assay positive	13 (15.1)	RT-PCR	100.0	100.0	100.0	100.0
		C-PCR	84.6	100.0	100.0	97.3
Positive culture and any one PCR assay positive	7 (8.1)	RT-PCR	100.0	92.4	53.8	100.0
		C-PCR	87.5	93.7	54.5	98.7

^aPatients who were considered positive for an infection due to B. fragilis, using the different gold standard definitions.