Laboratory assessment of sensitive molecular tools for detection of low levels of Echinococcus multilocularis-eggs in fox (Vulpes vulpes) faeces

Table 2 Results of the molecular analysis of the spiked fox faeces batches using four detection methods

DNA extraction method	PCR method	Whole data set						Samples with ≤ 15 eggs
DNA extraction method	PCR method	N	Se	Sp	PPV	NPV	AUC [95% CI]	N	Se	Sp	PPV	NPV	AUC [95% CI]
Egg sieving	Taq PCR	72	0.47	0.92	0.97	0.26	0.68 [0.57-0.79]	57	0.1	0.92	0.75	0.29	0.50 [0.40-0.60]
	EVA PCR		0.32	0.92	0.98	0.37	0.61 [0.51-0.71]		0.03	0.92	0.50	0.28	0.47 [0.38-0.56]
	mPCR		0.3	0.92	0.95	0.21	0.61 [0.51-0.70]		0.07	0.92	0.67	0.28	0.49 [0.39-0.58]
	CO1rtPCR		0.43	1	1	0.26	0.71 [0.65-0.77]		0.03	1	1	0.29	0.51 [0.48-0.54]
DNA Fishing	Taq PCR	72	0.65	1	1	0.37	0.85 [0.76-0.88]	61	0.40	1	1	0.40	0.70 [0.61-0.78]
	EVA PCR		0.77	1	1	0.46	0.88 [0.82-0.93]		0.60	1	1	0.50	0.80 [0.71-0.88]
	mPCR		0.02	1	1	0.17	0.50 [0.49-0.52]		0.0	1	0.0	0.29	0.5 [0.5-0.5]
	CO1rtPCR*		0.63	1	1	0.35	0.81 [0.75-0.87]		0.3	1	1	0.37	0.65 [0.56-0.73]

Values of Sensitivity (SE), Specificity (SP), Positive predictive values (PPV) Negative predictive values (NPV) and Area under the curve (AUC) for the different DNA extractions and detection methods tested in the study. The table is divided into the whole dataset of all samples (n = 144), and separately for samples containing low numbers of E. multilocularis eggs (<15) (n = 84). Detection was performed in triplicate, however, due to little DNA available, * CO1rtPCR on DNA-fishing was only possible in duplicate. Egg numbers added to each sample are available in Additional file 1: Table S2.

ISSN: 1756-3305