TABLE 3.

Validation of genus and species classification by FT-IR, given as probability for correct identification of strains (repeated determinations)^a

Organism	nref	All strains			External strains
		nval	Identification (%)		nval	Identification (%)b
			Correct	Incorrect		Correct	Incorrect
Yersinia (genus level)	32	183	92.1	1.3	151	91.5	1.5
Yersinia (species level)	101	183	77.9	2.0
Y. enterocolitica	48	113	79.9	2.6	65	78.7	3.9
Y. ruckeri	6	12	73.7	1.6
Y. pseudotuberculosis	5	11	84.3	1.4
Y. bercovieri	11	11	96.7	0
Y. rohdei	2	2	100	0
Y. intermedia I	19	19	45.0	1.3
Y. kristensenii/frederiksenii/intermedia IIc	12	14	89.0	1.3

^an_ref, number of isolates used for reference; n_val, number of isolates used for validation. For internal validation, all spectra which had not been included in the reference data set were used. The probability of obtaining uncertain results during repeated determinations is given by the residual to 100%.

^bFor genus-level determination and for identification of Y. enterocolitica, an external validation was applied using all isolates not included in the reference.

^cAs determined by API 20E.