TABLE 1.

Performance of tests for the identification of S. pneumoniae^a

Test	No. of isolates for which result was:				Sensitivityc	Specificityc	PVPc	PVNc
	True positive	False positive	False negative	True negative
Pneumoslide	98	13	1	88	99.0	87.1	88.3	98.9
Directigen	99	15	0	86	100	85.1	86.8	100
Phadebact	99	2	0	99	100	98.0	98.0	100
Deoxycholate drop	98	2	1	99	99.0	98.0	98.0	99.0
Deoxycholate tube	99	1	0	100	100	99.0	99.0	100
Optochin susceptibility	98	2	1	99	99.0	98.0	98.0	99.0
GPI Cardb	89	4	10	94	89.9	95.9	95.7	90.4
Colony morphology	93	23	6	78	93.9	77.2	80.2	92.9

^aPVP, positive predictive value; PVN, negative predictive value. 

^bThree of the viridans streptococcal isolates were repeatedly determined to have insufficient growth by the GPI Card, and the results for these isolates were not included in the calculation of test specificity. 

^cValues are percentages.