TABLE 6.

ESBL results for the E. coli and Klebsiella isolates tested in this study

Isolate type and species	No. of resultsa:					Result (%) forb:
	Total	+ by both tests	PHX+ and REF−	PHX− and REF+	− by both tests	Sensitivity	Specificity	PPV	NPV	Agreement
Clinical
E. coli	71	6	0	0	65	100	100	100	100	100
K. pneumoniae	49	7	0	0	42	100	100	100	100	100
K. oxytoca	27	5	1	0	21	100	95.5	83.3	100	96.3
Challenge
E. coli	31	12	1	1	17	92.3	94.4	92.3	94.4	93.5
K. pneumoniae	20	17	0	0	3	100	100	100	100	100
K. oxytoca	5	3	0	0	2	100	100	100	100	100
Clinical and challenge
E. coli	102	18	1	1	82	94.7	98.8	94.7	98.8	98.0
K. pneumoniae	69	24	0	0	45	100	100	100	100	100
K. oxytoca	32	8	1	0	23	100	95.8	88.9	100	96.9
Total	203	50	2	1	150	98.0	98.7	96.2	99.3	98.5

^aPHX, Phoenix system; REF, reference method. +, positive; −, negative.

^bPPV, positive predictive value; NPV, negative predictive value.