Table 3.

Proposed resistance and susceptibility zone diameter breakpoints using the CLSI and EUCAST MIC breakpoints for urinary isolates of E. coli and Enterococcus faecalis

Standard and species	Option	Diam (mm) for the following interpretive criteriad:			Error rate (%)
		S≥	I	R≤	Major	Very major	Minor	Total
CLSI
Enterobacteriaceaea	Current	16	13–15	12	4	0	9	13.7
	Alternative	13	10–12	9	2	0	5	8
E. coli	Current	16	13–15	12	0	0	0	0
	Alternative	13	10–12	9	0	0	0	0
K. pneumoniae	Current	16	13–15	12	4	0	2	6
	Alternative	13	10–12	9	3	0	2	5
E. cloacae	Current	16	13–15	12	11	0	22	33
	Alternative	13	10–12	9	6	0	16	19
Enterococcus spp.	Current	16	13–15	12	0	0	4.4	4.4
S. aureus	Current	16	13–15	12	0	0	0	0
	Alternative	19	13–18	12	0	0	0	0
P. aeruginosa	Current	16	13–15	12	10	0	41	51
	Alternative	13	10–12	9	2	0	17	19
EUCAST
Enterobacteriaceaea	2 breakpoints	14		14	3.3	3.7		7
	3 breakpoints	14	11–13	11	1	3.7	5	9.7
E. coli	2 breakpoints	14		14	0	0	0	0
	Alternativeb	17		17	0	0	0	0
K. pneumoniae	2 breakpoints	14		14	1	5		6
	3 breakpoints	16	14–15	14	1	3	9	13
E. cloacae	2 breakpoints	14		14	9	6		15
	3 breakpoints	14	12–13	12	3	6	17	26
E. faecalisc	2 breakpoints	14		14	0	4.4		4.4
S. aureus	2 breakpoints	32		32	3	1		4
	3 breakpoints	32	29–31	29	0	1.0	6.0	7.0

^aIncludes E. coli, K. pneumoniae, and E. cloacae only.

^bAlternative with only 2 breakpoints, as no resistant strains were detected.

^cHigh rates of resistance in wild-type E. faecium precluded their inclusion.

^dS≥, diameter greater than or equal to the breakpoint for susceptibility; I, intermediate diameter; ≤R, diameter greater than or equal to the breakpoint for resistance.