TABLE 1.

MICs of 14 antimicrobials for A. urinae (n = 128), tested by broth microdilution in Mueller-Hinton broth supplemented with 2.5% lysed horse blood and incubated in 5% CO₂, and proposed interpretive criteria, based on CLSI viridans group streptococci and Staphylococcus sp. interpretive criteria

Antibiotic	No. of isolates with MIC (μg/ml) of:											Modal MIC (μg/ml)	% susceptible	Proposed breakpoint (μg/ml) for:
	≤0.015	0.03	0.06	0.12	0.25	0.5	1	2	4	8	>8			Susceptible	Intermediate	Resistant
Penicillin	39	69	15	5								0.03	100	≤0.12	0.25–2	≥4
Amoxicillin	42	32	35	15	3	1						≤0.015		NPa	NP	NP
Cefotaxime	5	12	16	25	39	22	8	1				0.25	99	≤1	2	≥4
Ceftriaxone	4	6	14	24	33	20	22	4	1			0.25	96	≤1	2	≥4
Meropenem	59	33	25	9	0	1	0	1				≤0.015	99	≤0.5	NSb	NS
Erythromycin				39c	45	12	2	2		1	27	0.25		NP	NP	NP
Clindamycin				32c	26	16	19	35d				≥2		NP	NP	NP
Tetracycline				103c	14	5			2		4	≤0.12	95	≤2	4	≥8
Doxycycline					35c	2			1		1	≤0.25		NP	NP	NP
Levofloxacin						70c	32	5	9	9	3	0.5	84	≤2	4	≥8
SXT					63c	28	30	3	3	1d		≤0.25		NP	NP	NP
Rifampin					128c							≤0.25	100	≤1	NS	NS
Linezolid						32c	58	3	1	1d		1	98	≤2	NS	NS
Vancomycin				5c	38	80	5					0.5	100	≤1	NS	NS

^aNP, no proposed breakpoint.

^bNS, due to the rare occurrence of isolates with MICs outside the susceptible range, no intermediate or resistant categories are suggested.

^cMIC less than or equal to the value in the column header.

^dMIC greater than or equal to the value in the column header.