Table 1. Breakpoints (µg/ml) Used for Susceptibility Testing of Salmonella and E.coli

CLSI Subclass	Antimicrobial	Susceptible breakpoint	Intermediate breakpoint	Resistant breakpoint
Aminoglycosides	Amikacin	<=16	32	>=64
	Gentamicin	<=4	8	>=16
	Kanamycin	<=16	32	>=64
	Streptomycin	<=32	N/A	>=64
Aminopenicillins	Ampicillin	<=8	16	>=32
Beta-Lactam/Beta-Lactamase Inhibitor Combinations	Amoxicillin/Clavulanic Acid	<=8/4	16/8	>=32/16
Cephalosporins I	Cephalothin	<=8	16	>=32
Cephalosporins III	Ceftiofur	<=2	4	>=8
	Ceftriaxone	<=8	16 and 32	>=64
Cephamycins	Cefoxitin	<=8	16	>=32
Folate Pathway Inhibitors	Sulfanomides	<=256	N/A	>=512
	Trimethoprim/Sulfamethoxazole	<=2/38	N/A	>=4/76
Phenicols	Chloramphenicol	<=8	16	>=32
Fluoroquinolones	Ciprofloxacin	<=1	2	>=4
Quinolones	Nalidixic Acid	<=16	N/A	>=32
Tetracyclines	Tetracycline	<=4	8	>=16

Table 1 notes:

Breakpoints established by CLSI (Clinical and Laboratory Standards Institute) were used when available

CLSI subclasses are in accordance with CLSI M100 document.

No CLSI breakpoints are available for streptomycin

N/A - Not applicable

 

Table 2. Breakpoints (µg/ml) Used for Susceptibility Testing of Campylobacter

CLSI Subclass	Antimicrobial	Broth Microdilution Breakpoints (2005-2007)			Etest Breakpoints (1998-2004)
		Susceptible	Intermediate	Resistant	Susceptible	Intermediate	Resistant
Aminoglycosides	Gentamicin	<=2	4	>=8	<=4	8	>=16
Lincosamides	Clindamycin	<=2	4	>=8	<=0.5	1 and 2	>=4
Macrolides	Azithromycin	<=2	4	>=8	<=0.25	0.5 and 1	>=2
	Erythromycin	<=8	16	>=32	<=0.5	1 and 4	>=8
Ketolides	Telithromycin	<=4	8	>=16	NT	NT	NT
Phenicols	Florfenicol	<=4	N/A	N/A	NT	NT	NT
	Chloramphenicol	NT	NT	NT	><=8	16	>=32
Fluoroquinolones	Ciprofloxacin	<=1	2	>=4	<=1	2	>=4
Quinolones	Nalidixic acid	<=16	32	>=64	<=16	N/A	>=32
Tetracyclines	Tetracycline	<=4	8	>=16	<=4	8	>=16

 

Table 2 notes:

Breakpoints established by CLSI (Clinical and Laboratory Standards Institute) were used when available. CLSI breakpoints are available only for erythromycin, ciprofloxacin, and tetracycline

CLSI subclasses are in accordance with CLSI M100 document.

N/A - Not applicable

NT - Not tested

 

 

Return to the NARMS 2007 Veterinary Isolates Final Report Table of Contents