Breakpoints Used for Susceptibility Testing of Salmonella and E. coli¹

		Antimicrobial Concentration Range  (µg/ml)								Breakpoints (µg/ml)
CLSI Class2	Antimicrobial Agent	1997	1998	1999	2000	2001	2002-2003	2004-2010	2011-2012	Susceptible	Intermediate	Resistant
	Amikacin	4  -  32	4  -  32	4  -  32	4  -  32	4  -  32	0.5  -  4	0.5  -  64	NT	< 16	32	> 64
Aminoglycosides	Apramycin	2  -  16	2  -  16	2  -  32	2  -  32	2  -  32	NT	NT	NT	N/A	N/A	>32
	Gentamicin	0.25 -- 16	0.25 -- 16	0.25  -  16	0.25  -  16	0.25  -  16	0.25  -  16	0.25  -  16	0.25  -  16	< 4	8	> 16
	Kanamycin	16  -  64	16  -  64	16  -  64	16  -  64	16  -  64	8  -  64	8  -  64	8  -  64	< 16	32	> 64
	Streptomycin3	32  -  256	32  -  256	32  -  256	32  -  256	32  -  64	32  -  64	32  -  64	32  -  64	< 32	N/A	> 64
β-Lactam/β-Lactamase  Inhibitor Combinations	Amoxicillin–          Clavulanic Acid	0.5/0.25  -  32/16	0.5/0.25  -  32/16	0.5/0.25  -  32/16	0.5/0.25  -  32/16	0.5/0.25  -  32/16	1/0.5  -  32/16	1/0.5  -  32/16	1/0.5  -  32/16	< 8 / 4	16/8	> 32 / 16
Carbapenem	Imipenem	NT	NT	NT	NT	0.25  -  8	NT	NT	NT	< 4	8	>16
Carboxypenicillins	Ticarcillin	2  -  128	2  -  128	NT	NT	NT	NT	NT	NT	< 16	32 - 64	>128
Cephems	Cephalothin	1 - 32	1 - 32	1 - 32	1 - 32	1 - 32	2 - 32	NT	NT	< 8	16	> 32
	Ceftiofur	0.5  -  16	0.5  -  16	0.5  -  16	0.5  -  16	0.5  -  16	0.12  -  8	0.12  -  8	0.12  -  8	< 2	4	> 8
	Cefoxitin	NT	NT	NT	4  -  32	4  -  32	0.5  -  16	0.5  -  32	0.5  -  32	≤ 8	16	> 32
	Ceftriaxone	0.25  -  16	0.25  -  16	0.25  -  64	0.25  -  64	0.25  -  64	0.25  -  64	0.25  -  64	0.25  -  64	≤ 1	2	≥ 4
Folate Pathway Inhibitors	Sulfonamides   Sulfamethoxazole: 1998-2003/Sulfizoxazole: 2004-2009	128  -  512	128  -  512	128  -  512	128  -  512	128  -  512	16  -  512	16  -  256	16  -  256	≤ 256	N/A	> 512
	Trimethoprim– Sulfamethoxazole	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	0.12/2.4 - 4/76	≤ 2 / 38	N/A	> 4 / 76
Macrolide	Azithromycin3	NT	NT	NT	NT	NT	NT	NT	0.12  -  16	N/A	N/A	N/A
Penicillins	Ampicillin	2  -  64	2  -  64	2  -  32	2  -  32	2  -  32	1  -  32	1  -  32	1  -  32	< 8	16	> 32
Phenicols	Chloramphenicol	4  -  32	4  -  32	4  -  32	4  -  32	4  -  32	2  -  32	2  -  32	2  -  32	≤  8	16	> 32
	Florfenicol	NT	NT	2  -  16	NT	NT	NT	NT	NT	N/A	N/A	N/A
Quinolones	Ciprofloxacin	0.015  -  2	0.015  -  2	0.015  -  4	0.015  -  4	0.015  -  4	0.015  -  4	0.015  -  4	0.015  -  4	≤ 0.06	0.12 -0.5	> 1
	Nalidixic acid	4  -  64	4  -  64	4  -  256	4  -  256	4  -  64	0.5  -  32	0.5  -  32	0.5  -  32	≤ 16	N/A	> 32
Tetracyclines	Tetracycline	4  -  64	4  -  64	4  -  32	4  -  32	8  - 16	4  -  32	4  -  32	4  -  32	≤ 4	8	> 16

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¹Breakpoints established by CLSI (Clinical and Laboratory Standards Institute) were used when available
²According to CLSI M100 document
³There are no CLSI breakpoints for streptomycin

NT=Not tested
NA=Not applicable

Breakpoints Used for Susceptibility Testing of Campylobacter¹

	Antimicrobial Agent	Antimicrobial Concentration Range  (µg/ml) 1998-2004	Breakpoints (µg/ml) Etest (1998-2004)			Antimicrobial Concentration Range  (µg/ml) 2005-2012	Breakpoints (µg/ml) Microbroth Dilution (2005-2012)
			Susceptible	Intermediate	Resistant		Susceptible	Intermediate	Resistant
CLSI Subclass2
Aminoglycosides	Gentamicin	0.016 - 256	< 4	8	> 16	0.12 - 32	< 2	4	> 8
Lincosamides	Clindamycin	0.016 - 256	< 0.5	1 - 2	> 4	0.03 - 16	< 2	4	> 8
Macrolides	Azithromycin	0.016 - 256	< 0.25	0.5 - 1	> 2	0.015 - 64	< 2	4	> 8
	Erythromycin	0.016 - 256	< 0.5	1 - 4	> 8	0.03 - 64	< 8	16	> 32
Ketolides	Telithromycin	NT	NT	NT	NT	0.015 - 8	< 4	8	> 16
Phenicols	Florfenicol	NT	NT	NT	NT	0.03 - 64	< 4	N/A	N/A
	Chloramphenicol	0.016 - 256	< 8	16	> 32	NT	NT	NT	NT
Fluoroquinolones	Ciprofloxacin	0.002 - 32	< 1	2	> 4	0.015 - 64	< 1	2	> 4
Quinolones	Nalidixic acid	0.016 - 256	< 16	N/A	> 32	4 - 64	< 16	32	> 64
Tetracyclines	Tetracycline	0.016 - 256	< 4	8	> 16	0.06 - 64	< 4	8	> 16

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¹Breakpoints established by CLSI (Clinical and Laboratory Standards Institute)were used when available. CLSI breakpoints are only available
for erythromycin, ciprofloxacin, and tetracycline
²According to CLSI M100 document

NT=Not tested
NA=Not applicable

Breakpoints Used for Susceptibility Testing of Enterococcus¹

CLSI Subclass2	Antimicrobial Agent	Antimicrobial Concentration Range  (µg/ml)				Breakpoints  (µg/ml)
		2003	2004-2005	2006-2008	2009-2012	Susceptible	Intermediate	Resistant
Aminoglycoside	Gentamicin	128 - 1024	128 - 1024	128 - 1024	128 - 1024	≤ 500	N/A	> 500
	Kanamycin	128 - 1024	128 - 1024	128 - 1024	128 - 1024	≤ 512	N/A	> 1024
	Streptomycin	512 - 2048	512 - 2048	512 - 2048	512 - 2048	≤ 1000	N/A	> 1000
Glycopeptide	Vancomycin	0.5-32	0.5 - 32	0.5 - 32	0.25 - 32	≤ 4	8 - 16	> 32
Glycylcycline	Tigecycline	NT	NT	0.015 - 0.5	0.015 - 0.5	≤ 0.25	N/A	N/A4
Ionophore coccidiostat	Salinomycin	1 - 32	NT	NT	NT	≤8	-	≥16
Lincosamides	Lincomycin	1 - 32	1 - 32	1 - 32	1 - 8	≤ 2	4	≥ 8
Lipopeptide	Daptomycin	NT	0.5 - 16	0.5 - 16	0.25 - 16	≤ 4	N/A	N/A5
Macrolide	Erythromycin	0.5 - 8	0.5 - 8	0.5 - 8	0.25 - 8	≤ 0.5	1 - 4	≥ 8
	Tylosin	0.25 - 32	0.25 - 32	0.25 - 32	0.25 - 32	≤ 8	16	≥32
Nitrofuran	Nitrofurantoin	2 - 128	2 - 128	2 - 64	2 - 64	≤ 32	64	≥128
Oxazolidinones	Linezolid	0.5 - 8	0.5 - 8	0.5  -  8	0.5 - 8	≤ 2	4	≥ 8
Penicillin	Penicillin	0.5 - 16	0.5 - 16	0.5 - 16	0.25 - 16	≤ 8	N/A	≥ 16
Phenicol	Chloramphenicol	2 - 32	2 - 32	2 - 32	2 - 32	≤ 8	16	≥ 32
Phosphoglycolipid	Flavomycin	1 - 32	1 - 32	1 - 16	NT	≤ 8	16	≥ 32
Polypeptide	Bacitracin	8 - 128	8 - 128	NT	NT	≤ 16	32	≥ 64
Quinolone	Ciprofloxacin	0.12 - 4	0.12 - 4	0.12 - 4	0.12 - 4	≤ 1	2	≥ 4
Streptogramin	Quinupristin/Dalfoprisitin	1 - 32	1 - 32	1 - 32	0.5 - 32	≤ 1	2	≥ 4
Tetracycline	Tetracycline	4 - 32	4 - 32	4 - 32	1 - 32	≤ 4	8	≥ 16

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¹Breakpoints established by CLSI (Clinical and Laboratory Standards Institute)were used when available
²According to CLSI M100 document
³For the aminoglycosides, breakpoints refer to high-level aminoglycoside resistance
⁴For tigecycline, only a susceptible breakpoint (≤ 0.25 µg/ml) has been established
⁵For daptomycin, only a susceptible breakpoint (≤ 4 µg/ml) has been established

NT=Not tested
NA=Not applicable