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United States Department of Agriculture

Agricultural Research Service

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2007 Veterinary Isolates Final Report- Accessible Version
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Table 1. Breakpoints (?g/ml) Used for Susceptibility Testing of Salmonella and E.coli
CLSI SubclassAntimicrobialSusceptible breakpointIntermediate breakpointResistant breakpoint
AminoglycosidesAmikacin

<=16

32

>=64

Gentamicin

<=4

8

>=16

Kanamycin

<=16

32

>=64

Streptomycin

<=32

N/A

>=64

AminopenicillinsAmpicillin

<=8

16

>=32

Beta-Lactam/Beta-Lactamase Inhibitor CombinationsAmoxicillin/Clavulanic Acid

<=8/4

16/8

>=32/16

Cephalosporins ICephalothin

<=8

16

>=32

Cephalosporins IIICeftiofur

<=2

4

>=8

Ceftriaxone

<=8

16 and 32

>=64

CephamycinsCefoxitin

<=8

16

>=32

Folate Pathway InhibitorsSulfanomides

<=256

N/A

>=512

Trimethoprim/Sulfamethoxazole

<=2/38

N/A

>=4/76

PhenicolsChloramphenicol

<=8

16

>=32

FluoroquinolonesCiprofloxacin

<=1

2

>=4

QuinolonesNalidixic Acid

<=16

N/A

>=32

TetracyclinesTetracycline

<=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 (?g/ml) Used for Susceptibility Testing of Campylobacter
CLSI SubclassAntimicrobialBroth Microdilution Breakpoints (2005-2007) Etest Breakpoints (1998-2004)
Susceptible Intermediate ResistantSusceptible Intermediate Resistant
AminoglycosidesGentamicin

<=2

4

>=8

<=4

8

>=16

LincosamidesClindamycin

<=2

4

>=8

<=0.5

1 and 2

>=4

MacrolidesAzithromycin

<=2

4

>=8

<=0.25

0.5 and 1

>=2

Erythromycin

<=8

16

>=32

<=0.5

1 and 4

>=8

KetolidesTelithromycin

<=4

8

>=16

NT

NT

NT

PhenicolsFlorfenicol

<=4

N/A

N/A

NT

NT

NT

Chloramphenicol

NT

NT

NT

><=8

16

>=32

FluoroquinolonesCiprofloxacin

<=1

2

>=4

<=1

2

>=4

QuinolonesNalidixic acid

<=16

32

>=64

<=16

N/A

>=32

TetracyclinesTetracycline

<=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

 

 

 

 


Last Modified: 8/13/2016
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