Clinical Usefulness of the 2010 Clinical and Laboratory Standards Institute Revised Breakpoints for Cephalosporin Use in the Treatment of Bacteremia Caused by Escherichia coli or Klebsiella spp.

Table 1

Minimum inhibitory concentration and disk diffusion interpretive breakpoints for several cephalosporins established in January 2009 and January 2010 by the Clinical and Laboratory Standards Institute.

Agent

MIC breakpoints (μg/mL)

Disk diffusion breakpoints (mm)

CLSI 2009 (M100-S19)

CLSI 2010 (M100-S20)

CLSI 2009 (M100-S19)

CLSI 2010 (M100-S20)

S

I

R

S

I

R

S

I

R

S

I

R

Cefazolin

≤8

16

≥32

≤1

2

≥4

≥18

15–17

≤14

NA

NA

NA

Cefotaxime

≤8

16–32

≥64

≤1

2

≥4

≥23

15–22

≤14

≥26

23–25

≤22

Ceftizoxime

≤8

16–32

≥64

≤1

2

≥4

≥20

15–19

≤14

≥25

22–24

≤21

Ceftriaxone

≤8

16–32

≥64

≤1

2

≥4

≥21

14–20

≤13

≥23

20–22

≤19

Ceftazidime

≤8

16

≥32

≤4

8

≥16

≥18

15–17

≤14

≥21

18–20

≤17

MIC, minimum inhibitory concentration; CLSI, Clinical and Laboratory Standards Institute; NA, not available.