European Committee on Antimicrobial Susceptibility Testing

Streptococcus groups A, B, C and G EUCAST Clinical Breakpoint Tables v. 7.0, valid from 2017-01-01
Macrolides, lincosamides and streptogramins
MIC breakpoint
(mg/L)
Disk
content
Zone diameter
breakpoint
(µg) (mm)
S ≤ R > S ≥ R <
Azithromycin 0.25 1 0.5 1 Note A Note A
Notes
Numbered notes relate to general comments and/or MIC breakpoints.
Lettered notes relate to the disk diffusion method.
Clarithromycin
Erythromycin
Roxithromycin
Telithromycin
Clindamycin
Quinupristin-dalfopristin
Tetracyclines
Doxycycline
Minocycline
Tetracycline
Tigecycline
Oxazolidinones
Linezolid 1
Tedizolid 1 0.25 1
0.25 1
0.5 1
0.25
0.5
-
MIC breakpoint
(mg/L)
S ≤
1 1
0.5 1
1 1
0.25 3
MIC breakpoint
(mg/L)
S ≤
2
0.5 2 0.5 1
0.5 1
1 1
0.5
0.5
-
R >
2 1
1 1
2 1
0.5 3
R >
4
0.5
Note A
21 A
Note A
20
17 B -
Zone
breakpoint
(mm)
S ≥
Note A
23 A
23 A
19
Zone
breakpoint
(mm)
S ≥
19
Note A Note A
18 A
Note A
17
17 B
-
diameter
R <
Note A
20 A
20 A
16
diameter
R <
16
Note A 1/A. Erythromycin can be used to determine susceptibility to azithromycin, clarithromycin and roxithromycin.
2. Inducible clindamycin resistance can be detected by antagonism of clindamycin activity by a macrolide agent.
then report as susceptible. If detected, then report as resistant and consider adding this comment to the report:
still be used for short-term therapy of less serious skin and soft tissue infections as constitutive resistance is
during such therapy". The clinical importance of inducible clindamycin resistance in combination treatment of
infections is not known.
B. Place the erythromycin and clindamycin disks 12-16 mm apart (edge to edge) and look for antagonism (the
detect inducible clindamycin resistance.
Notes
Numbered notes relate to general comments and/or MIC breakpoints.
Lettered notes relate to the disk diffusion method.
1/A. Isolates susceptible to tetracycline are also susceptible to doxycycline and minocycline, but some resistant
be susceptible to minocycline and/or doxycycline. An MIC method should be used to test doxycycline susceptibility
resistant isolates if required.
2. Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test
isolate must be confirmed and the isolate sent to a reference laboratory.
3. For tigecycline broth microdilution MIC determination, the medium must be prepared fresh on the day of use.
Notes
Numbered notes relate to general comments and/or MIC breakpoints.
Lettered notes relate to the disk diffusion method.
1. Non-susceptible isolates are rare or not yet reported. The identification and antimicrobial susceptibility test
isolate must be confirmed and the isolate sent to a reference laboratory.
2. Isolates susceptible to linezolid can be reported susceptible to tedizolid.
If not detected,
"Clindamycin may
15
unlikely to develop
severe S. pyogenes
15 2 2 D phenomenon) to
Disk
content
(µg)
to tetracycline may
30 of tetracycline
30
result on any such
2 15
Disk
content
(µg)
10 result on any such
A. Isolates susceptible to linezolid can be reported susceptible to tedizolid. For isolates resistant to linezolid, perform an MIC test.
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