Acceptable QC Limits of Zone Diameters for Fastidious Organisms

For Use With CLSI Document M02 - Disk Diffusion

Antimicrobial Agent Disk Content Haemophilus influenzae
ATCC ®a 49247
Haemophilus influenzae

ATCC ®a 49766
Neisseria gonorrhoeae

ATCC ®a 49226
Streptococcus pneumoniae

ATCC ®a 49619 b
Amoxicillin/
Clavulanic Acid c
20/10ug
15-23
-----
-----
------
Ampicillin
10ug
13-21
-----
------
30-36
Ampicillin/
Sulbactam
10/10ug
14-22
-----
-----
-----
Azithromycin
15ug
13-21
-----
-----
19-25
Aztreonam
30ug
30-38
-----
-----
-----
Cefaclor
30ug
-----
25-31
-----
24-32
Cefdinir
5ug
-----
24-31
40-49
26-31
Cefditoren
5ug
25-34
-----
-----
27-35
Cefepime
30ug
25-31
-----
37-46
28-35
Cefetamet
10ug
23-28
-----
35-43
-----
Cefixime
5ug
25-33
-----
37-45
16-23
Cefmetazole
30ug
16-21
-----
31-36
-----
Cefonicid
30ug
-----
30-38
-----
-----
Cefotaxime
30ug
31-39
-----
38-48
31-39
Cefotetan
30ug
-----
-----
30-36
-----
Cefoxitin
30ug
-----
-----
33-41
-----
Cefpodoxime
10ug
25-31
-----
35-43
28-34
Cefprozil
30ug
-----
20-27
-----
25-32
Ceftaroline
30ug
29-39
-----
-----
31-41
Ceftazidime
30ug
27-35
-----
35-43
-----
Ceftibuten
30ug
29-36
-----
-----
-----
Ceftizoxime
30ug
29-39
-----
42-51
28-34
Ceftobiprole d
30ug
28-36
30-38
-----
33-39
Ceftriaxone
30ug
31-39
-----
39-51
30-35
Cefuroxime
30ug
-----
28-36
33-41
-----
Cephalothin
30ug
-----
-----
-----
26-32
Chloramphenicol
30ug
31-40
-----
-----
23-27
Ciprofloxacin
5ug
34-42
-----
48-58
-----
Clarithromycin
15ug
11-17
-----
-----
25-31
Clinafloxacin
5ug
34-43
-----
-----
27-34
Clindamycin
2ug
-----
-----
-----
19-25
Daptomycin e
30ug
-----
-----
-----
19-26
Dirithromycin
15ug
-----
-----
-----
18-25
Doripenem
10ug
21-31
-----
-----
30-38
Enoxacin
10ug
-----
-----
43-51
-----
Ertapenem
10ug
20-28
27-33
-----
28-35
Erythromycin
15ug
-----
-----
-----
25-30
Faropenem
5ug
15-22
-----
-----
27-35
Fleroxacin
5ug
30-38
-----
43-51
-----
Garenoxacin
5ug
33-41
-----
-----
26-33
Gatifloxacin
5ug
33-41
-----
45-56
24-31
Gemifloxacin
5ug
30-37
-----
-----
28-34
Grepafloxacin
5ug
32-39
-----
44-52
21-28
Iclaprim
5ug
24-33
-----
-----
21-29
Imipenem
10ug
21-29
-----
-----
-----
Levofloxacin
5ug
32-40
-----
-----
20-25
Linezolid
30ug
-----
-----
-----
25-34
Linopristin/Flopristin
10ug
25-31
-----
-----
22-28
Lomefloxacin
10ug
33-41
-----
45-54
-----
Loracarbef
30ug
-----
26-32
-----
22-28
Meropenem
10ug
20-28
-----
-----
28-35
Moxifloxacin
5ug
31-39
-----
-----
25-31
Nitrofurantoin
300ug
-----
-----
-----
23-29
Norfloxacin
10ug
-----
-----
-----
15-21
Ofloxacin
5ug
31-40
-----
43-51
16-21
Oxacillin
1ug
-----
-----
-----
< 12 f
Penicillin
10units
-----
-----
26-34
24-30
Piperacillin/
Tazobactam
100/10ug
33-38
-----
-----
-----
Quinupristin/
Dalfopristin
15ug
15-21
-----
-----
19-24
Razupenem
10ug
24-30
-----
-----
29-36
Rifampin
5ug
22-30
-----
-----
25-30
Sparfloxacin
5ug
32-40
-----
43-51
21-27
Spectinomycin
100ug
-----
-----
23-29
-----
Telavancin
30ug
-----
-----
-----
17-24
Telithromycin
15ug
17-23
-----
-----
27-33
Tetracycline
30ug
14-22
-----
30-42
27-31
Tigecycline
15ug
23-31
-----
30-40
23-29
Trimethoprim/
Sulfamethoxazole
1.25/23.75ug
24-32
-----
-----
20-28
Trospectomycin
30ug
22-29
-----
28-35
-----
Trovafloxacin
10ug
32-39
-----
42-55
25-32
Vancomycin
30ug
-----
-----
-----
20-27

Disk Diffusion Testing Conditions for
Clinical Isolates and Performance of QC

Organism Haemophilus
influenzae
Neisseria
gonorrhoeae
Streptococci and
Neisseria meningitidis
Medium
Haemophilus Test Medium (HTM)
GC Agar Base and 1% defined growth supplement. The use of a cysteine-free growth supplement is not required for disk diffusion testing. Mueller Hinton Agar Supplemented with 5% defibrinated Sheep Blood
Inoculum Direct Colony Suspension Direct Colony Suspension Direct Colony Suspension
Incubation Characteristics 5% CO 2 ; 16-18 hours;
35 degrees C.
5% CO 2 ; 20-24 hours;
35 degrees C.
5% CO 2 ; 20-24 hours;
35 degrees C.

Note: Information in boldface type is considered tentative for one year.

Footnotes

a. ATCC is a registered trademark of the American Type Culture Collection.

b. Despite the lack of reliable disk diffusion interpretive criteria for S. pneumoniae with certain beta-lactams, Streptococcus pneumoniae ATCC ®a 49619 is the strain designated for quality control of all disk diffustion tests with all Streptococcus spp.

c. When testing Haemophilus on HTM, the acceptable limits for QC strain E. coli ATCC ®a 35218 are 17-22mm for amoxicillin/clavulanic acid when incubated in ambient air.

d. Either H. influenzae ATCC ®a 49247 or 49766 may be used for routine quality control testing.

e. Some lots of Mueller Hinton Agar are deficient in calcium and give small zones.

f. Deterioration in oxacillin disk content is best assessed with QC organism Staphylococcus aureus ATCC ®a 25293, with an acceptable zone diameter of 18-24mm.

For more information, please consult the most current CLSI document.

REFERENCES

Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS) . Performance Standards for Antimicrobial Susceptibility Testing. Informational Supplement . M100. CLSI, Wayne, PA.

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