ACCEPTABLE ZONE DIAMETER (mm) QUALITY CONTROL LIMITS OF ANTIMICROBIAL DISK SUSCEPTIBILITY TESTS FOR NONFASTIDIOUS ORGANISMS (using Mueller-Hinton Agar Without Blood or Other Supplements)

For Use With CLSI Document M02 - Disk Diffusion

Antimicrobial
Agent
Disk
Content
Escherichia
coli
Staphylococcus
aureus
Pseudomonas
aeruginosa
Escherichia
coli
ATCC ®a 25922 ATCC ®a
25923
ATCC ®a
27853
ATCC ®a 35218 b
Amikacin 30ug 19-26 20-26 18-26 -----
Amoxicillin/Clavulanic Acid 20/10ug 18-24 28-36 ----- 17-22
Ampicillin 10ug 16-22 27-35 ----- 6
Ampicillin/Sulbactam 10/10ug 19-24 29-37 ----- 13-19
Azithromycin 15ug ----- 21-26 ----- -----
Azlocillin 75ug ----- ----- 24-30 -----
Aztreonam 30ug 28-36 ----- 23-29 -----
Carbenicillin 100ug 23-29 ----- 18-24 -----
Cefaclor 30ug 23-27 27-31 ----- -----
Cefamandole 30ug 26-32 26-34 ----- -----
Cefazolin 30ug 21-27 29-35 ----- -----
Cefdinir 5ug 24-28 25-32 ----- -----
Cefditoren 5ug 22-28 20-28 ----- -----
Cefepime 30ug 31-37 23-29 24-30 -----
Cefetamet 10ug 24-29 ----- ----- -----
Cefixime 5ug 23-27 ----- ----- -----
Cefmetazole 30ug 26-32 25-34 ----- -----
Cefonicid 30ug 25-29 22-28 ----- -----
Cefoperazone 75ug 28-34 24-33 23-29 -----
Cefotaxime 30ug 29-35 25-31 18-22 -----
Cefotetan 30ug 28-34 17-23 ----- -----
Cefoxitin 30ug 23-29 23-29 ----- -----
Cefpodoxime 10ug 23-28 19-25 ----- -----
Cefprozil 30ug 21-27 27-33 ----- -----
Ceftaroline 30ug 26-34 26-35 ----- -----
Ceftazidime 30ug 25-32 16-20 22-29 -----
Ceftibuten 30ug 27-35 ----- ----- -----
Ceftizoxime 30ug 30-36 27-35 12-17 -----
Ceftobiprole 30ug 30-36 26-34 24-30 -----
Ceftriaxone 30ug 29-35 22-28 17-23 -----
Cefuroxime 30ug 20-26 27-35 ----- -----
Cephalothin 30ug 15-21 29-37 ----- -----
Chloramphenicol 30ug 21-27 19-26 ----- -----
Cinoxacin 100ug 26-32 ----- ----- -----
Ciprofloxacin 5ug 30-40 22-30 25-33 -----
Clarithromycin 15ug ----- 26-32 ----- -----
Clinafloxacin 5ug 31-40 28-37 27-35 -----
Clindamycin c 2ug ----- 24-30 ----- -----
Colistin 10ug 11-17 ----- 11-17 -----
Daptomycin d 30ug ----- 18-23 ----- -----
Dirithromycin 15ug ----- 18-26 ----- -----
Doripenem 10ug 27 -35 33-42 28 -35 -----
Doxycycline 30ug 18-24 23-29 ----- -----
Enoxacin 10ug 28-36 22-28 22-28 -----
Ertapenem 10ug 29-36 24-31 13-21 -----
Erythromycin c 15ug ----- 22-30 ----- -----
Faropenem 5ug 20-26 27-34 ----- -----
Fleroxacin 5ug 28-34 21-27 12-20 -----
Fosfomycin e 200ug 22-30 25-33 ------ ------
Garenoxacin 5ug 28-35 30-36 19-25 ------
Gatifloxacin 5ug 30-37 27-33 20-28 -----
Gemifloxacin 5ug 29-36 27-33 19-25 -----
Gentamicin f 10ug 19-26 19-27 16-21 -----
Grepafloxacin 5ug 28-36 26-31 20-27 -----
Iclaprim 5ug 14-22 25-33 ----- -----
Imipenem 10ug 26-32 ----- 20-28 -----
Kanamycin 30ug 17-25 19-26 ----- -----
Levofloxacin 5ug 29-37 25-30 19-26 -----
Linezolid 30ug ----- 25-32 ----- -----
Linopristin/Flopristin 10ug ----- 25-31 ----- -----
Lomefloxacin 10ug 27-33 23-29 22-28 -----
Loracarbef 30ug 23-29 23-31 ----- -----
Mecillinam 10ug 24-30 ----- ----- -----
Meropenem 10ug 28-34 29-37 27-33 -----
Methicillin 5ug ----- 17-22 ----- -----
Mezlocillin 75ug 23-29 ----- 19-25 -----
Minocycline 30ug 19-25 25-30 ----- -----
Moxalactam 30ug 28-35 18-24 17-25 -----
Moxifloxacin 5ug 28-35 28-35 17-25 -----
Nafcillin 1ug ----- 16-22 ----- -----
Nalidixic Acid 30ug 22-28 ----- ----- -----
Netilmicin 30ug 22-30 22-31 17-23 -----
Nitrofurantoin 300ug 20-25 18-22 ----- -----
Norfloxacin 10ug 28-35 17-28 22-29 -----
Ofloxacin 5ug 29-33 24-28 17-21 -----
Oxacillin 1ug ----- 18-24 ----- -----
Penicillin 10units ----- 26-37 ----- -----
Piperacillin 100ug 24-30 ----- 25-33 12-18
Piperacillin/Tazobactam 100/10ug 24-30 27-36 25-33 24-30
Polymyxin B 300units 13-19 ----- 14-18 -----
Quinupristin/Dalfopristin 15ug ----- 21-28 ----- -----
Razupenem 10ug 21-26 ----- ----- -----
Rifampin 5ug 8-10 26-34 ----- -----
Sparfloxacin 5ug 30-38 27-33 21-29 -----
Streptomycin f 10ug 12-20 14-22 ----- -----
Sulfisoxazole g 250ug or 300ug 15-23 24-34 ----- -----
Teicoplanin 30ug ----- 15-21 ----- -----
Telavancin 30ug ----- 16-20 ----- -----
Telithromycin 15ug ----- 24-30 ----- -----
Tetracycline 30ug 18-25 24-30 ----- -----
Ticarcillin 75ug 24-30 ----- 21-27 6
Ticarcillin/Clavulanic Acid 75/10ug 24-30 29-37 20-28 21-25
Tigecycline 15ug 20-27 20-25 9-13 -----
Tobramycin 10ug 18-26 19-29 19-25 -----
Trimethoprim g 5ug 21-28 19-26 ----- -----
Trimethoprim/Sulfamethoxazole g 1.25/23.75ug 23-29 24-32 ----- -----
Trospectomycin 30ug 10-16 15-20 ----- -----
Trovafloxacin 10ug 29-36 29-35 21-27 -----
Ulifloxacin (prulifloxacin) 5ug 32-38 20-26 27-33 -----
Vancomycin 30ug ----- 17-21 ----- -----

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. Careful organism maintenance is required; refer to CLSI M02.

c. When disk approximation tests are performed with erythromycin and clindamycin, S. aureus ATCC ®a BAA-977 (containing inducible ermA -mediated resistance) and S. aureus ATCC ®a BAA-976 (containing mrs A-mediated macrolide-only efflux) are recommended as supplemental quality control strains (e.g., training, competency assesment, or test evaluation). S. aureus ATCC ®a BAA-977 should demonstrate inducible clindamycin resistance (i.e., a positive D-zone test), while S. aureus ATCC ®a BAA-976 shoud not demonstrate inducible clindamycin resistance. S. aureus ATCC ®a 25923 should be used for routine quality control (e.g., weekly or daily) of erythromycin and clindamycin disks using standard Mueller Hinton agar.

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

e. The 200ug fosfomycin disk contains 50ug of glucose-6-phosphate.

f. For control limits of gentamicin 120ug and streptomycin 300ug disks, use Enterococcus faecalis ATCC ®a 29212 (gentamicin 16-23mm; streptomycin 14-20mm).

g. These agents can be affected by excess levels of thymidine and thymine. See CLSI M02 for guidance should a problem with quality control occur.

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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