1

Zone diameters of antimicrobial agents according to CLSI guidelines 2011

Zone diameters are in mm

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Acinetobacter spp ≥17 15-16 ≤14 Enterobacteriaceae ≥17 15-16 ≤14 Pseudomonas aeruginosa ≥17 15-16 ≤14

Amikacin 30 µg

Staphylococcus aureus ≥17 15-16 ≤14 Enterobacteriaceae ≥18 14-17 ≤13 Haemophilus influenzae ≥20 ≤19

Amoxycillin - Clavulanic acid 20/10 µg

Staphylococcus aureus (MSSA) ≥20 ≤19 Beta-Hemolytic Streptococci ≥24 Enterobacteriaceae ≥17 14-16 ≤13 Enterococcus spp ≥17 ≤16 Haemophilus influenzae ≥22 19-21 ≤18

Ampicillin 10 µg

Staphylococcus aureus ≥29 ≤28 Acinetobacter spp ≥15 12-14 ≤11 Enterobacteriaceae ≥15 12-14 ≤11 Haemophilus influenzae ≥20 ≤19

Ampicillin - Sulbactam 10/10 µg

Staphylococcus aureus (MSSA) ≥15 12-14 ≤11 Beta-Hemolytic Streptococci ≥18 14-17 ≤13 Haemophilus influenzae ≥12 Neisseria meningitidis ≥20 Staphylococcus aureus ≥18 14-17 ≤13 Streptococcus pneumoniae ≥18 14-17 ≤13

Azithromycin 15 µg

Viridans Group Streptococci ≥18 14-17 ≤13

2

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Azlocillin 75 µg Pseudomonas aeruginosa ≥18 ≤17 Enterobacteriaceae ≥21 18-20 ≤17 Haemophilus influenzae ≥26 Aztreonam 30 µg Pseudomonas aeruginosa ≥22 16-21 ≤15 Enterobacteriaceae ≥23 20-22 ≤19 Carbenicillin 100 µg Pseudomonas aeruginosa ≥17 14-16 ≤13

Cedinir 5 µg Enterobacteriaceae ≥20 17-19 ≤16 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥20 17-19 ≤16 Cefaclor 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Enterobacteriaceae ≥18 15-17 ≤14 Cefamandole 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Enterobacteriaceae ≥23 20-22 ≤19 Cefazolin 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Haemophilus influenzae ≥20 Cefdinir 5 µg Staphylococcus aureus (MSSA) ≥20 17-19 ≤16 Acinetobacter spp ≥18 15-17 ≤14 Beta-Hemolytic Streptococci ≥24 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥26 Neisseria gonorrhoeae ≥31 Pseudomonas aeruginosa ≥18 15-17 ≤14 Staphylococcus aureus (MSSA) ≥18 15-17 ≤14

Cefepime 30 µg

Viridans Group Streptococci ≥24 22-23 ≤21 Enterobacteriaceae ≥18 15-17 ≤14 Cefetamet 10 µg Neisseria gonorrhoeae ≥29

3

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Enterobacteriaceae ≥19 16-18 ≤15 Haemophilus influenzae ≥21 Cefixime 5 µg Neisseria gonorrhoeae ≥31 Enterobacteriaceae ≥16 13-15 ≤12 Neisseria gonorrhoeae ≥33 28-32 ≤27 Cefmetazole 30 µg Staphylococcus aureus (MSSA) ≥16 13-15 ≤12 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥20 17-19 ≤16 Cefonicid 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Enterobacteriaceae ≥21 16-20 ≤15 Cefoperazone 75 µg Staphylococcus aureus (MSSA) ≥21 16-20 ≤15 Acinetobacter spp ≥23 15-22 ≤14 Beta-Hemolytic Streptococci ≥24 Enterobacteriaceae ≥26 23-25 ≤22 Haemophilus influenzae ≥26 Neisseria gonorrhoeae ≥31 Neisseria meningitidis ≥34 Staphylococcus aureus (MSSA) ≥23 15-22 ≤14

Cefotaxime 30 µg

Viridans Group Streptococci ≥28 26-27 ≤24 Enterobacteriaceae ≥16 13-15 ≤12 Neisseria gonorrhoeae ≥26 20-25 ≤19 Cefotetan 30 µg Staphylococcus aureus (MSSA) ≥16 13-15 ≤12 Coagulase negative Staphylococci ≥25 ≤24 Enterobacteriaceae ≥18 15-17 ≤14 Neisseria gonorrhoeae ≥28 24-27 ≤23

Cefoxitin 30 µg

Staphylococcus aureus ≥22 ≤21

4

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Enterobacteriaceae ≥21 18-20 ≤17 Haemophilus influenzae ≥21 Neisseria gonorrhoeae ≥29

Cefpodoxime 10 µg

Staphylococcus aureus (MSSA) ≥21 18-20 ≤17 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥18 15-17 ≤14 Cefprozil 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Acinetobacter spp ≥18 15-17 ≤14 Burkholderia cepacia ≥21 18-20 ≤17 Enterobacteriaceae ≥21 18-20 ≤17 Haemophilus influenzae ≥26 Neisseria gonorrhoeae ≥31 Pseudomonas aeruginosa ≥18 15-17 ≤14

Ceftazidime 30 µg

Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Enterobacteriaceae ≥21 18-20 ≤17 Ceftibuten 30 µg Haemophilus influenzae ≥28 Enterobacteriaceae ≥25 22-24 ≤21 Haemophilus influenzae ≥26 Neisseria gonorrhoeae ≥38

Ceftizoxime 30 µg

Staphylococcus aureus (MSSA) ≥20 15-19 ≤13 Acinetobacter spp ≥21 14-20 ≤13 Beta-Hemolytic Streptococci ≥24 Enterobacteriaceae ≥23 20-22 ≤19 Haemophilus influenzae ≥26 Neisseria gonorrhoeae ≥35 Neisseria meningitidis ≥34

Ceftriaxone 30 µg

Staphylococcus aureus (MSSA) ≥21 14-20 ≤13

5

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Ceftriaxone 30 µg Viridans Group Streptococci ≥27 25-26 ≤24 Enterobacteriaceae ≥23 15-22 ≤21 Haemophilus influenzae ≥20 17-19 ≤16 Cefuroxime (oral) 30 µg Staphylococcus aureus (MSSA) ≥23 15-22 ≤14 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥20 17-19 ≤16 Neisseria gonorrhoeae ≥31 26-30 ≤25

Cefuroxime (parenteral) 30 µg

Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Enterobacteriaceae ≥18 15-17 ≤14 Cephalothin 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14 Beta-Hemolytic Streptococci ≥21 18-20 ≤17 Enterobacteriaceae ≥18 13-17 ≤12 Enterococcus spp ≥18 13-17 ≤12 Haemophilus influenzae ≥29 26-28 ≤25 Neisseria meningitidis ≥26 20-25 ≤19 Staphylococcus aureus ≥18 13-17 ≤12 Streptococcus pneumoniae ≥21 ≤20

Chloramphenicol 30 µg

Viridans Group Streptococci ≥21 18-20 ≤17 Acinetobacter spp ≥21 16-20 ≤15 Enterobacteriaceae ≥21 16-20 ≤15 Enterococcus spp ≥21 16-20 ≤15 Haemophilus influenzae ≥21 Neisseria gonorrhoeae ≥41 28-40 ≤27 Neisseria meningitidis ≥35 33-34 ≤32 Pseudomonas aeruginosa ≥21 16-20 ≤15

Ciprofloxacin 5 µg

Staphylococcus aureus ≥21 16-20 ≤15

6

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Beta-Hemolytic Streptococci ≥21 17-20 ≤16 Haemophilus influenzae ≥13 11-12 ≤10 Staphylococcus aureus ≥18 14-17 ≤13 Streptococcus pneumoniae ≥21 17-20 ≤16

Clarithromycin 15 µg

Viridans Group Streptococci ≥21 17-20 ≤16 Beta-Hemolytic Streptococci ≥19 16-18 ≤15 Staphylococcus aureus ≥21 15-20 ≤14 Streptococcus pneumoniae ≥19 16-18 ≤15

Clindamycin 2 µg

Viridans Group Streptococci ≥19 16-18 ≤15 Colistin 10 µg Pseudomonas aeruginosa ≥11 ≤10

Beta-Hemolytic Streptococci ≥18 14-17 ≤13 Staphylococcus aureus ≥19 16-18 ≤15 Streptococcus pneumoniae ≥18 14-17 ≤13

Dirithromycin 15 µg

Viridans Group Streptococci ≥18 14-17 ≤13 Doripenem 10 µg Enterobacteriaceae ≥23 20-22 ≤19

Acinetobacter spp ≥13 10-12 ≤9 Enterobacteriaceae ≥14 11-13 ≤10 Enterococcus spp ≥16 13-15 ≤12

Doxycycline 30 µg

Staphylococcus aureus ≥16 13-15 ≤12 Enterobacteriaceae ≥18 15-17 ≤14 Neisseria gonorrhoeae ≥36 32-35 ≤31 Enoxacin 10 µg Staphylococcus aureus ≥18 15-17 ≤14 Enterobacteriaceae ≥23 20-22 ≤19 Haemophilus influenzae ≥19 Ertapenem 10 µg Staphylococcus aureus (MSSA) ≥19 16-18 ≤15

7

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Beta-Hemolytic Streptococci ≥21 16-20 ≤15 Enterococcus spp ≥23 14-22 ≤13 Staphylococcus aureus ≥23 14-22 ≤13 Streptococcus pneumoniae ≥21 16-20 ≤15

Erythromycin 15 µg

Viridans Group Streptococci ≥21 16-20 ≤15 Haemophilus influenzae ≥19 Neisseria gonorrhoeae ≥35 29-34 ≤28 Fleroxacin 5 µg Staphylococcus aureus ≥19 16-18 ≤15 Enterobacteriaceae ≥16 13-15 ≤12 Fosfomycin 200 µg Enterococcus spp ≥16 13-15 ≤12 Acinetobacter spp ≥18 15-17 ≤14 Beta-Hemolytic Streptococci ≥21 18-10 ≤17 Enterobacteriaceae ≥18 15-17 ≤14 Enterococcus spp ≥18 15-17 ≤14 Haemophilus influenzae ≥18 Neisseria gonorrhoeae ≥38 34-37 ≤33 Pseudomonas aeruginosa ≥18 15-17 ≤14 Staphylococcus aureus ≥23 20-22 ≤19 Streptococcus pneumoniae ≥21 18-20 ≤17

Gatifloxacin 5 µg

Viridans Group Streptococci ≥21 18-20 ≤17 Enterobacteriaceae ≥20 16-19 ≤15 Haemophilus influenzae ≥18 Gemifloxacin 5 µg Streptococcus pneumoniae ≥23 20-22 ≤19 Acinetobacter spp ≥15 13-14 ≤12 Enterobacteriaceae ≥15 13-14 ≤12 Pseudomonas aeruginosa ≥15 13-14 ≤12

Gentamicin 10 µg

Staphylococcus aureus ≥15 13-14 ≤12

8

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Beta-Hemolytic Streptococci ≥19 16-18 ≤15 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥24 Neisseria gonorrhoeae ≥37 28-36 ≤27 Staphylococcus aureus ≥18 15-17 ≤14 Streptococcus pneumoniae ≥19 16-18 ≤15

Grepafloxacin 5 µg

Viridans Group Streptococci ≥19 16-18 ≤15 Acinetobacter spp ≥16 14-15 ≤13 Enterobacteriaceae ≥23 20-22 ≤19 Haemophilus influenzae ≥16 Pseudomonas aeruginosa ≥16 14-15 ≤13

Imipenem 10 µg

Staphylococcus aureus (MSSA) ≥16 14-15 ≤13 Enterobacteriaceae ≥18 14-17 ≤13 Kanamycin 30 µg Staphylococcus aureus ≥18 14-17 ≤12 Acinetobacter spp ≥17 14-16 ≤13 Beta-Hemolytic Streptococci ≥17 14-16 ≤13 Enterobacteriaceae ≥17 14-16 ≤13 Enterococcus spp ≥17 14-16 ≤13 Haemophilus influenzae ≥17 Pseudomonas aeruginosa ≥17 14-16 ≤13 Staphylococcus aureus ≥19 16-18 ≤15 Stenotrophomonas maltophilia ≥17 14-16 ≤13 Streptococcus pneumoniae ≥17 14-16 ≤13

Levofloxacin 5 µg

Viridans Group Streptococci ≥17 14-16 ≤13

9

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Beta-Hemolytic Streptococci ≥21 Enterococcus spp ≥23 21-22 ≤20 Staphylococcus aureus ≥21 ≤20 Streptococcus pneumoniae ≥21

Linezolid 30 µg

Viridans Group Streptococci ≥21 Enterobacteriaceae ≥22 19-21 ≤18 Haemophilus influenzae ≥22 Neisseria gonorrhoeae ≥38 27-37 ≤26 Pseudomonas aeruginosa ≥22 19-21 ≤18

Lomefloxacin 10 µg

Staphylococcus aureus ≥22 19-21 ≤18 Enterobacteriaceae ≥18 15-17 ≤14 Haemophilus influenzae ≥19 16-18 ≤15 Loracarbef 30 µg Staphylococcus aureus (MSSA) ≥18 15-17 ≤14

Mecillinam 10 µg Enterobacteriaceae ≥15 12-14 ≤11 Acinetobacter spp ≥16 14-15 ≤13 Burkholderia cepacia ≥20 16-19 ≤15 Enterobacteriaceae ≥23 20-22 ≤19 Haemophilus influenzae ≥20 Neisseria meningitidis ≥30 Pseudomonas aeruginosa ≥16 14-15 ≤13

Meropenem 10 µg

Staphylococcus aureus (MSSA) ≥16 14-15 ≤13 Methicillin 5 µg Staphylococcus aureus ≥14 10-13 ≤9

Acinetobacter spp ≥21 18-20 ≤17 Enterobacteriaceae ≥21 18-20 ≤17 Mezlocillin 75 µg Pseudomonas aeruginosa ≥16 ≤15 Acinetobacter spp ≥16 13-15 ≤12 Minocycline 30 µg Burkholderia cepacia ≥19 15-18 ≤14

10

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Enterobacteriaceae ≥16 13-15 ≤12 Enterococcus spp ≥19 15-18 ≤14 Neisseria meningitidis ≥26 Staphylococcus aureus ≥19 15-18 ≤14

Minocycline 30 µg

Stenotrophomonas maltophilia ≥19 15-18 ≤14 Enterobacteriaceae ≥23 15-22 ≤14 Moxalactam 30 µg Staphylococcus aureus (MSSA) ≥23 15-22 ≤14 Haemophilus influenzae ≥18 Staphylococcus aureus ≥24 21-23 ≤20 Moxifloxacin 5 µg Streptococcus pneumoniae ≥18 15-17 ≤14

Nafcillin 1 µg Staphylococcus aureus ≥13 11-12 ≤10 Nalidixic Acid 30 µg Enterobacteriaceae ≥19 14-18 ≤13

Enterobacteriaceae ≥15 13-14 ≤12 Pseudomonas aeruginosa ≥15 13-14 ≤12 Netilmicin 30 µg Staphylococcus aureus ≥15 13-14 ≤12 Enterobacteriaceae ≥17 15-16 ≤14 Enterococcus spp ≥17 15-16 ≤14 Nitrofurantoin 300 µg Staphylococcus aureus ≥17 15-16 ≤14 Enterobacteriaceae ≥17 13-16 ≤12 Enterococcus spp ≥17 13-16 ≤12 Pseudomonas aeruginosa ≥17 13-16 ≤12

Norfloxacin 10 µg

Staphylococcus aureus ≥17 13-16 ≤12 Beta-Hemolytic Streptococci ≥16 13-15 ≤12 Enterobacteriaceae ≥16 13-15 ≤12 Haemophilus influenzae ≥16 Neisseria gonorrhoeae ≥31 25-30 ≤24

Ofloxacin 5 µg

Pseudomonas aeruginosa ≥16 13-15 ≤12

11

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Staphylococcus aureus ≥18 15-17 ≤14 Streptococcus pneumoniae ≥16 13-15 ≤12 Ofloxacin 5 µg Viridans Group Streptococci ≥16 13-15 ≤12 Staphylococcus aureus ≥13 11-12 ≤10 Oxacillin 1 µg Streptococcus pneumoniae ≥20 Beta-Hemolytic Streptococci ≥24 Enterococcus spp ≥15 ≤14 Neisseria gonorrhoeae ≥47 27-46 ≤26

Penicillin 10 U

Staphylococcus aureus ≥29 ≤28 Acinetobacter spp ≥21 18-20 ≤17 Enterobacteriaceae ≥21 18-20 ≤17 Piperacillin 100 µg Pseudomonas aerugino ≥18 ≤17 Acinetobacter spp ≥21 18-20 ≤17 Enterobacteriaceae ≥21 18-20 ≤17 Haemophilus influenzae ≥21 Pseudomonas aeruginosa ≥18 ≤17

Piperacillin - Tazobactam 100/10 µg

Staphylococcus aureus (MSSA) ≥18 ≤17 Polymyxin B 300 U Pseudomonas aeruginosa ≥12 ≤11

Beta-Hemolytic Streptococci ≥19 16-18 ≤15 Enterococcus spp ≥19 16-18 ≤15 Staphylococcus aureus ≥19 16-18 ≤15 Streptococcus pneumoniae ≥19 16-18 ≤15

Quinupristin-dalfopristin 15 µg

Viridans Group Streptococci ≥19 16-18 ≤15 Enterococcus spp ≥20 17-19 ≤16 Haemophilus influenzae ≥20 17-19 ≤16 Neisseria meningitidis ≥25 20-24 ≤19

Rifampin 5 µg

Staphylococcus aureus ≥20 17-19 ≤16

12

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Rifampin 5 µg Streptococcus pneumoniae ≥19 17-18 ≤16 Staphylococcus aureus ≥19 16-18 ≤15 Sparfloxacin 5 µg Streptococcus pneumoniae ≥19 16-18 ≤15

Spectinomycin 100 µg Neisseria gonorrhoeae ≥18 15-17 ≤14 Streptomycin 10 µg Enterobacteriaceae ≥15 12-14 ≤11

Enterobacteriaceae ≥17 13-16 ≤12 Sulfonamides 250 µg Staphylococcus aureus ≥17 13-16 ≤12 Enterococcus spp ≥14 11-13 ≤10 Teicoplanin 30 µg Staphylococcus aureus ≥14 11-13 ≤10 Haemophilus influenzae ≥15 12-14 ≤11 Staphylococcus aureus ≥22 19-21 ≤18 Telithromycin 15 µg Streptococcus pneumoniae ≥19 16-18 ≤15 Acinetobacter spp ≥15 12-14 ≤11 Beta-Hemolytic Streptococci ≥23 19-22 ≤18 Enterobacteriaceae ≥15 12-14 ≤11 Enterococcus spp ≥19 15-18 ≤14 Haemophilus influenzae ≥29 26-28 ≤25 Neisseria gonorrhoeae ≥38 31-37 ≤30 Staphylococcus aureus ≥19 15-18 ≤14 Streptococcus pneumoniae ≥23 19-22 ≤18

Tetracycline 30 µg

Viridans Group Streptococci ≥23 19-22 ≤18 Acinetobacter spp ≥20 15-19 ≤14 Enterobacteriaceae ≥20 15-19 ≤14 Ticarcillin 75 µg Pseudomonas aeruginosa ≥15 ≤14 Acinetobacter spp ≥20 15-19 ≤14 Enterobacteriaceae ≥20 15-19 ≤14 Ticarcillin - Clavulanate 75/10 µg Pseudomonas aeruginosa ≥15 ≤14

13

Antimicrobial agent Disc content When testing Susceptible Intermediatelysusceptible Resistant

Ticarcillin - Clavulanate 75/10 µg Staphylococcus aureus (MSSA) ≥23 ≤22 Acinetobacter spp ≥15 13-14 ≤12 Enterobacteriaceae ≥15 13-14 ≤12 Pseudomonas aeruginosa ≥15 13-14 ≤12

Tobramycin 10 µg

Staphylococcus aureus ≥15 13-14 ≤12 Enterobacteriaceae ≥16 11-15 ≤10 Trimethoprim 5 µg Staphylococcus aureus ≥16 11-15 ≤10 Acinetobacter spp ≥16 11-15 ≤10 Burkholderia cepacia ≥16 11-15 ≤10 Enterobacteriaceae ≥16 11-15 ≤10 Haemophilus influenzae ≥16 11-15 ≤10 Neisseria meningitidis ≥30 26-29 ≤25 Staphylococcus aureus ≥16 11-15 ≤10 Stenotrophomonas maltophilia ≥16 11-15 ≤10

Trimethoprim-sulfamethoxazole 1.25/23.75 µg

Streptococcus pneumoniae ≥19 16-18 ≤15 Beta-Hemolytic Streptococci ≥19 16-18 ≤15 Neisseria gonorrhoeae ≥34 Streptococcus pneumoniae ≥19 16-18 ≤15

Trovafloxacin 10 µg

Viridans Group Streptococci ≥19 16-18 ≤15 Beta-Hemolytic Streptococci ≥17 Enterococcus spp ≥17 15-16 ≤14 Streptococcus pneumoniae ≥17

Vancomycin 30 µg

Viridans Group Streptococci ≥17 Created on 17th August, 2012 Please report any inaccuracy (if found)