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Table 1 Mean differences of zone diameters measurements as determined by calliper and Sirscan on-screen adjusted

From: Standardisation of disk diffusion results for antibiotic susceptibility testing using the sirscan automated zone reader

Drug or drug class   Zone diameter mean difference (mm)  
  Gram-negative rods Staphylococcusspp. Enterococcusspp.
Penicillins 0.9 1.4 2.5
Cephalosporins 1   
Carbapenems 1.4   
Aminoglycosides 0.6 1.3  
Quinolones 0.9 1.4  
Trimethoprim-Sulfamethoxazole 0.8 0.9  
Rifampicin   1.1  
Glycopeptides    0.8
Cefoxitin   0.7  
Clindamycin   1.6  
All antibiotics 0.9 1.2 1.7
  1. Antibiotic drug classes / drugs tested for Gram-negative rods comprised ampicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam (Penicillins), cefuroxime, cefpodoxime, ceftriaxone, ceftazidime, cefotaxime, cefepime, cefoxitin, (cephalosporins), ertapenem, imipenem, meropenem (carbapenems), amikacin, gentamicin, tobramycin (aminoglycosides), nalidixic acid, ciprofloxacin, levofloxacin (quinolones), and trimethoprim-sulfamethoxazole. Antibiotic drug classes / drugs tested for Staphylococcus spp. comprised penicillin (penicillins), cefoxitin, amikacin, gentamicin, tobramycin (aminoglycosides), ciprofloxacin, levofloxacin (quinolones), rifampicin, erythromycin, clindamycin, and trimethoprim-sulfamethoxazole. Antibiotic drugs tested for Enterococcus spp. comprised ampicillin (penicillins) and vancomycin (glycopeptides).