TABLE 4.

MIC and zone diameter discrepancy rates for 19 antimicrobial agents and 193a Acinetobacter spp.

Antimicrobial agentNo. (%)b of discrepancies
Very majorMajorMinor
Ampicillin-sulbactam19 (9.8)031 (16.1)
Piperacillin11 (5.7)026 (13.5)
Piperacillin-tazobactam18 (9.3)025 (12.9)
Ticarcillin-clavulanate10 (5.2)022 (11.4)
Ceftazidime12 (6.2)022 (11.4)
Cefepime12 (6.2)1 (0.5)25 (13.0)
Cefotaxime1 (0.5)041 (21.2)
Ceftriaxone0045 (23.3)
Ciprofloxacin009 (4.7)
Levofloxacin002 (1.0)
Gatifloxacin008 (4.1)
Gentamicin0012 (6.2)
Tobramycin1 (0.5)09 (4.7)
Amikacin01 (0.5)16 (8.3)
Tetracycline022 (11.4)62 (32.1)
Doxycycline05 (2.6)9 (4.7)
Imipenem004 (2.1)
Meropenem01 (0.5)13 (6.7)
Trimethoprim-sulfamethoxazole006 (3.1)
  • a Three isolates did not grow when tested by DD.

  • b The total population was used as the denominator. Unacceptable levels are shown in bold. They are ≥1.5% for very major errors and ≥3% for major errors, as recommended in NCCLS document M23 (12). Minor errors of ≥10% are also shown in bold.