Table 1.

Characteristics of study isolates and susceptibility test results of participating laboratories listed by interpretive categorya

Antimicrobial agent testedCT-6 (E. coli producing SHV-8)CT-7 (E. coliproducing AmpC)CT-8 (K. pneumoniae producing SHV-4)CT-9 (K. pneumoniae producing SHV-5)CT-10 (K. pneumoniae susceptible control)
Ref MICbNo. of laboratories obtaining a result of:Ref MICNo. of laboratories obtaining a result of:Ref MICNo. of laboratories obtaining a result of:Ref MICNo. of laboratories obtaining a result of:Ref MICNo. of laboratories obtaining a result of:
SIRSIRSIRSIRSIR
Ceftazidime>128012212800231280716>12803200.252001
Cefotaxime810016445216641326230.121000
Ceftriaxone161340128764164933211140.121500
Aztreonam1632032122128005>1280060.12500
  • a S, susceptible; I, intermediate; R, resistant.

  • b Ref MIC, reference MIC (in micrograms per milliliter) determined by the NCCLS broth microdilution method.