Interpretive criteria for disk diffusion tests using 5-microgram cefdinir disks with rapidly growing clinical isolates.
Preliminary interpretive zone diameter criteria were calculated for the 5-micrograms cefdinir disk diffusion test by using two potential MIC breakpoints (less than or equal to 0.5 and less than or equal to 1 micrograms/ml). The absolute agreement between tests ranged from 85.9 to 92.4%, and the false-susceptibility errors were principally contributed by the Enterobacter spp. (2.2% error). One proposed criterion was greater than or equal to 20-mm zone diameter (less than or equal to 1 micrograms/ml) for susceptibility and less than or equal to 16-mm zone diameter (greater than 2 micrograms/ml) for resistance to cefdinir. Clinical laboratory users of the disk diffusion method should be cautioned about the possibility of very major interpretive errors among enterobacter isolates.
Jones
R N
RN
Department of Pathology, University of Iowa College of Medicine, Iowa City 52242.
Erwin
M E
ME
Gooding
B B
BB
D000077525:Cefdinir; D002511:Cephalosporins / Q000008:administration & dosage / Q000494:pharmacology*; D003951:Diagnostic Errors; D004754:Enterobacter / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D005069:Evaluation Studies as Topic; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000706:statistics & numerical data
D002511:Cephalosporins; D000077525:Cefdinir