Open AccessEvaluation of Two Standardized Disk Methods for Testing Antimicrobial Susceptibility of Pseudomonas aeruginosa and of the Enterobacteriaceae
Author(s) -
Arthur L. Barry,
Lee J. Effinger
Publication year - 1974
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.6.4.452
Subject(s) - carbenicillin , gentamicin , pseudomonas aeruginosa , microbiology and biotechnology , polymyxin , agar , colistin , polymyxin b , enterobacteriaceae , agar diffusion test , biology , chemistry , antimicrobial , antibiotics , escherichia coli , bacteria , staphylococcus aureus , biochemistry , genetics , gene
Two standardized disk diffusion susceptibility testing methods were compared usingPseudomonas aeruginosa and members of theEnterobacteriaceae . The standard Bauer-Kirby method and the agar overlay method of Barry et al. were compared using carbenicillin (50- and 100-μg disks), gentamicin, polymyxin B, and colistin sulfate. Both methods gave nearly comparable zone sizes with the enteric bacilli. However, withP. aeruginosa the agar overlay method gave zones 1 to 2 mm smaller than the Bauer-Kirby method with all drugs except gentamicin. In spite of these small differences, further examination of minimal inhibitory concentration-zone size correlations indicated that the same interpretive zone standards can be applied to either diffusion technique. For testing carbenicillin againstPseudomonas sp., 50-μg disks were unsatisfactory, especially with the agar overlay method; 100-μg disks were far superior with both methods.