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. 1974 Oct;6(4):452–459. doi: 10.1128/aac.6.4.452

Evaluation of Two Standardized Disk Methods for Testing Antimicrobial Susceptibility of Pseudomonas aeruginosa and of the Enterobacteriaceae

Arthur L Barry 1,2, Lee J Effinger 1,2
PMCID: PMC444670  PMID: 4157344

Abstract

Two standardized disk diffusion susceptibility testing methods were compared using Pseudomonas aeruginosa and members of the Enterobacteriaceae. 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, with P. 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 against Pseudomonas sp., 50-μg disks were unsatisfactory, especially with the agar overlay method; 100-μg disks were far superior with both methods.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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