Reports from the laboratory providing results of the standard single-disk susceptibility test with a 300-µg nitrofurantoin disk should be interpreted according to the following criteria: Zone Diameter (mm) Interpretation 17 Susceptible (S) 15-16 Intermediate (I) 14 Resistant (R) Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for nitrofurantoin. As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the 300 µg nitrofurantoin disk should provide the following zone diameters in these laboratory test quality control strains: Microorganism Zone Diameter (mm) E. coli ATCC 25922 20-25 S. aureus ATCC 25923 18-22 | ||||
Email this article
Printer friendly
Bookmark this pageadvertisement
