Teicoplanin, although more active than vancomycin [by minimum inhibitory concentration (MIC)], produces smaller inhibition zones in sensitivity testing with 30-μg disks. Our data support the hypothesis that this is due to lower diffusion of teicoplanin in agar media. After 6 hr of incubation, ≈70% of vancomycin, but only 20% of teicoplanin entered the agar from a paper disk charged with 30 μg of antibiotic. This is due to a difference between the diffusion coefficients: 0.47 mm2/hr for teicoplanin and 0.72 mm2/hr for vancomycin. With the methodology used in this work, it is possible to calculate the range of concentrations of the antibiotic occurring at times likely to include the critical time-the time when the inhibition zone is formed-of most strains at any given distance from the reservoir. One can thus estimate the breakpoint diameter for a given MIC breakpoint; for example, an MIC breakpoint of ≤4 μg/ml would correspond to a ≥15-mm breakpoint diameter for vancomycin (30-μg disk) and a ≥13-mm breakpoint diameter for teicoplanin (30-μg disk).
Diffusion of teicoplanin and vancomycin in agar / L. A. Cavenaghi, E. Biganzoli, A. Danese, F. Parenti. - In: DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE. - ISSN 0732-8893. - 15:3(1992), pp. 253-258.
|Titolo:||Diffusion of teicoplanin and vancomycin in agar|
BIGANZOLI, ELIA (Secondo)
|Settore Scientifico Disciplinare:||Settore MED/01 - Statistica Medica|
|Data di pubblicazione:||1992|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/0732-8893(92)90121-9|
|Appare nelle tipologie:||01 - Articolo su periodico|