Previous Article | Next Article ![]()
Antimicrobial Agents and Chemotherapy, Nov 1996, 2517-2522, Vol 40, No. 11
PS Stewart
Antibiotic penetration into microbial biofilm was investigated
theoretically by the solution of mathematical equations describing various
combinations of the processes of diffusion, sorption, and reaction.
Unsteady material balances on the antibiotic and on a reactive or sorptive
biomass constituent, along with associated boundary and initial conditions,
constitute the mathematical formulations. Five cases were examined:
diffusion of a noninteracting solute; diffusion of a reversibly sorbing,
nonreacting solute; diffusion of an irreversibly sorbing, nonreacting
solute; diffusion of a stoichiometrically reacting solute; and diffusion of
a catalytically reacting solute. A noninteracting solute was predicted to
penetrate biofilms of up to 1 mm in thickness relatively quickly, within a
matter of seconds or minutes. In the case of a solute that does not sorb or
react in the biofilm, therefore, the diffusion barrier is not nearly large
enough to account for the reduced susceptibility of biofilms to
antibiotics. Reversible and irreversible sorption retards antibiotic
penetration. On the basis of data available in the literature at this
point, the extent of retardation of antibiotic diffusion due to sorption
does not appear to be sufficient to account for reduced biofilm
susceptibility. A catalytic (e.g., enzymatic) reaction, provided it is
sufficiently rapid, can lead to severe antibiotic penetration failure. For
example, calculation of beta-lactam penetration indicated that the
reaction-diffusion mechanism may be a viable explanation for failure of
certain of these agents to control biofilm infections. The theory presented
in this study provides a framework for the design and analysis of
experiments to test these mechanisms of reduced biofilm susceptibility to
antibiotics.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Theoretical aspects of antibiotic diffusion into microbial biofilms
Center for Biofilm Engineering, Montana State University, Bozeman 59717, USA.
This article has been cited by other articles:
Copyright © 2010 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»