Adaptive responses to antimicrobial agents in biofilms.
Bacterial biofilms demonstrate adaptive resistance in response to antimicrobial stress more effectively than corresponding planktonic populations. We propose here that, in biofilms, reaction-diffusion limited penetration may result in only low levels of antimicrobial exposure to deeper regions of the biofilm. Sheltered cells are then able to enter an adapted resistant state if the local time scale for adaptation is faster than that for disinfection. This mechanism is not available to a planktonic population. A mathematical model is presented to illustrate. Results indicate that, for a sufficiently thick biofilm, cells in the biofilm implement adaptive responses more effectively than do freely suspended cells. Effective disinfection requires applied biocide concentration that increases quadratically or exponentially with biofilm thickness.
Szomolay
Barbara
B
Department of Mathematical Sciences, Montana State University, Bozeman, MT 59717, USA.
Klapper
Isaac
I
Dockery
Jack
J
Stewart
Phil S
PS
D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D024881:Drug Resistance, Bacterial; D018869:Heat-Shock Response; D008954:Models, Biological
D000900:Anti-Bacterial Agents