chapter  13
14 Pages

Minimal Biofilm Eradication Concentration (MBEC) Assay: Susceptibility Testing for Biofilms

ByHoward Ceri, Merle E. Olson, Douglas W. Morck, Douglas G. Storey

References..............................................................................................................265

Biofilms are commonly associated with recurrent, chronic and device related infections (1-3). According to the web site of the U.S. Food and Drug Administration (FDA) more than 60% of human infections are of this type. Biofilms derived from sites of infection and those found in nature or associated with industrial processes bear striking similarities. Infectious biofilms are comprised of microbial cells within microcolonies adherent onto a surface. The surfaces may be abiotic, biotic, or the

secreted components of the host’s extracellular matrix, or a complex matrix made up of both bacterial secretions and host components (4,5). Attachment and biofilm formation affords several advantages to the infectious bacterial agent within the host. Attachment allows for the bacteria to remain within the host at a site preferential to the success of the organism, and to resist host clearance mechanisms (6). Existence within biofilms also provides a favorable energetic advantage to bacteria, awaiting nutrients to diffuse locally, rather than expending energy to seek them out. The biofilm also provides a security blanket, in context of the glycocalyx secreted by biofilms to encompass the microcolonies. This serves as a barrier against the activity of the immune system, presenting a structure too large for effective phagocytosis (4).