Infections With Biofilm Formation: Selection of Antimicrobials and Role of Prolonged Antibiotic Therapy.

B are groups of bacteria attached to themselves and/or a surface and encased in a self-secreted matrix or slime. The National Institute of Health in the United States estimates that 80% of all infections are associated with organisms forming biofilms. The process driving biofilm formation from planktonic (free-swimming) bacterial populations is complex and arises as an adaptation of the bacteria to environmental cues. A general biofilm model for the formation of a bacterial biofilm can be described. In brief, the process consists of 5 genetically distinct steps: (1) initial bacterial attachment, (2) surface formation of a bacterial monolayer, (3) migration of bacteria to form microcolonies, (4) increased production of extracellular matrix and (5) maturation of the 3-dimensional architecture of the biofilm (Fig., Supplemental Digital Content 1, http://links.lww.com/INF/C438). In addition, bacterial biofilms can undergo dispersion by releasing planktonic cells, allowing for dissemination of the biofilm to other locations in the environment or the body. Biofilms are a particular concern to clinicians primarily because they contribute significantly to antimicrobial resistance, rendering these infections difficult to treat. Many studies have shown that bacterial biofilms have the ability to survive following exposure to high levels of various antibiotics. This has been attributed to a number of factors including interaction of the antibiotic with the extracellular matrix, an increase in the expression of efflux pumps during initial attachment of bacteria and the slow growth of bacteria within areas of the biofilm. As a result, biofilms are up to 1000 times more resistant to antibiotic treatment when compared with traditional, planktonic susceptibility testing. In addition, several studies have noted the inability of host immune cells to eradicate biofilm infections, resulting in a nidus for recurrent infections.