Chapter 5 : Biofilm Development in Staphylococcus

Abstract:

The genus Staphylococcus consists of an ever-expanding group of gram-positive cocci that have evolved to colonize specific environmental niches, including preferential human tissues and diverse mammalian species. The study of staphylococcal biofilms in vitro has the advantage that in vivo foreign body-associated infections are often colonized by what seems to be single strains or species. The capsular polysaccharide adhesin (PS/A) was isolated from biofilm-forming S. epidermidis and shown to mediate binding of the bacteria to silastic catheter surfaces. More recently identified members of this family of autolysin/adhesins include the homologous Staphylococcus saprophyticus autolysin, Aas, which was shown to bind fibronectin and sheep erythrocytes and to exhibit bacteriolytic properties. The presence of an icaA homolog has also been inferred in S. auricularis, S. capitis, S. intermedius, S. lugdunensis, S. piscifermentans, and S. pasteuri based on DNA cross-hybridization experiments. Some of the environmental stimuli that induce biofilm formation in vitro that have been identified so far are described in this chapter. Examination of temporal and spatial gene expression patterns within a biofilm may reveal a community of cells resembling a multicellular organism, with heterogeneous roles for diverse phenotypic cell types. The problem will remain, however, that a small portion of the population may be able to survive any treatment regimen and effective therapy may have to include a combination of targets. This scenario is all the more likely when one considers the diverse and redundant biofilm-forming mechanisms already known to be present in the staphylococcal arsenal.