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haemolysins, leukocidin, and perhaps of less significance, beta and gamma
hemolysins. Certain strains of Staphylococcus aureus are capable of producing other
damaging toxins such as enterotoxins and exfoliatin, and the toxin responsible for
the toxic shock syndrome. The enzyme coagulase is regarded as a virulence factor
in that it may inhibit the bactericidal activity of normal serum and phagocytosis.
Staphylococcus aureus lipase may influence the non-specific, primary defense
system by increasing the chemotactic response of polymorph nuclear leukocytes.
The ability of Staphylococcus aureus to bind fibronectin and collagen exposed in
open wounds in microtrauma allow this organism to readily establish itself in
traumatized tissues.
Binding to laminin allows this species to localize in basal membranes in various body
sites. Staphylococcal pathogenicity also depends upon the effectiveness of the host
defense system, which include natural barriers of the skin and mucous membranes,
and humoral and phagocytic immune responses. During the past decade, it has
become increasingly apparent that patients with deficient numbers of phagocytic
cells, or disorders in their function, have increased susceptibility to staphylococcal
infections. Members of the genus Staphylococcus are Gram-positive cocci that occur
singly, in pairs, tetrads, short chains and irregular grapelike clusters. These
members are non-motile, non-spore-forming, and usually unencapsulated, or have
limited capsular formation. Staphylococcus aureus grows rapidly and abundantly
under aerobic conditions. Staphylococcal cell walls contain teichoic acid and
peptidoglycan. They can be grouped according to their natural or genomic
relationships as dertemined by DNA-DNA hybridization and the thermal stability of
DNA heteroduplexes (Willey et al. 2008).
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