Group A Streptococcal Adherence

Excerpt

Streptococcus pyogenes (group A streptococci) is an exclusive human pathogen that causes a wide range of infections, from acute pharyngitis and impetigo to life-threatening necrotizing fasciitis. The attachment of S. pyogenes to the pharyngeal and skin epithelial cell surfaces represents a critical first step in establishing such infections. While the importance of particular surface-exposed adhesins tends to be serotype- or infection-model–specific, adherence to human cells is generally regarded as a two-step process. The first step involves a relatively weak interaction mediated by lipoteichoic acid that allows the bacteria to overcome electrostatic repulsion. This initial interaction is followed by a stronger, more specific, and irreversible binding of a variety of tissue-specific protein or carbohydrate receptors to streptococcal surface molecules. This chapter reviews a number of the well-characterized streptococcal adherence mechanisms and will summarize some of the major advances that have been made in our understanding of this initial stage of infection.