| 1. NCBI Taxonomy ID: |
| 1314 |
| 2. Disease: |
| Group A streptococcal infections, Strep throat, Scarlet fever |
| 3. Introduction |
| Streptococcus pyogenes is a spherical gram-positive bacterium that grows in long chains and is the cause of Group A streptococcal infections. S. pyogenes displays streptococcal group A antigen on its cell wall. S. pyogenes typically produces large zones of beta-hemolysis (the complete disruption of erythrocytes and the release of hemoglobin) when cultured on blood agar plates and are therefore also called Group A (beta-hemolytic) Streptococcus (abbreviated GAS). S. pyogenes is the cause of many important human diseases ranging from mild superficial skin infections to life-threatening systemic diseases. Infections typically begin in the throat or skin. Examples of mild S. pyogenes infections include pharyngitis ("strep throat") and localized skin infection ("impetigo"). Erysipelas and cellulitis are characterized by multiplication and lateral spread of S. pyogenes in deep layers of the skin. S. pyogenes invasion and multiplication in the fascia can lead to necrotizing fasciitis, a potentially life-threatening condition requiring surgical treatment (Wiki: S. pyogenes). |
| 4. Microbial Pathogenesis |
|
Colonization of tissues by S. pyogenes is thought to result from a failure in the constitutive defenses (normal flora and other nonspecific defense mechanisms) which allows establishment of the bacterium at a portal of entry (often the upper respiratory tract or the skin) where the organism multiplies and causes an inflammatory purulent lesion (Textbook of Bacteriology). |
| 5. Host Ranges and Animal Models |
| S. pyogenes is a human pathogen and mice are the animal model that is used (Okamoto et al., 2005). |
| 6. Host Protective Immunity |
| Macrophages and the antibody mediated response are the major defenses for host protective immunity against S. pyogenes infection (Textbook of Bacteriology). |
