key term - Group A strep

Definition

Group A strep (Streptococcus pyogenes) is a gram-positive bacterium that causes various infections in humans. It is characterized by its ability to form chains and produce numerous virulence factors.

5 Must Know Facts For Your Next Test

1. Group A strep is a gram-positive, beta-hemolytic bacterium that appears in chains under the microscope.
2. It is responsible for diseases such as pharyngitis, impetigo, and rheumatic fever.
3. The cell wall of Group A strep contains a unique carbohydrate antigen known as the Lancefield group A antigen.
4. It produces several virulence factors including streptolysins, M protein, and hyaluronic acid capsule which help it evade the host immune system.
5. Penicillin remains the antibiotic of choice for treating infections caused by Group A strep.

Review Questions

Related terms

Gram-Positive Bacteria: Bacteria that retain the crystal violet stain used in Gram's method and appear purple under a microscope due to their thick peptidoglycan layer.

Beta-Hemolysis: A complete lysis of red blood cells on a blood agar plate, resulting in a clear zone surrounding bacterial colonies.

Virulence Factors:

Molecules produced by pathogens that contribute to the pathogenicity and facilitate infection or damage to the host.