Streptococci Quiz

Streptococci Overview

• Gram-positive cocci bacteria, appearing in pairs or chains on Gram stain
• Catalase-negative and facultatively anaerobic
• Found in human skin, oropharynx, gastrointestinal, and genitourinary tracts

Hemolysis and Grouping

• Beta-hemolytic streptococci exhibit complete hemolysis on blood agar
• Differentiation from alpha-hemolytic streptococci based on hemolysis type
• Lancefield groups are determined by specific cell wall carbohydrate antigens
• Major groups include Group A (Streptococcus pyogenes) and Group B (Streptococcus agalactiae), which cause infective endocarditis (IE) rarely, in about 1%-2% of cases

Antibiotic Resistance and Treatment

• Resistance to penicillin is infrequently observed in S. pyogenes and S. agalactiae
• Standard treatment for beta-hemolytic streptococci IE includes penicillin, often combined with aminoglycosides

Pathogenicity of S. pyogenes

• Major human pathogen but an uncommon cause of IE
• Common causes of pharyngitis and skin infections, particularly erysipelas, and necrotizing infections

Virulence Factors

• M-protein: Fibrillar protein on cell wall that inhibits phagocytosis, aids in cell adhesion, and prevents complement fixation
• Hyaluronic acid capsule: Another significant virulence factor that serves as a barrier against phagocytosis
• Streptolysin O: Secreted toxin damaging erythrocytes and neutrophils by forming pores in their membranes, further inhibiting phagocytosis

Test your knowledge on streptococci bacteria, their characteristics, hemolysis types, and associated diseases. This quiz covers topics such as their pathogenicity, classification, and treatment options. Perfect for microbiology students and enthusiasts.