Notes on Streptococcus Pyogenes Lecture

Introduction to Streptococcus Pyogenes

• Name Origin: Derived from Greek; 'pyo' means pus, indicating association with pus formation.
• Structure: Round cocci bacteria in long chains (strepto = strip).
• Classification: Member of Group A strep, classified by surface proteins.
• Gram-Positive Cocci: Similar to Staph aureus but forms chains, not clusters.
• Carriers: Found in 5-15% of children, typically asymptomatic.

Diseases Caused by Streptococcus Pyogenes

• Range of Diseases: From mild skin infections to severe systemic diseases.
• Antibiotic Sensitivity: Highly sensitive to penicillin, unlike Staph aureus.
• Global Impact: 700 million infections annually, with a severe case mortality rate of 25%.
• Primary vs. Secondary Infections: Can make healthy people sick (primary) but often seen as secondary infections, e.g., following chickenpox.

Specific Infections and Concerns

• Strep Throat: Common primary infection; symptoms include sore throat, fever, white streaks on tonsils.
• Secondary Infections: Can be aggravated by other conditions like chickenpox.
• Invasive Infections: Potential for necrotizing fasciitis (flesh-eating disease), cellulitis, and toxic shock syndrome.
• Complications: Can lead to rheumatic fever and post-streptococcal glomerulonephritis.

Transmission and Prevention

• Transmission: Direct contact, respiratory droplets, sharing drinks.
• Seasonality: Respiratory infections more common in winter; skin infections in summer.
• Prevention: Handwashing, avoiding extended tampon use, and early antibiotic treatment.

Treatment

• Antibiotics: Penicillin and other oral antibiotics; early intervention crucial.
• Surgical Intervention: Required for severe cases like necrotizing fasciitis.

Epidemiology and Testing

• Invasiveness: Some strains becoming more virulent.
• Global Presence: Infections worldwide, particularly in children.
• Diagnosis: Rapid strep tests available; quick throat swab test for Group A strep.

Toxin Production

• Scarlet Fever: Caused by erythrogenic toxin from certain strains.
• Toxic Shock Syndrome: Superantigen toxins causing overactive immune response.

Historical Context

• Childbed Fever: Historical significance as a cause of maternal mortality due to poor hygiene practices in hospitals.
• Rheumatic Fever: Decreasing in developed countries due to effective antibiotic use.