Streptococcus pyogenes

A 28-year-old woman presents with acute pharyngitis, fever, and cervical lymphadenopathy. Throat swab culture is pending. Which investigation is most appropriate to confirm Streptococcus pyogenes infection and guide immediate antibiotic therapy?

A 28-year-old woman from rural Rajasthan presents with acute onset fever, severe throat pain, and dysphagia. Throat culture grows beta-hemolytic cocci in chains. Which finding on the organism best distinguishes Streptococcus pyogenes from Streptococcus agalactiae (Group B Streptococcus)?

A 32-year-old man with a history of intravenous drug use presents with fever, new cardiac murmur, and splinter hemorrhages. Blood cultures are obtained. Which confirmatory test is most appropriate to identify Streptococcus pyogenes as the causative organism of infective endocarditis?

Streptococcus pyogenes is classified as a β-hemolytic streptococcus. Which Lancefield group does it belong to, and what is the chemical nature of the group antigen?

A 28-year-old woman presents to the emergency department with a 2-day history of severe sore throat, fever (39.5°C), and difficulty swallowing. On examination, she has exudative pharyngitis with enlarged tonsils, palatal petechiae, and tender anterior cervical lymphadenopathy. A rapid antigen detection test (RADT) for group A Streptococcus is positive. She has no history of penicillin allergy. What is the most appropriate immediate antibiotic therapy?