A sputum culture on 5% sheep blood agar shows colonies surrounded by a greenish, opaque zone. The organism is optochin-sensitive. What type of hemolysis is demonstrated?
- A Gamma hemolysis
- B Beta hemolysis
- C Alpha hemolysis ✓
- D Double zone hemolysis
Correct answer: C. Alpha hemolysis
Explanation
Alpha hemolysis is a greenish discoloration around colonies due to partial lysis of red blood cells and conversion of hemoglobin to methemoglobin. Beta hemolysis is a clear zone of complete lysis. Gamma hemolysis means no change. The vignette describes Streptococcus pneumoniae, which characteristically shows alpha hemolysis and is optochin-sensitive.
Reference: Jawetz, Melnick, & Adelberg's Medical Microbiology, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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