A sputum culture from a patient with whooping cough requires a medium enriched with X and V factors for the growth of Haemophilus influenzae. Which medium provides these factors by lysing red blood cells?
- A Blood agar
- B MacConkey agar
- C Chocolate agar ✓
- D Xylose lysine deoxycholate agar
Correct answer: C. Chocolate agar
Explanation
Chocolate agar is made by heating blood agar to 80°C, which lyses red blood cells and releases X factor (hemin) and V factor (NAD) into the medium. Blood agar does not lyse the cells, so V factor remains intracellular and unavailable. MacConkey and XLD do not contain these growth factors.
Reference: Ananthanarayan and Panicker's Textbook of Microbiology, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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