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What is Quellung reaction is due to and explain in detail?
Quellung reaction: a specific test of Streptococcus pneumoniae. A suspension of Streptococcus pneumoniae is mixed with a drop of the type-specific antiserum and a spoonful of methylene blue solution. In the presence of the homologous antiserum, the capsule becomes apparently swollen, sharply delineated and refractile. The Quellung test can be done directly with sputum from acute pneumonia cases. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 225