What is quellung reaction?

Quellung reaction, also known as capsular swelling reaction, is a laboratory test used to identify the presence of bacterial capsules. Bacterial capsules are protective outer layers that surround some bacteria, helping them evade the immune system and resist antibiotics.

The quellung reaction involves mixing a small amount of bacterial suspension with specific antibodies that target the capsule. If the bacteria have a capsule, the antibodies will bind to the capsule and cause it to swell or become visible under a microscope. This reaction is often used to identify Streptococcus pneumoniae, which is a common cause of pneumonia and meningitis.

The quellung reaction is a valuable tool for diagnosing bacterial infections and determining the serotype of a bacterial strain. It can also help researchers study the virulence and pathogenicity of different bacterial species.

Overall, the quellung reaction is a simple and reliable method for detecting bacterial capsules and is commonly used in microbiology laboratories worldwide.