Quellung Reaction

                   
                                                 Quellung is the German word for "Swelling"

The pneumococcal quellung reaction was first described in 1902 by the scientist Fred Neufeld, and applied only to Streptococcus pneumoniae, both as microscopic capsular swelling and macroscopic agglutination (clumping visible with the naked eye)


The quellung reaction, also called the Neufeld reaction, is a biochemical reaction  in which antibodies  bind to the bacterial capsule of Streptococcus pneumoniae, Klebsiella pneumoniae, Neisseria meningitidis, Bacillus anthracis, Haemophilus influenzae, Escherichia coli, and Salmonella. 


The antibody reaction allows these species to be visualized under a microscope. If the reaction is positive, the capsule becomes opaque and appears to enlarge.


It was initially an intellectual curiosity more than anything else, and could distinguish only the three pneumococcal serotypes known at that time. However, it acquired an important practical use with the advent of serum therapy to treat certain types of pneumococcal pneumonia in the 1920s because selection of the proper antiserum to treat an individual patient required correct identification of the infecting pneumococcal serotype, and the quellung reaction was the only method available to do

                                                                         
                               Encapsulated Bacteria: Capsule Swells:  + Quellung Reaction

Quellung and Streptococcus Pneumonia

Pneumonia and Europe

Germany Must Find Swollen Faces With Quellung Reaction

Snapshot

Animals Swell