Quellung reaction
The quellung reaction, also called the Neufeld reaction, is a
Quellung is the German word for "swelling" and describes the microscopic appearance of
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).[2] 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 this. Dr. Albert Sabin made modifications to Neufeld's technique so that it could be done more rapidly,[3] and other scientists expanded the technique to identify 29 additional serotypes.[4]
Application of Neufeld’s discoveries to other important areas of research came when
Serum therapy for infectious diseases was displaced by antibiotics in the 1940s, but identification of specific serotypes remained important as the understanding of the epidemiology of pneumococcal infections still required their identification to determine where different serotypes spread, as well as the variable invasiveness of different serotypes. Understanding the prevalence of various serotypes was also critical to the development of pneumococcal vaccines to prevent invasive infections.
The quellung reaction has been used to identify the 93 known capsular serotypes of Streptococcus pneumoniae in diagnostic settings, but in recent years it has been challenged by the latex agglutination method, and further by molecular typing techniques such as the polymerase chain reaction, which detect DNA and therefore target genetic differences between serotypes.[7] Currently, there are 100 known capsular serotypes.[8]
References
- ISBN 978-0-7817-8215-9.
- S2CID 1143320.
- .
- PMID 16694257.
- PMID 20474956.
- PMID 19871359.
- Center for Disease Control. Retrieved October 22, 2010.
- ^ "GPS :: Global Pneumococcal Sequencing Project". www.pneumogen.net. Retrieved 2021-10-09.
Further reading
- Park, I. H., Pritchard, D., Cartee, R., Brandao, A., Brandileone, M. and Nahm, M. Discovery of a new capsular serotype (6C) within serogroup 6 of Streptococcus pneumoniae. Journal of Clinical Microbiology. 2007;45:1225–1233.
- Pai, R; Gertz, R. E.; Beall, B. (2006). "Sequential multiplex PCR approach for determining capsular serotypes of Streptococcus pneumoniae isolates". Journal of Clinical Microbiology. 44: 124–131. S2CID 86648528.
- Austrian, R (1976). "The Quellung Reaction, a Neglected Microbiologic Technique". Mount Sinai Journal of Medicine. 43 (6): 699–709. PMID 13297.