Hemolysis (from Greek αιμόλυση, meaning 'blood breakdown') is the breakdown of red blood cells. The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms. This is particularly useful in classifying streptococcal species. A substance that causes hemolysis is a hemolysin.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Streptococcal_hemolysis.jpg/220px-Streptococcal_hemolysis.jpg)
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Types
editAlpha-hemolysis
editWhen alpha-hemolysis (
Beta-hemolysis
editBeta-hemolysis (
The hemolysis of some weakly beta-hemolytic organisms is enhanced when streaked close to certain beta hemolytic strains of Staphylococcus aureus. This phenomenon is the mechanism behind the CAMP test[2], a test that was historically used for the identification of Streptococcus agalactiae and Listeria monocytogenes.[3] A modified version of this test, utilizing S. agalactiae instead of S. aureus, called the reverse CAMP test can also be used to identify Clostridium perfringens.
Gamma-hemolysis
editIf an organism does not induce hemolysis, the agar under and around the colony is unchanged, and the organism is called non-hemolytic or said to display gamma-hemolysis (
Hemodigestion
editWhen some otherwise non-hemolytic bacteria, such as strains of the cholera-causing bacteria, Vibrio cholerae, are plated on blood agar, no clearings are observed surrounding isolated colonies, but the blood surrounding larger areas of growth turns green. This process, called hemodigestion, is caused by the metabolic by-products of the bacteria in aerobic conditions.[4]
Notes
edit- ^ Ryan, Kenneth J.; Ray, C. George. "Chapter 25: Streptococci and Enterococci". Sherris Medical Microbiology, 6th ed. Access Medicine. Retrieved 16 August 2016.
- ^ The CAMP test is so called from the initials of those who initially described it, R. Christie, N. E. Atkins, and E. Munch-Peterson. It distinguishes Streptococcus agalactiae from the others.
- ^ Hanson, Anne (Oct 2006). "CAMP Test Protocols" (PDF). American Society for Microbiology. Retrieved 14 April 2024.
- ^ Laboratory Methods for the Diagnosis of Vibrio cholerae (PDF). Center for Disease Control and Prevention. pp. 52–54. Retrieved 16 December 2023.
References
edit- Ray, C. George; Ryan, Kenneth J.; Kenneth, Ryan (July 2004). Sherris Medical Microbiology: An Introduction to Infectious Diseases (4th ed.). McGraw Hill. p. 237. ISBN 978-0-8385-8529-0. LCCN 2003054180. OCLC 52358530.
- Kato, Gregory J.; Steinberg, Martin H.; Gladwin, Mark T. (2017-03-01). "Intravascular hemolysis and the pathophysiology of sickle cell disease". Journal of Clinical Investigation. 127 (3): 750–760. doi:10.1172/JCI89741. ISSN 0021-9738.