Welcome to the MedLibrary.org Wikipedia Supplement on Hemolysis (microbiology) -- Please Click to Return to Front Page

Examples of alpha (top), beta (middle), and gamma (bottom) hemolysis on sheep blood agar plates

Hemolysis 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 a particularly useful in classifying streptococcal species. A substance that causes hemolysis is a hemolysin.

Types of hemolysis

• When Alpha hemolysis (α-hemolysis) is present the agar under the colonies is dark and greenish. Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha hemolysis. This is sometimes called green hemolysis because of the color change in the agar. Other synonymous terms are incomplete hemolysis and partial hemolysis. Alpha hemolysis is generally caused by peroxides produced by the bacterium.

• Beta hemolysis (β-hemolysis), sometimes called complete hemolysis, is a complete lysis of red cells in the media around and under the colonies: the area appears lightened and transparent. Streptococcus pyogenes, or Group A beta-hemolytic Strep (GAS), displays beta hemolysis.
  • Some weakly beta-hemolytic species cause intense beta hemolysis when grown together with a strain of Staphylococcus. This is called the CAMP test¹. Streptococcus agalactiae displays this property. Clostridium perfringens can be identified presumptively with this test.

• If an organism does not induce hemolysis, it is said to display gamma hemolysis (γ-hemolysis): the agar under and around the colony is unchanged (this is also called non-hemolytic). Enterococcus faecalis (formerly called Group D Strep) displays gamma hemolysis.

Notes

¹The CAMP test is so called from the initials of those who initially described it, R. Christie, N. E. Atkins, and E. Munch-Peterson.

References

• Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9. 

Wikipedia content modification information:

• This page was last modified on 6 October 2008, at 18:10.

Wikipedia Authorship and Review

Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.

Wikipedia Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Hemolysis (microbiology)".

The URL for this specific entry is:

• http://medlibrary.org/medwiki/Hemolysis_(microbiology)

All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.