α hemolysis
The α-hemolysis (or alpha hemolysis ) denotes a partial change of erythrocytes in a blood agar -Nährboden after colonization by streptococci of the viridans group is observed z. B. in Streptococcus pneumoniae , Streptococcus mitis , Streptococcus oralis and Streptococcus pseudopneumoniae . The α-hemolysis is therefore used for typing bacterial pathogens .
The dissolution of the erythrocytes by destroying their cell membrane is called β-hemolysis (beta-hemolysis) or complete hemolysis. This creates a light halo in the blood agar.
properties
In the process of α-hemolysis, also known as "greening", the hemoglobin in the blood agar is oxidized to methemoglobin or converted to greenish sulfhemoglobin by the metabolic products of the bacteria (usually hydrogen peroxide and hydrogen sulfide ) , which discolors the nutrient medium . The α-hemolysis is used together with the morphology of the colonies and the catalase activity for phenotypic determination. Alternatively, multiplex PCR and DNA sequencing are used for genetic determination .
Individual evidence
- ↑ LN Ikryannikova, KN Lapin, MV Malakhova, AV Filimonova, EN Ilina, VA Dubovickaya, SV Sidorenko, VM Govorun: Misidentification of alpha-hemolytic streptococci by routine tests in clinical practice. In: Infection, Genetics and Evolution . Volume 11, Number 7, October 2011, pp. 1709-1715, ISSN 1567-7257 . doi : 10.1016 / j.meegid.2011.07.010 . PMID 21798371 .
- ↑ A. Raemy, M. Meylan, S. Casati, V. Gaia, B. Berchtold, R. Boss, A. Wyder, HU Graber: Phenotypic and genotypic identification of streptococci and related bacteria isolated from bovine intramammary infections. In: Acta veterinaria Scandinavica. Volume 55, 2013, p. 53, ISSN 1751-0147 . doi : 10.1186 / 1751-0147-55-53 . PMID 23866930 . PMC 3723560 (free full text).