Vähemoluline

Vähemoluline is an Estonian term used in microbiology to describe bacterial isolates that cause little or no breakdown of red blood cells when grown on blood agar. It denotes low hemolytic activity, either due to the absence of hemolysis or only minimal, faint hemolysis around colonies. In practice, colonies described as vähemoluline show no clear zone of hemolysis or only a very slight clearing, making them distinguishable from fully beta-hemolytic or clearly alpha-hemolytic organisms.

In the standard framework of hemolysis testing on sheep or horse blood agar, three main patterns are commonly described: alpha-hemolysis (partial hemolysis with a greenish or dark halo), beta-hemolysis (complete clearing around colonies), and gamma-hemolysis (no hemolysis). Vähemoluline is a descriptive term that often corresponds to gamma-hemolysis or to a weakly hemolytic phenotype that does not fit neatly into the typical alpha or beta categories. Because of this, laboratories may use vähemoluline to flag isolates that require further testing to accurately determine their hemolytic behavior.

The concept is clinically relevant because hemolysis patterns aid in the preliminary identification of bacterial species. An isolate described as vähemoluline indicates limited red blood cell destruction, which can influence prioritization of confirmatory tests and interpretation of pathogenic potential. As with all phenotypic descriptions, exact classification may vary between laboratories, and additional biochemical or molecular assays are commonly used to achieve definitive identification.