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Hemolyses of Streptococcus spp. (left) α-hemolysis (S. mitis); (middle) β-hemolysis (S. pyogenes); (right) γ-hemolysis (non-hemolytic, S. salivarius) 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.
Proteus species do not usually ferment lactose. Similar to other members of the Enterobacterales order, bacteria from the Proteus genus are glucose fermenting, oxidase-negative, catalase-positive, and nitrate-positive. Glucose fermentation in this species can be demonstrated through the triple sugar iron test.
Morganella morganii is a species of Gram-negative bacteria. [2] It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. [ 2 ] Although M. morganii has a wide distribution, it is considered an uncommon cause of community-acquired infection, and it is most often encountered in postoperative ...
The swarming capability of Proteus mirabilis is important because it is implicated in the pathogenesis of the bacteria and the swarming capability is associated with the bacteria's ability to express virulence factors [9] Proteus mirabilis has a very characteristic bulls-eye appearance on an agar plate due to the regular periodic cycling ...
One particular feature of this type of motility is the formation of dendritic fractal-like patterns formed by migrating swarms moving away from an initial location. Although the majority of species can produce tendrils when swarming, some species like Proteus mirabilis do form concentric circles motif instead of dendritic patterns. [19]
Pseudomonas species also typically give a positive result to the oxidase test, the absence of gas formation from glucose, glucose is oxidised in oxidation/fermentation test using Hugh and Leifson O/F test, beta hemolytic (on blood agar), indole negative, methyl red negative, Voges–Proskauer test negative, and citrate positive. [citation needed]
Chocolate agar is a type of blood agar plate in which the blood cells have been lysed by heating the cells to 80 °C. It is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae. Chocolate agar is named for its color, and no chocolate is contained in the plate.
Streptolysin O is an oxygen-sensitive cytotoxin, secreted by most group A Streptococcus (GAS), and interacts with cholesterol in the membrane of eukaryotic cells (mainly red and white blood cells, macrophages, and platelets), and usually results in beta-hemolysis under the surface of blood agar. Streptolysin S is an oxygen-stable cytotoxin also ...