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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 ...
Proteus mirabilis appears as Gram-negative rods after Gram staining under bright-field microscopy with 1000 times magnification. Proteus mirabilis is a Gram-negative, facultatively anaerobic, rod-shaped bacterium. It shows swarming motility and urease activity. P. mirabilis causes 90% of all Proteus infections in humans.
This picture was taken against a lightsource to make the dendrites (white branched structures) clearly stand out. Swarming motility is a rapid (2–10 μm/s) and coordinated translocation of a bacterial population across solid or semi-solid surfaces, [ 1 ] and is an example of bacterial multicellularity and swarm behaviour .
Unlike the more commonly seen species of Proteus, P. hauseri is also able to convert tryptophan into indole, resulting in a positive indole test. P. hauser i shares a similar biochemical profile with Proteus vulgaris but can be differentiated by its ability to produce acid from trehalose.
The viridans streptococci are a large group of commensal streptococcal Gram-positive bacteria species that are α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), although some species in this group are actually γ-hemolytic, meaning they produce no change on blood agar. [1]
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.