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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 ...
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.
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]
Salmonella spp appear to be yellow or colourless colonies, often with a dark centre. As there are many bacteria that also look like Salmonella on DCA, it is widely recommended that more selective agars are used for the identification of Salmonella, namely xylose lysine deoxycholate (XLD) agar. This growth medium is heat-sensitive and should be ...
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]