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E. coli is a gram-negative, facultative anaerobe, nonsporulating coliform bacterium. [18] Cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm 3. [19] [20] [21] E. coli stains gram-negative because its cell wall is composed of a thin peptidoglycan layer and an outer membrane.
Klebsiella aerogenes, [2] previously known as Enterobacter aerogenes, is a Gram-negative, oxidase-negative, catalase-positive, citrate-positive, indole-negative, rod-shaped bacterium. [3] Capable of motility via peritrichous flagella, [ 4 ] it is approximately one to three microns in length.
E. coli bacteria. Uropathogenic E. coli (UPEC) is responsible for approximately 90% of urinary tract infections (UTI) seen in individuals with ordinary anatomy. [11] In ascending infections, fecal bacteria colonize the urethra and spread up the urinary tract to the bladder as well as to the kidneys (causing pyelonephritis), [37] or the prostate ...
Unlike the general coliform group, E. coli are almost exclusively of fecal origin and their presence is thus an effective confirmation of fecal contamination. Most strains of E. coli are harmless, but some can cause serious illness in humans. Infection symptoms and signs include bloody diarrhea, stomach cramps, vomiting and occasionally, fever.
A new E. coli outbreak in 18 states has been linked to organic carrots. Here’s what to know about symptoms, recalled brands, and how to reduce your risk.
In addition, it is indole test-positive, meaning that this organism can split tryptophan to indole, pyruvate, and ammonia. M. morganii also produces urease, allowing it to break down urea. [9] Methyl red tests positive in M. morganii, an indicator dye that turns red due to the bacterium's acid production during fermentation. [7]
The species C. amalonaticus, C. koseri, and C. freundii can use citrate as a sole carbon source. Citrobacter species are differentiated by their ability to convert tryptophan to indole (C. koseri is the only citrobacter to be commonly indole-positive), ferment lactose (C. koseri is a lactose fermentor), and use malonate.
Indole test positive: appearance of pink layer at top (e.g. Escherichia coli) Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. Pure bacterial culture must be grown in sterile tryptophan or peptone broth for 24–48 hours before performing the test.