Escherichia coli lecture

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Escherichia coli

Escherichia coli

Lab 4Prepared bySamira FattahAssis. Lec.College of health sciences-HMU

commonly found in the lowerintestine.

MostE. colistrainsare harmless.

fecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease.

General character:

Rod-shapeGram negativeFacultative anaerobicMotile with peritrichous flagellaSome strains are encapsulated.

Laboratory diagnosis: Specimen: Urine. pus blood stoolCSFsputum

Microscope (gram stain):Gram negative rode shape bacteria.

On blood agar

E. coli appear as medium sized, smooth, round, grayish-white colonies on blood agar.

Some strains produce beta hemolysis.

On macConkey agarthe red color of the bacterial growth indicatesE. coliisable to ferment lactose.

On EMBFerment colonies with a greenish metallic sheen.

Biochemical test

Oxidase testOxidase negative

Catalase testpositive Bubble formation

Escherichia coli motile Motility testEscherichia coliis highly motile and will show turbidity throughout the tube.

Klebsiella pneumoniaeNon motile

API test:indole test is +vegelatinase -veurease test veno H2O production

Serologic test For serotyping (Epidemiologic information)


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