Hello everyone,now i would like to continue tell about the remaining part of E.coli in this post as we already discussed about some strains in and its repsonse to biochemical reactions.
The remaining strains are-
4)EHEC - here H means Haemorrhagic.the strain is "O157:H7".the infective dose is very low to cause infection it's about less than 100 CFU/ml.it causes Haemolytic uremic syndrome and haemorrhagic cystitis.
5)EAEC - here A means Aggregative.strain is O104:H4.on Hep2 cell line it gives "stacked brick appearance".it releases EAST1 toxin and causes persistent diarrhea.
6)DAEC - It is Diffusely Adherent E.coli and gives diffuse pattern on cell line.
Toxins
These are the toxins released by E.coli-
Heat labile toxin - LT
Heat stable toxin - ST
Verocyte shiga like toxin - VST
Mechanism of action -
Heat labile toxin- LT has two fragments- fragment 'A' and fagmnet 'B' and increases CAMP and causes diarrhea.
Heat stable toxin - ST acts by increasing CGMP levels.
Important point to note-
All strains of E.coli ferment sorbitol except EHEC it doesnot ferment sorbitol and gives pale colonies on sorbitol-macconkey agar.
Diagnosis
Sample - urine(mid stream sample)
Culture - CLED
Criteria to diagnose - it was given by kass
Signicant bacteruria or asymptomatic bacteruria - >10⁵ CFU/ml
Catheter associated UTI - >10³ CFU/ml
Catheter associated asymptomatic bacteruria - >10² CFU/ml
Indole test - +ve
Methyl red test - +ve
VP test - -ve
Citrate - -ve
Hope it may helpful to you.
Thanks for reading,
Yours @summisimeon