Escherichia Coli

Question 1

Characteristics of Escherichia Coli

Answer 1

عندها اي حاجة ● Cell Wall

● Capsule

● Flagella

“Has all three antigens (O,H & K antigen)”

● Is a lactose fermenter

● It’s used to detect the faecal contamination of water :by EMP (give green sheen

)عندھا اي حاجة( :It is a typical bacteria

Question 2

Types of pathogenicity islands and diseases causes

Answer 2

A = Causes Diarrhoea
B = Causes UTI
C = Causes Neonatal Meningitis

Question 3

➢Virulence factors Escherichia Coli

Answer 3

● Antiphagocytic capsule.

● Pilli.

● Toxins

a. Hemolysin

b. Diarrheal toxins

c. Endotoxin
للتفاصيل 👇👇👇

a. Hemolysin: Found in strains causing UTI (type B) (mcqs)

• These strains must also have pilli to cause UTI

b. Diarrheal toxins:

● Shiga-like toxin: Inhibit protein synthesis by removing Adenine from 28S Causes: Dysentery and hemolytic uremic syndrome (HUS)

● Heat labile toxin: increase cAMP. Causes: Watery diarrhoea

104 ● Heat stable toxin: increase cGMP. Causes: Watery diarrhoea c. Endotoxin : Causes septic shock.

Question 4

➢Clinical manifestations of E. coli

Answer 4

● Local: Diarrhea

● Systemic: UTI, Neonatal Meningitis ،Wound infection ،Septicaemia

شوفي التفاصيل في الشيت عليييييك الله لانها مهمممممة🙌

Question 5

➢Diagnosis of E. coli

Answer 5

طولي بالك 🤌🤌🤌🤌🤌🤌
1. Specimen collection:

Depends on the site of the infection.

● Diarrhoea: stool.

● UTI: midstream urine.

● Meningitis: CSF.

● Wound infection: wound swap.

● Septicaemia: Blood sample.

2. Microscopy:

● Gram -ve bacilli with flagella.

● In Shigella usually we don’t find it but we found RBCs and Pus cells in stool. But in E.Coli we find the bacteria itself.

3. Culture:

● MacConkey agar: pink colonies because it’s lactose fermenter

● EMB agar: gives green sheen and is used to detect fecal contamination of water (water cleanness).

● Sorbitol MacConkey agar [SMaC]: to differentiate Entero-hemorrhagic E-coli from other stains (EHEC does not ferment sorbitol)

● Verotoxigenic E-Coli can be cultured in cell cultures (not important)

4. Biochemical tests: MIO:

● Motility: +ve.

● Indol: +ve.

● Oxidase: -ve.

Question 6

➢Treatment E. coli

Answer 6

● Neonatal Meningitis: Ampicillin

● UTI: Ciprofloxacin

● Diarrhea: Rehydration. But if severe we give Ciprofloxacin.

● Hemolytic uremic syndrome: No antibiotic treatment but we do renal dialysis.

Question 7

Hoe enterotoxoginc toxin work

Answer 7

Increase activation of guanylate