E coli and salmonella

Question 1

E coli

1. What type of gram stain?
2. What family is E coli from?
3. motile or not?
4. shape

Answer 1

1. A Gram-negative bacterium
2. from the family Enterobacteriaceae (same as salmonella)
3. Most strains are motile via peritrichous flagella
4. Rod shaped c. 2 mm long & 0.5 mm in diameter
5. Facultative anaerobe (can grow with or without oxygen)
   • Obtains energy by oxidation & reduction of organic sources
   • Common inhabitant of the intestines of warm-blooded animals
   • Frequently a harmless commensal but some variants are adapted to cause disease

Question 2

E coli

1. Oxygen requirements
2. How des E coli obtain energy?
3. Where is it commonly found?
4. is it harmless?

Answer 2

1. Facultative anaerobe (can grow with or without oxygen)
2. Obtains energy by oxidation & reduction of organic sources
3. Common inhabitant of the intestines of warm-blooded animals
4. Frequently a harmless commensal but some variants are adapted to cause disease

Question 3

What is a virulence factor?

Answer 3

1. something that adds to the effectiveness

Question 4

Name E coli’s virulence factors

Answer 4

1. Adhesins such as pili and fimbriae that allow attachment to host cells & tissues
2. Nutrient scavenging systems to cope with hostile environments
3. Toxins-that act locally on the gut or systemically
4. Secretion systems that deliver host proteins onto surface or into host tissues to alter function/structure of host cells
5. Bacterial components that activate innate immunity- Lipopolysaccharide (LPS) from E. coli is a potent stimulator of inflammation

Question 5

How does E coli affect the dairy industry?

Answer 5

• E. coli mastitis a particular problem in housed dairy cattle over winter
• Bacteria infect udder and strong inflammatory response leads to local inflammation
• Excessive response to LPS can lead to systemic effects and death-sepsis/septic shock

Question 6

Horizontal vs vertical gene transfer

Answer 6

1. (HGT) is defined as the movement of genetic materials between distantly related organisms
2. VGT = transmission of genetic information from parent to offspring

Question 7

Horizontal gene transfer in development of virulence

Answer 7

• A major driver of pathogenic diversity in E. coli is horizontal gene transfer
• Pathogenicity Islands (PI) (or smaller Islets) are regions of DNA acquired into the genome encoding for virulence factors such as T3SS-regonised by flanking genomic repeats and different GC content
• Bacteriophage transfer of toxin genes-