Cellular Microbiology and Bacterial Pathogenesis Flashcards
What are distinct features of prokaryotes?
- Absence of distinct nucleus
- DNA is in the form of a single circular chromosome
- Transcription and translation can be carried out simultaneously
Who created the first vaccine?
Edward Jenner
What is Koch’s postulates?
Important technique for determining the actual microbial cause agent of a disease
Who is Alexander Fleming?
Discovered the first antibiotic-penicillin
What is the unique parts of gram negative and gram positive bacteria?
Gram - have inner and outer membranes
Gram + have a capsule (polysaccharide)
What are the 5 groups of bacteria?
- Spherical- strep
- Rod (bacilli)- salmonella
- Spiral (spirilla) - H. Pylori
- Comma- V. Chlolera
- Corkscrew- Trepona palidum
What is the function of adherence factor?
Binding to host cells, will determine the site of colonisation. some diseases can target different areas depending on adherence factor
What are the functions of cell wall components?
Inhibit phagocytosis, escape from immune recognition, escape complement
What is the role of invasion factors?
Mediate entry into host cells
What is an endotoxin? What does it do?
A toxin that is attached to the wall of bacteria. Activates PRR (TLR4)> pro-inflammatory cytokines
What happens at high concentrations of endotoxins?
Septic shock
What do exotoxins do and what can it lead to?
Makes holes in membranes. hemolytic= causes lysis of red blood cells and kills other cells
What is salmonella?
- Foodbourne gram- rod
- different strains cause diff diseases in diff animals
- typhoid fever, food poisoning
- uses 2 type III secretion systems encoded on pathogenicity islands
- SPI-1 involved in invasion and inflammation
What is the salmonella enterica lifecycle?
- replicates within a membrane bound vacuole
- They promote the multiplication of bacteria in epithelial cells and macrophages
- Help bacteria counteract immune signalling
What is shigella?
Infection through ingestion of contaminated food or water, low inoculum.
- Induces its own uptake into epithelial cells from basal side using T3SS
- Shigella replicates rapidly in cytosol
- Actin comet tail to move within cells and from cell to cell
What is pathogenic E.coli?
- EPEC and EHEC are best studied
- Infection through contaminated food and water
- Gram -ve, extracellular
- Virulence is located on lotus of enterocyte effacement PAI
Why do bacteria target the actin cytoskeleton?
To:
- Promote entry into non-phagocytic cells
- Inhibit entry or phagocytosis in macrophages
- Move from cell to cell to spread infection
- Adhere tightly to cells
What do bacteria target in the cell?
Actin cytoskeleton
What is actin?
The skeleton and muscle of the cells, it enables: cell mobility, cell junction and cell shape etc
What is actin polymerization?
A reversible process in which monomers both associate and dissociate from ends of actin filaments
What do GTPase activating proteins do?
Catalyse GTP hydrolysis by the GTPase> this inactivates the protein
What do GTPase activating proteins do?
Catalyse GTP hydrolysis by the GTPase> this inactivates the protein
What are phagocytes?
Cells that protect the body by ingesting harmful bacteria and dead or dying cells by phagocytosis
What are the steps of phagocytosis?
- Binding
- Internalisation
- Degradation
