Pathogenicity Flashcards
What can toxins cause?
Food poisoning
Cancer
Perio
Inappropriate immune response
What is the main type of endotoxin?
LPS
Lipopolysaccharide
What are the types of exotoxin?
Pore forming
Surface acting
Intracellular
What are endotoxins produced by?
Gram negative bacteria
What are the main features of endotoxins?
Heat stable
Poorly antigenic
Cause cytokine storm and inflammation
Cause of shock and fever
How do they interact with body cells?
Lipid A of endotoxin binds to CD14 and TLR4
Produces cytokines
How do toxins damage the membrane?
Enzymes
Pore formation
Which toxins are membrane acting?
Small toxins
Proteases
Super antigens
What is a small toxin and how does it work?
Small cysteine rich protein
Produced by enterotoxics
Molecular mimicry
What do super antigens result in?
Toxic shock syndrome
Excessive activation of T cell immune response
What are the steps in intracellular toxin attack?
Cell binding
Membrane translocation
Enzymatic action
What are the most well known neurotoxins?
Botulinum
Tetanus
How do neurotoxins work?
Attack signalling across synapses
Block transmitters
What are symptoms of diphtheria?
Inflamed throat
Diphtheritic membrane in throat
Fever
What causes death from diphtheria?
Strangulation
Toxicity
How does diphtheria cause disease?
Inhibiting protein synthesis
What non-toxin diseases use type III and IV secretion systems?
Versiona pestis: plague, salmonella
Typhoid
Shigellosis
What did type III secretion system evolve from?
Flagellum
What did type IV secretion system evolve from?
Pilli
What is pathogenicity?
Ability to cause disease
What is virulence?
Degree of pathogenicity
What is a virulent bacteria?
Usually cause disease when they infect
What is a virulent factor?
Bacteria/component only involved in pathogenesis
What is a housekeeping gene?
Gee involved in all aspects of bacteria’s life
What are koch’s postulates?
Pathogen occurs in every case of disease
Pathogen does not occur in healthy subject
After isolation, pathogen can induce disease in healthy subject
What are molecular koch’s postulates?
Phenotype associated more often
Inactivation of virulent genes decrease disease
Restoration of full pathogenicity happens when mutated gene is replaced with wild type
What are virulence genes often encoded on?
Plasmids
Transposons
Bacteriophages
How do microbes adhere to surfaces?
Flagellae
Pilli
Surface proteins
What is colonisation?
Presence of microbes without accompanying disease
Define infection
Presence of microbes that results in disease
What must microbes be able to do in order to survive in their host?
Have effects on host
Evade immune defenses
Inactive immune cells
What properties of microbes aid invasion?
Enzymes
Antiphagocytic capsule and M proteins
Toxins
How can intracellular microbes invade a cell and how do they survive?
Taken into cell by phagocytosis or endocytosis
Modify phagosome compartments
Nullify host response
What are 3 examples of obligate intracellular bacterial pathogens?
Myobacterium leprae
Chlamydiaceae
Typhyus
Where does typhus replicate?
In the cytoplasm
What are some general features of obligate intracellular bacteria?
Long generation time
Exogenous energy supply
Can infect non-phagocyte cells
What are the advantages of a microbe being intracellular?
Immune evasion
Carried around body
Obtain nutrients from host
When does the immune system cause disease?
Pyogenic inflammation - acute
Can get shock from cytokine storm and organ failure
Granulomatous inflammation - chronic
Granulomas form
What is a cytokine storm?
Over activation of healthy immune system
Cause tissue damage, organ failure, shock, death
Causes sepsis
What are damages cause by immune response?
Mimicry
Cytokine induction
Toxins
