Immuno - Microbial Infection Flashcards
What are the 5 main types of infectious agents?
- Viruses
- Bacteria
- Fungi
- Protozoa
- Helminths (parasites)
What are viruses?
Obligate parasite - only survive by infecting other cells (not cells in their own right)
How does viruses contain genetic material?
RNA/DNA
What is host specificity?
Capability of infecting one or more specific hosts
How do viruses come out of cells?
- Budding out of cell - host cell remains intact (Enveloped virus)
- Cytolysis - host cell ruptures (Non-enveloped virus)
What are the routes of infection for viruses?
- Faecal-oral
- Airborne
- Insect vectors
- Blood borne
What is are examples of viruses?
- HIV - Retrovirus
- Polio
- HPV - human papilloma virus
- Smallpox - Variola virus
(Eradicated) - Influenza
- Rhinovirus
- Adenovirus
- Coronavirus
What are bacterias?
Prokaryotes
What are the characteristics of a prokaryote?
- No internal membranes (except non-pathogenic photosynthetic bacteria)
- HAPLOID (single copy of chromosome)
- cytoskeleton poorly defined
What is the main structural determinant of prokaryotes?
The cell wall that contains peptidoglycan
How do prokaryotes divide?
Binary fission (exponential increase)
How would haploid gene of prokaryote affect mutation effect?
Only that one gene mutated to have bigger phenolytic effect
How do viruses replicate?
- Binding
- Fusion
- Reverse transcriptase
- Integration with host DNA
- Transcription
- Translation into particle
- Assembly
What use are the structures on bacteria?
*Note not all bacterias have these features
- Pilus (adhere to surfaces)
- Capsule (Prevent desiccation/hinder phagocytosis)
- Flagella (swimming)
What are examples of bacterias?
- Shigella
- Mycobacterium tuberculosis (TB)
- Neisseria Meningitidis (Commensal to pathogen)
- Hospital-acquired infections (Nosocomial)
- Helicobacter pylori
- E. coli
What is Shigella?
Invasive pathogen via faecal-oral transmission that affects the GI tract
- it moves without flagella by being pushed by host actin
How does shigella bacteria get pushed around by host actin?
It nucleates host actin at tail of bacteria therefore push forward into cytoplasm of neighbouring cells
(infects whole monolayer of cells without going outside)
What are serogroups?
A group of bacteria containing a common antigen
Where and how does Neisseria meningitidis affect the body?
- Colonisation in naso-pharynx (no harm)
- Community acquired multiple serogroups - (invade tissues - non-blanching rash)
- Septicaemia
- Meningitis (penetrate blood-brain barrier - found in cerebrospinal fluid)
What is Septicaemia?
Fatal rapid progressing bacterial disease
- Go into septic shock
- Severe inflammatory response
What is non-blanching rash caused by?
Neisseria meningitidis - rapid onset needing immediate medical attention
- Can be left with severe disabilities
- Common (babies, young adult)
- Vaccine is available for different serogroups
What are some hospital-acquired infections (bacteria)?
- Clostridium difficile
- MRSA - Methicillin Resistant Staphylococcus aureus
Why are hospital-acquired bacterial infections so difficult to treat?
A lot of AMR - Antimicrobial resistance
What diseases do Helicobacter pylori cause?
- Peptic ulcer
- Gastric cancer
Why do some pathogens mutate so quickly even with similar mutation rates as humans?
Have short replication/generation time
What are mutation rates?
How quickly a novel trait is developed
Why do viruses mutate so quickly?
Error prone replication (Low efficiency correction)
How is pathogenic E.Coli spread?
Originate in animals
Spread via faecal-oral route
What is the current problem with TB?
- Drug therapy take too long
- BCG vaccine don’t work well in endemic regions
- Current diagnostics miss too many cases (fail to break transmission chain)
What can we improve with TB treatment?
- New drugs (shorten treatment)
- Better vaccines
- Better tools for early diagnosis (Imaging tools eg PET-CT scan [high resolution] show area of inflammation - help understand pathogenesis of TB)