Session 2 Lecture Notes Flashcards
What is an endotoxin?
A toxin that is part of the bacteria structure
What is the best example of an endotoxin?
What does it contain on its outer membrane?
Gram Negative Bacteria
They contain lipopolysaccharide on their outer membrane which is highly toxic & can trigger an inflammatory response
What colour does gram negative bacteria stain and why?
Stains pink/red with the counterstain due to lipopolysaccharide outer layer
What are exotoxins?
Proteins secreted by bacteria that go out into surrounding tissue and fluid
What is an enterotoxin?
An exotoxin that acts on the bowel
What is a neurotoxin?
An exotoxin that acts on the nerves
Name the 4 main micro-organisms that cause disease in order of small to large
- Viruses
- Bacteria
- Fungi
- Parasites
What are prions?
Why can they cause problems for surgeons?
Proteins that can multiply and spread from person to person
- They cause disease and can withstand high temp and pressure (makes it hard when steralising equipment)
Which microorganism can only exist in a host cell?
Viruses
They can use bacteria as their host cell
What are the 2 layers of a virus membrane?
- Envelope - a lipid bilayer
2. Protein coat - to protect genetic material
What do the spikes on the surface of viruses do?
Allow the virus to attach to specific cell surfaces
Can viruses have DNA or RNA and does this exist as single or double stand?
Can have RNA or DNA
It can exist as single or double strand
They can also be enveloped or non-enveloped
(RNA can also be helical or icosahedral shaped)
What is the difference between positive and negative sense single stranded RNA viruses?
Positive sense single strand RNA viruses have to become negative in order to be read from and synthesise a 2nd strand
Negative sense single strand RNA viruses can be read from straight away and synthesise a 2nd strand
Why do single stranded DNA and RNA viruses synthesise a 2nd strand immediately after infecting a host cell?
Because with just 1 strand they are subject to more mutations
What is tissue trophism?
When viruses prefer certain cell lines
What is a bacteriophage?
A virus that infects and replicates within a bacterium
Do bacteria have a nuclear membrane?
No - their DNA is within the cytoplasm
How many layers does a bacteria have before you reach the cytoplasm?
3:
- Capsule - made of polysaccharides
- Cell wall - an important target for antibiotics
- Plasma membrane
What part of the bacteria is an important target for antibiotics?
The cell wall
Name three contents of bacterial cytoplasm
- Ribosomes
- Plasmids
- Nucleoid (circular double stranded DNA)
What are plasmids?
They are smaller circles of DNA that can replicable and transfer between bacteria
You may have 2 bacteria with same DNA but different plasmids
Do all bacteria have the same capsules? (outer layer of polysaccharides)
No - different strains of bacteria have different capsules (it is a virulence factor)
What are the 3 types of bacterial shape?
- Coccus shaped (circular)
- Spirillus (spiralled)
- Bacillus (square/rod shaped)
What are the two ways cocci bacteria can be arranged?
What are cocci bacteria?
- Clusters
- Chains
Cocci shaped bacteria are round/circular
What is the difference between gram negative and gram positive bacteria?
Gram positive - have peptidoglycan layer (outside plasma membrane)
Gram negative - have smaller peptidoglycans but also have an “outer layer” made of lipopolysaccharides and protein (outside plasma membrane)
What colour do gram negative and gram positive bacteria stain?
Positive - stain purple
Negative - counter stain stains red
What are aerobes and anaerobes?
Aerobes = bacteria that can survive in presence of oxygen Anaerobes = bacteria that can survive in absence of oxygen
What are spores?
Dormant form of bacteria
Give an example of a cocci gram positive bacteria
State the shape and stain colour of this bacteria
Example: streptococcus pnuemoniae
Cocci = round
Gram positive = stain purple
Give an example of a cocci gram negative bacteria
State the shape and stain colour of this bacteria
Example: Neisseria meningitidis
Cocci = round
Gram negative = counter stain red
Give an example of a bacilli gram positive bacteria
State the shape and stain colour of this bacteria
Example: Bacillus cereus
Bacilli = square/rod shape
Gram positive = stain purple
Give an example of a bacilli gram negative bacteria
State the shape and stain colour of this bacteria
Example: Salmonella typhi
Bacilli = square/rod shaped
Gram negative = counter stain red
Why might it be difficult to create an anti-viral or anti-parasitic agent?
Because they are types of eukaryotic cells
There is a risk that damage to these could also cause damage to a human cell
What are the 2 types of fungi called and are they single or multicellular?
- Yeast - single called
2. Mould - multicellular
What are the 2 types of parasites called and are they single or multicellular?
- Protozoa - single celled
2. Helminths (worms) - multicellular
What is the difference between calendar time and relative time?
Calendar time = when infections are more common at certain times of year
Relative time = when infections have certain incubation periods (time until symptoms of infection are evident)
There are 7 mechanisms of infection. Name as many as possible
- Direct contact
- Inoculation (sharps)
- Haematogenous (blood)
- Ingestion (food or drink)
- Inhalation
- Vector (insect)
- Vertical transmission (from mother to child)
What are the 3 steps you should follow to make a diagnosis?
- History
- Examination
- Inflammation
Give 2 examples of types of specific treatment and supportive treatment
Specific 1. Antimicrobials 2. Surgery Supportive 1. Symptom relief 2. Physical restoration eg oxygen
