Bacteria And Viruses Flashcards
What does a pathogen do in the progression from asymptomatic to symptomatic infection?
It spreads, multiplies and causes damage.
If a pathogen enters a persons normal microbiota what can be said about that person?
They are a carrier of that pathogen.
What is often the reservoir in an infection?
Another animal species.
How can we reduce hospital infections?
Remove stages 1 or 2
1 - reservoir
2 - immediate source.
This includes HCWs washing hands thoroughly and isolation of infectious patients.
What is R0 and what does it tell us?
R0 is the rate at which infection causes colonisation in uninfected individuals. If R0>1 then infection propagates. If R0
What name do we give to a microorganism which is incapable of producing disease and lives in the body naturally?
Non-pathogen
Define pathogen.
A microorganism such as virus, bacteria, yeast or fungi which parasitises an animal or human producing disease.
What is antibiotic resistance?
This is where a person may not complete a course of antibiotics and so all the weak bacteria have been killed and the stronger ones remain, maybe one with a resistant gene. These multiply and then a new strain of the bacteria form which all have the resistant gene. This gene can be passed by conjugation and horizontal gender transmission to the bacteria strains.
What is the difference between an infection and an infectious disease?
Infection is the invasion and multiplication of bacteria/viruses in the body. Infectious disease is where this causes a disorder.
What is the normal microbiota?
Aggregation of microorganisms found on the surface/ deep skin.
What is a commensal infection?
This is when one organism benefits from another, without the other being affected.
What does gram staining tell us about the properties of bacteria?
It tells us how thick the peptidoglycan cell wall is. The thick wall does not allow extraction of the crystal violet and so this is gram positive.
Name two internal features which bacteria can posses.
Spores
Granule
What is a fimbriae which can be found on bacteria?
It is a tail on the cell/pilli where exchange of DNA can take place.
Give two reasons why bacterial cell walls are clinically important
They allow detection and diagnosis via acid fast and gram stains.
They are the target for antibiotics.
What is a bacterial biofilm?
This is where bacterial agent infect intravascular devices such as cannulas.
What is required for bacterial growth?
An energy source, building blocks and an appropriate atmosphere.
What is a virus?
A virus is a microorganism but is much smaller than bacteria. It has to use the mechanisms of the host cell in order to survive.
What molecule do enveloped viruses contain?
Lipids. These are more susceptible to disinfectants compared to non-enveloped viruses.
Comment on the difference in growth rate between bacteria and viruses.
Bacteria show exponential growth, whilst viruses show incredibly rapid growth. When a cell bursts, many viruses are released.
What is the difference between +RNA and -RNA in viruses?
+RNA can act as mRNA and can therefore produce proteins.
A Virion is an entire virus particle. What two components is it made up from?
Inner nucleic acid core.
Outer protein shell which is called the capsid. This protects the inner nucleic acid core and can be involved in attachment to host cells.
What is syncytia formation which can occur in viral infections?
This is where multi nucleated cells form by fusion of plasma membranes.
Explain how retroviruses can cause cancer.
Retroviruses turn on the cells oncogenes causing it to replicate uncontrollably.
Explain how DNA viruses can cause cancer.
These viruses deactivate tumour suppressor proteins meanings cells continuously go through the cell cycle and start proliferating.
Why do we get symptoms when we have an infection?
We get symptoms because the body overreacts to microorganisms.
What is a latent infection?
This is where there is microorganism presence but it is not sufficient to cause symptoms.
Why do recurrent infections occur?
There are always microorganisms present in the body, and their numbers reduce sufficiently that there are no symptoms but then they multiply and it becomes a symptomatic infection once again.
Give an example of a gram negative cocci bacterium.
Neisseria
How can staphylococcus and streptococcus both be classified? (How do they respond to gram staining?)
Gram positive cocci
Classify the bacterium: Clostridium
Bacilli, gram negative.
Give examples of gram positive bacilli bacteria
Salmonella, pseudomonas, legionella, helicobater, escherichia.
Classify papilloma viruses.
They are non enveloped DNA viruses.
Give three examples of an enveloped DNA virus
Hepatitis B, herpes, small pox
Give examples of an enveloped RNA virus
Rubella, HIV, rotavirus, corona virus.
What is an endogenous infection?
Where infection occurs by a pathogen which is found in a persons normal microbiota.
