Microbiology Flashcards
Explain the characteristics of a eukaryote?
- complex
- multi-cellular
- linear chromosomes
- no cell wall
Explain the characteristics of a prokaryote?
- simple
- circular plasmids
- rigid cell wall
Gram +ve cell wall is usually_________-
- thicker Peptidoglycon
- 1 layer of phopholipids
Gram -ve cell wall is usually___________
- thinner Peptidoglycon
- 2 layers of phospholipids
What colour does gram positive stain
- purple
What colour does gram negative stain?
- pink
Gram positive usually have pilus or fimbriae?
- fimbriae
Gram negative usually have pilus or fimbriae?
- pilus
What is the role of fimbriae and pilus
- fimbriae increases surface area
- adherence and sex
How do prokaryotes grow?
- by binary fission
What are some factors that effect the rate of growth in prokaryotes?
- food
- temperature
- oxygen concentration
- pH
What are the four stages of a prokaryotic life?
- lag
- log
- stationary
- decline
Exotoxins are usually produced by gram___ bacteria?
- positive
Endotoxins are usually produced by gram___ bacteria?
- negative
Shape of cocci?
- spheres
- clusters or chains
Shape of bacilli?
- rods
What are spores?
- inert structures
- resistant to physical and chemical challenge
What is an example of an organism that doesnt stain with gram staining?
- TB
Define aerobic?
- grows in oxygen
Define obligate aerobes
- requires oxygen
Define obligate anerobes
- killed by oxygen
Define facultative anerobes
- tolerated oxygen
What is a selective media?
- a media that selects for the growth of one organism over another
What is a differential media?
- incorporation of different chemicals to produce visible changes
- allows identification
How can you test streptococcus?
- haemolysis test
Alpha haemolysis looks like what? and suggests what?
- partial haemolysis
- strep pneumonia
- strep virdians
Beta haemolysis looks like what? and suggests what?
- complete haemolysis
- strep A or B
What is a serological test?
- immune response test
- detects IgM
Agglutination test
- type of serological test
- detects antibodies associated with agglutination (immune complex formation)
Define virulence
- the capacity of a microbe to cause damage to the host
Define commensal
- part of the normal gut flora
Define pathogen
- harmful organism which produces a pathology
Name some examples of fungal infections
- candida spp.
- yeast
- mould
Name some examples of gram postivie pathogens
- stapholycoccus
- strephtococcus
- enterococcus
- clostridium
Name some examples of gram negative pathogens
- neisseria
- escherichia
- klebsiella
- eneterobacter
What is a coliform?
- gram negative bacilli
- look like E.coli
- part of normal bowel flora
- can cause UTIs
First line antibiotic for a coliform?
- gentamicin
Explain fever production
- antigen binds to macrophage
- macrophage releases cytokines
- cytokines travel to anterior hypothalamus
- prostaglandin E released
- causes a reset in body thermostat
- fever production
Explain sepsis?
- small blood vessels become leaky
- loss in blood volume
- heart rate increases
- poor oxygen perfusion of organs -> shut down
- clotting factors activated
What test can be used to determin between different streptococcu?
- haemolysis test
- Alpha haemolysis suggests?
- strep viridians
- Beta haemolysis suggests?
- complete haemolysis
- strep A or B
Streptococcus would look like what down the microscope?
- cocci chains
What would staphlococcus look like down the microscope?
- cocci clusters
What test is used to distinguish between staphloccus?
- coagulase test
What is a clostridiodes?
- gram positive anaerobic bacilli
- produce spores
- produce exotoxins
Explain the components of a virus?
- nucleic acid
- protein coat
- envelope
- may have protein spikes
Do viruses have RNA or DNA?
- they can have either
- they never have both due to their limitations in size
Explain virus attachment?
- virus spikes antigen to human cell
- ligand and receptor binding
Explain entry of a virus into a human cell
- endocytosis
- viral enzymes
Explain uncoating of a virus
- viral nucleic acids released from virus
- ## may be due to viral ion pump
How do antivirals work?
- may inhibit the viral ion pump responsible for uncoating
- affect viral nucleic acid synthase
Explain assembly of viruses?
- nucleic acids and proteins packaged together
Explain release of viruses?
- budding (host membrane covers, to try and be undetected by immune system)
- lysis (accumulate until the cell is lysed)
What are the 6 stages of virus attack on a human cell?
- attachment
- entry
- uncoating
- protein/nucleic acid synthase
- assembly
- release
Why would someone have no symptoms of a virus but may be infected?
- covalescent phase of disease
- late stage of incubation
- asymptomatic
How can natural resistance to antibiotics rise?
- target not present
- target not accessible
- development of structures (spores)
- metabolism
Define biofilms
- organisms resistant to antimicrobial agents and host defences
How do mutations lead to resistance?
- rapid bacterial growth
- room for error
- mutation rare strains may be more successful
What are the 3 forms of horizontal gene transfer?
- bacterial transduction
- bacterial transformation
- bacterial conjugation
Describe bacterial transformation
- release of DNA
Describe bacterial transduction
- use of phage
Describe bacterial conjugation
- sex pilli
What is the chain of infection
- infectious microbe
- reservoir
- portal of exit
- transmisson
- portal of entry
- susceptible host
Why is the chain of infection important to remeber?
- breaking the chain at any point interrupts transmisson
Name the 5 ways in which infection is spread
- inhalation
- ingestion
- inoculation
- mother to infant
- intercourse
5 moments of hand hygiene?
- before patient contact
- before ascetic procedures
- after exposure to body fluids
- after patient contact
- after contact with patient surroundings
Explain b-lactamases
- enzymes produced by bacteria that provide multi-resistance to b-lactam antibiotics
