Flashcards in Microbiology Deck (184)
Organism that causes or is capable of causing a disease.
Organism that colonises the host without causing a disease, in normal circumstances.
List 5 locations commensals are found.
3) mucosal surfaces
List 7 locations commensals are not found, i.e. sterile.
2) cerebrospinal fluid
3) pleural cavity
4) peritoneal cavity
5) lower respiratory tract
6) urinary tract
The degree to which a pathogen is pathogenic.
What is a synonym of virulence?
Define virulence factor. (5)
Molecules produced by pathogens that enable them to:
1) colonise host
2) obtain host nutrients
5) enter and exit cells (intracellular pathogen)
Define asymptomatic carriage.
Pathogen in a tissue site without causing a disease.
List Koch’s postulates of disease. (4)
1) microbe must be found in all diseased individuals
2) microbe must be isolated from diseased individual and grown into a pure culture
3) individual inoculated with pure microbe culture should develop disease
4) microbe must be reisolated from inoculated diseased individual
Paired round bacteria.
Curved rod-shaped bacteria.
Spiral rod-shaped bacteria
Dormant form of bacteria that is highly resistive to physical and chemical influences.
Define opportunistic pathogen.
Organism that causes disease only in immunocompromised individuals.
A state of extreme dryness.
What temperature is the bacterial environment?
-80C to +80C.
What pH is the bacterial environment?
pH 4 to pH 9.
List 3 forms of mutation that lead to genetic variations in bacteria.
List 3 forms of gene transfer that lead to genetic variation in bacteria.
1) transformation, e.g. plasmid
2) transduction, e.g. phage
3) conjugation, e.g. sex pilus
How long can spores be desiccated?
How long can bacteria be desiccated?
2 hours to 3 months.
Lipopolysaccharide (LPS), found on outer membrame of Gram negative bacteria.
Proteins secreted by bacteria.
Which has a specific action, exotoxin or endotoxin?
List the 3 components of LPS of Gram negative bacteria.
1) lipid A - toxic
2) core antigen (R) - short sugar chain
3) somatic antigen (O) - repeating oligosaccharide chain
Which is stable in high temperatures, exotoxin or endotoxin?
What is Gram staining?
Staining method used to separate bacteria into two groups, Gram positive and Gram negative.