Microbiology - Systematic Bacteriology Flashcards
In microscopy how can you identify organisms?
Shape, size, grouping
Structures e.g. flagella/spores
Staining e.g. Gram, Ziehl Neelson
What are the 3 most common shapes of bacteria?
Cocci (spheres), Bacilli (rods) and spiral-shaped.
How do cocci bacteria divide?
They divide in one plane or 3, meaning they arrange themselves in chains or clumps.
What is an example of a cocci bacteria which divides in one plane?
Diplococcus.
What is an example of a cocci bacteria which divides in 3 planes?
Staphylococcus.
How do bacilli bacteria join together?
They arrange themselves in chains too and usually have a gram +ve cell wall.
What other shape can bacilli bacteria have?
Slightly curved rod and often Gm -ve wall.
What are the 2 types of spiral shaped bacterium?
Rigid e.g. spirillum and flexible e.g. spirochaete.
What is a spore?
A dormant form of the microogranism.
How is a spore formed?
Binary fission and then sporulation creating a prespore. Through cell lysis a spore is made which is a small compact package and dehydrated to make it resistant.
If it is a Gram +ve, what colour will it be?
Purple.
If it is a Gram -ve what colour will it be?
Pink.
What is the Gram stain?
Simple method that distinguishes classes of bacteria according to cell wall structure.
What is a limitation of Gm Stain?
Not all organisms strain well with Gram stain e.g. TB
What is an obligate aerobe?
They require oxygen.
What is an obligate anaerobe?
Killed by oxygen.
What is a facultative anaerobe?
They tolerate oxygen.
Why is there selective media?
As the presence of specific substances permits the growth of one organism over another.
What does CBA stand for?
Cooked blood agar.
Why is there differential media?
It incorporates chemicals which produce visible change colonies that facilitate identification.
What is heamolysis?
The destruction or rupture of RBC.
In alpha heamolysis what happens?
Greening of the colonies.
In beta heamolysis what happens?
Destruction of the RBC.
In gamma heamolysis what happens?
No heamolysis
What does biochemical characterisation allow?
Metabolic profiling of utilisation of C sources and amino acids.
What does serological tests allow?
Confirm the presences of specific organisms by a specific molecule.
What is agglutination?
the process that occurs if an antigen is mixed with its corresponding antibody.
What does Real Time PCR allow?
May indicate the presence of an organism or even specific virulence factor.
What does MLST stand for?
Multi Locus Sequence Typing.
What does MLST enable?
More knowledge about the evolution of bacteria.
What does MALDI-TOF stand for?
Matrix Assisted Laser Desorption Ionisation Time-Of-Flight.
What does MALDI-TOF do?
Fragments from proteins to the charged screen with positive and negative ends.
Strength and number of times gives a reading of pattern of composition and quantity.
How does MALDI-TOF work?
Generates a series of ions from a sample, separates the ions according to mass and charge, it then detects the spectrum of proteins released from the sample and results in a characteristic signature.
