Bacterial anatomy Flashcards
Shape of diplococci, streptococci, staphylococci?
2 associated cocci
chains of cocci
clusters of cocci
What general type of bacteria are spherical?
-cocci
What is a sarcinae?
Pack of 8 cocci arising from alternating cell division planes
What general bacteria are rod shaped?
Bacilli
Fusiform shape? Type?
Tapered end
Bacilli
Clavate/coryneform shape? Type?
Club shaped
Bacilli
Filamentous shape? Type?
Filamentous
Bacilli
Vibrios shape? Type?
Comma shaped
Bacilli
Spirilla shape? Type?
Snake-like
Bacilli
Coccobacilli shape? Type?
Ovoid or ellipsoid
It is its own type
Spirochetes shape?
Flexible envelopes and corkscrew appearance
It is its own type
What are intracytoplasmic granules?
Inclusion bodies or metachromatic granules for storage of energy polymers (glycogen)
What determines if a bacterium is gram + or - ?
Thickness of the cell wall, which is visualized with a gram stain
How do you perform a gram stain?
- stain with crystal violet (purple) and iodine
- destain with acetone and ethanol
- counterstain with safranin (red)
What colors do they bacteria turn with a gram stain?
gram + purple
gram - red
3 examples of gram + bacteria? Shapes?
Staphylococcus aureus (clusters of spheres) Streptococcus pneumonia (chain of spheres) Clostridium botulinum
Cytoplasmic membrane of gram + bacteria: do they contain sterols?
No (unlike eukaryotes)
Cytoplasmic membrane of gram + bacteria: do they have integral membrane proteins?
Yes (like eukaryotes)
Gram + bacteria cell wall is important for which response?
Inflammatory response
What makes up gram + cell wall? How many layers?
Peptidoglycans
40 layers
Peptidoglycan synthesis is a target of what?
Antibiotics
What are lipoteichoic acids? Toxic?
They promote negative surface charge (similar to lipopolysaccharides in gram - bacteria)
They are present in all gram + bacteria
They are nontoxic but contribute to virulence
3 examples of gram - bacteria? Shapes?
Neisseria gonorrhea - rods
Escherichia coli - rods
Salmonella typhimurium
Cytoplasmic membrane and cell wall of gram - bacteria?
Cytoplasmic membrane is similar to that of gram +
Cell wall is only 1 layer thick, which is why it doesn’t retain the gram stain
What is the periplasmic space in gram - bacteria?
It is between the inner and outer membranes
It contains a peptidoglycan layer and hydrolytic enzymes
It also contains detoxifying enzymes (beta-lactamase inactivates penicillin)
Is the outer membrane of gram - bacteria different from the cytoplasmic membrane? What gets through?
Yes, it is less permeable.
Some polar molecules get through, while others have to go through pores
What accounts for the native bacterial resistance of gram - ?
The antibiotics can’t get through the outer membrane
What molecule, similar to lipoteichoic acid, do gram - outer membranes contain?
lipopolysaccharide (LPS or endotoxin)
Are gram + or gram - bacteria more resistant to antibiotics?
Gram -
What is responsible for the toxicity of lipopolysaccharide (LPS)?
Lipid A can cause endotoxic shock
What are the three major components of lipopolysaccharide (LPS)?
Lipid A
Core oligosaccharide
Repeating or O antigen - contains serologic determinants of endotoxin
Porins are major outer membrane proteins that are _____mers.
A porin mutation can create what?
Trimers
Bacterial resistance can result from a porin mutation.
Pores allow solutes less than ______ Daltons to pass through
~700 Daltons
Mycobacteria are what kind of bacteria? 2 examples?
Acid fast bacteria
Tuberculosis and leprae
Mycobacteria usually stain positively with the gram stain because?
They have a lot of waxes in their cell walls. The waxes are made up of mycolic acids.
The wax prevents the stain from washing out.
Aside from mycolic acid, what 3 things make up mycobacteria?
Murein
Polysaccharides
Lipids
Acid fast stain?
- Stain with carbol-fuchsin (red) and heat
- Destain with 3% HCl and alcohol
- Counterstain with methylene blue
What color do acid fast/gram +/- turn with the acid fast stain?
Acid fast turn red
Gram +/- turn blue
Whats an example of mollicutes, which are cell wall deficient bacteria? Is it easy to stain? Antibiotics?
Mycoplasma, which causes walking pneumonia.
Difficult to stain
Antibiotics won’t work
When gram +/- bacteria lose their peptidoglycan coat, what are they called?
L-form/L-phase
They can be selected for clinically by use of antibiotics
Borrelia and treponema are what types of bacteria?
Spirochetes
Clostridium, listeria, bacillus, corynebacterium are what type of bacteria?
Gram + rods
Staphylococcus and streptococcus are what type of bacteria?
Gram + cocci
Myobacterium are what type of bacteria?
Acid fast
What is a capsule? Gram + or - ?
Polysaccharide coat
Both gram +/-
3 capsule types? Describe.
Slime is weakly adherent
Microcapsule is a thin coat
Biofilm is a growth within layers of polysaccharide, very high resistance that covers the entire colony
How are capsules visualized?
By the exclusion of India ink
What is the Quellung reaction?
Used to serotype bacteria
Do capsules contribute to virulence?
Yes
What 3 factors of capsules help the bacteria avoid host defenses?
Antiphagocytic
Interferes with complement
Growth in a biofilm prevents access of host cells or antibiotics
What are sex pili? They serve as receptors for what?
Facilitate transfer of DNA during conjugation (bt bacteria)
They serve as receptors for bacteriophages
What are fimbriae or somatic pili?
Allow bacteria to adhere to various surfaces
They are important in infection by some bacteria (neisseria gonorrhea)
Flagella are for what?
Movement (counter clockwise movement moves bacteria toward attractants, which is called positive chemotaxis)
Neisseria and moraxella are examples of what bacteria type?
Gram - cocci
What does -trichous describe?
Distribution of flagella
What are virulence factors?
They enhance the ability of the bacterium to cause infection
Loss of virulence factor can make bacteria what? What happens?
Non-pathogenic
Colonization and infection without disease
Carrier state
Can a virulence factor be restored?
Yep, can occur rapidly
