Glossary of MB II
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- 5 types of microscopes
- Purpose of Darkfield microscope
- to allow the viewing of bacteria that don't take stains well like spirochaetal.
-light shone from angle bends off bacteria to make a dark background the bacteria show white/light against it.
- phase-contrast microscopy
- take avtg of varying slide densities.
enhances varying wavelengths via PHASE PLATE
specimen appears dark
- what color is
- flourescence microscopy
- certain material emits energy detectable as visible light when irradiated with UV light.
Emission filter sorts out lower energy emitted light.
bacteria stain with flouresc. dye
- are most bacterial stains positive or negative?
- positive, because bacteria have a net negative charge.
- principle of differential stain
- allows to differentiate between groups of bacteria on basis of some property, usually the cell wall.
uses a primary dye and a counterstain.
- negative stains - what for
- to see particular characteristic that won't stain with a positive stain.
CAPSULES are only visible with neg.
- capsule stain
- india ink stains background so bacteria shows up as transparent
- electron microscope
- specimen scatters electrons based on its varying densities.
used in virology, but not very useful cuz we have better techniques.
- 2 major components of outer layer of bacterial cell
- 1. Glycocalyx
2. Cell wall
- glycocalyx - what is it, why?
- -the outermost layer of bacteria.
-made of polysaccharides or polypeptides
-if compact/thick = capsule
-if loosely arranged = slime layer
to protect bacteria from phagocytosis
-allows it to adhere to tissue in host.
- cell wall - where, why?
- Just inside bacterial glycocalyx
-To protect bacteria, maintain rigidity.
Different in Gram + and -
- Layers in Gram + cell wall
- 1. peptidoglycan = 90%
2. teichoic acid/lipoteichoic acid = 10%
- which has more layers, gram + or -
- negative! thinner than positive though
- 3 layers of neg cell wall
- 1. outer membrane - made of lipopolysaccharides, lipoprotein, and porin proteins.
3. periplasmic space
- 2 cell inclusions
- purpose of granule cell inclusions
- store food, they're visible when stained
- purpose of sporulation
- survival mechanism in adverse environmental conditions like dehydration, temperature extremes, or uv light
- Steps of Sporulation
- 1. DNA copied
2. Invaginate cell membrane btwn 2 DNAs
3. Forespore - early coat around nucleic acid.
4. Cell wall forms
5. Cell coat forms - resistant to adverse conditions, also STAIN so we see a hole.
- Only 2 genera that produce spores:
- Aerobic Bacillus and
both are gram positive
- difference between sporogenesis and germination
- sporogenesis is the forming of a spore
germination is the spore going into a vegetative state.
- the four amino acids in a glycan tetrapeptide
lysine or diaminopimelic acid
- peptidoglycan structure
- parallel diagonal lines of alternating G/M/G/M;
M=n-acetyl muramic acid
M's are linked vai glycan tetrapeptide;
- 4 types of classification of Flagella
- Peritrichous - lots around
Monotrichous - one flagell.
Lophotrichous - LUMP of flag.
Amphitrichous - single flagellum at both poles!
Polar - number or singular
- a bacterium that was originally a prototroph and now has developed a specific growth requirement for its media.
- salt-loving bacteria - give it to its media
- media enrichers
- -Growth factors (blood, carbs, NaCl, Vitamins, Amino acids
- enrichment media
- suppresses normal flora while enhancing pathogen growth
- enrichment vs. enriched media
- enrichment enhances all bacterial growth
enriched only enhances growth of bacteria we want to see, not normal flora
- 3 components of gram negative outer membrane
- -lipopolysaccharides (LPS)
-lipoproteins (anchor outer cell membrane)
-porin protein - gets nutrients/proteins into the negative wall
- what is contained in the periplasmic space, what type of organism has it?
- gram negative
contains enzymes for nutrient breakdown
- what is a mesosome?
- an extension of the cell membrane; it increases the surface area of the membrane for increased uptake of nutrients.
- whats in bacterial cytoplasm?
- 3 things:
-chromatin - throughout the cell, no nucleus.
-ribosomes - for protein synthesis.
-granules - for food storage.
- 3 possible shapes of bacteria
- 3 structural componnts of flagella
-type of motion
- a. filament
c. basal body
- important info if organism is ACID FAST:
-not whether its pathogenic or not, but at least you know its mycobac.
- seen in mycobacterium, when the acid fast organisms don't take up the stain evenly.
- when mycobacteria grow with cells lying end to end.
- q.c. on acid fast stain?
- 2 organisms: red bacilli and blue cocci. so mycobacterium and staph aureus.
- chemical component of mycobacterium that makes them acid-fast and resistant to decolorizing:
- -Mycolic acid - waxy lipid, 60% of wall.
- 3 types of cell-wall deficient bacteria:
- a. L-forms
- Lister-forms of bacteria - really are normal but their cell walls have been lost due to high penicillin doses, or high salt. Removing such conditions returns the cell wall to normal.
- Protoplasts vs. spheroplasts
- L-forms of Gram positive, and L-forms of Gram negative.
- special bacteria that does not have a cell wall. Responsible for walking pneumoniae.
- 2ndary pathogens
- cause a disease because a primary pathogen made the host weak
- opportunistic pathogens
- cause a disease because another disease or condition (not necessarily pathogen) made the host weak.
- nosocomial pathogens
- hospital pathogens. often resist antibioitics.
- communicable vs. contagious
- Anthrax is communicable from animals to humans, but not contagious between humans.
- it can be given directly to a person
it can be carried by a person
- components of a chain of infection:
- Type of disease
Effect on host
- 3 possible sites of infection
- -localized (at point of entry)
-focal (extends beyond entry point)
-systemic (carried by blood/lymph)
- 5 types of infection
-subacute (may not know have it)
insidious (very slow)
asymptomatic (subclin, inapparent, carrier)
-latent - viruses are this.
- 4 stages of infection
- incubation - entry, incubate, then symptoms.
prodrome - time betwn incub/no symptoms and symptoms of disease - impending doom
disease - fastigium is peak of symptoms.
convalescence - fewer/milder symptoms, getting better.
- sometimes worse than the initial infection, the post-infection infection.
- port of exit
- same as port of entry; gi tract, respiratory, skin, mucosa, etc.
- Infection meets Koch's postulates if:
- -present in every animal with disease, not in healthy animals.
-microorg can be grown in pure culture in lab from an animal specimen.
-can inoculate healthy animal with cultured isolate and see disease.
-can isolate microorg from 2nd animal and grow in lab for identical result to original isolate.
- 8 steps to identify agent causing infection
- 1. Collect specimen
2. Direct tests
3. Inoculate media
5. Observe macro morpho
6. Observe micro morpho
7. ID tests
8. Antibiotic susceptibility tests
- types of specimen collection
- saliva, sputum, blood, clean catch, catheter, vaginal swab/stick
- 3 types of direct specimen tests
- direct smear - gram stain it
immunological tests - for spcfc Ag.
direct molecular tests - nucleic acid
- 4 types ID tests in lab
- 1. Biochemical - media has tests in it
2. Immunological - detect antigens
4. Serological -detect antibody in serum
4. Molecular -detect unique nucleic acid
- 3 methods of indirect transmission of a pathogen
- -Fomite (inanimate object)
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