Microbiology Midterm Cram

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25 terms

Biosafety level BSL #1

Not known to cause disease

Biosafety level BSL #2

Associated with human disease (contact)

Biosafety level BSL #3

Aerosol transmission/serious or lethal, need ventilation

Biosafety level BSL #4

Aerosol transmission/high risk, need isolation

Antoni van Leewenhoek

Simple microscope

Ernst Abbe

Resolution dependent on lens; used substage/Abbe condenser and iris diaphragm + immersion oil

Immersion oil

Has same refractive index as glass; raises the eta (refractive index) to 1.5, and gives light a medium to travel at constant speed

Total magnification

Objective mag x ocular mag = total mag

Spherical aberration

Fuzzy periphery (Curved lens = multiple focal points)

Chromatic aberration

Multitude of colors (Different wavelengths = multiple focal points)

Numerical Aperture

NA = nsinθ

n = refractive index
θ = 1/2 angle of light

Resolving Power

RP = λ / 2 x NA

wavelength in nanometers (limiting)

When you raise NA, you raise RP, and limit of resolution decreases

CFU

colony forming unit

Basic stains (Simple stain)

Primary stain: methylene blue
Decolorizer: Water
No counterstain

Auxochrome is attracted to negative charges of the bacterial cell surface. The auxochrome becomes positively charged as a result of picking up a hydrogen or losing a hydroxide.

Gram stain

Primary stain: Crystal violet
Mordant: Iodine
Decolorizer: Acid Alcohol
Counterstain: Safranin

Purple: gram positive
Pink: gram negative

Acid Fast

Ziehl-Neelsen

Primary stain: Carbolfuchsin
Decolorizer: Acid Alcohol
Counterstain: Methylene Blue

AF Positive: Pink
AF Negative: Blue

Capsule stain

Primary stain: Congo red (nigrosin)
Maneval's Stain
Water

Spore Stain

Primary stain: malachite green
Decolorizer: water
Counterstain: Safranin

Central, terminal, or subterminal
Can be spherical or elliptical

Flagella stain

Monotrichious: single flagellum on one end
Amphitrichious: both ends

Lophotrichious: tufts at end
Peritrichious: entire surface (Proteus vulgaris)

Columbia CNA with 5% Sheep Blood Agar

Selective agents: Colistin, Nalidixic Acid (CNA)
Indicators: red blood cells

Hemolysis (beta, alpha, or gamma) determines Gram positive; gram negative inhibited by colistin and does not grow

Bile Esculin Azide Agar

Selective agents: sodium azide, bile
Indicators: Ferric citrate

Darkening = Streptococcus Group D, Enterococcus

Mannitol Salt Agar

Selective agents: sodium chloride, mannitol
Indicators: phenol red

Mannitol fermentation + yellow halo: Staphylococcus aureus

MacConkey Agar

Selective agents: Bile salts and crystal violet
Indicators: Lactose w/ red dye

Growth = gram negative
Red fermentation = coliform

Eosin Methylene Blue Agar

Selective agents: lactose and sucrose, eosin Y + methylene blue
Indicators: Dye (Eosin Y + methylene blue)

Growth = gram negative
Pink + mucoid: possible coliform
Dark: probable coliform
No color: non coliform gram negative

Hektoen Enteric Agar

Selective agents: bile salts, Hektoen enteric agar
Indicators: lactose + sucrose, sodium thiosulfide

Salmonella reduces sulfur to hydrogen sulfide and forms a black precipitate

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