25 terms

Microbiology Midterm Cram

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
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

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
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