Unit 8: Microorganisms

What is a prokaryote?

cell whose genetic material is not enclosed in a nuclear envelope

What cell walls do bacteria have?

peptidoglycan

What shape do bacilli have?

rod

What uses two or more dyes and distinguishes various parts/properties of organisms and tissue?

differential stain

When was the Gram stain developed?

1884

Gram-positive cells have a __ peptidoglycan layer.

thick

Gram-negative cells have a __ peptidoglycan layer.

thin

Which type of cell contains teichoic acids? gram-positive cell or gram-negative cell

gram-positive cell

Which type of cell stains with primary stain? gram-positive cell or gram-negative cell

gram-positive cell

Which type of cell has a layer of lipo-polysaccharide? gram-positive cell or gram-negative cell

gram-negative cell

Which type of cell stains with counterstain? gram-positive cell or gram-negative cell

gram-negative cell

Is Staphylococcus aureus a gram-positive cell or gram-negative cell?

gram-positive cell

Is Streptococcus pneumoniae a gram-positive cell or gram-negative cell?

gram-positive cell

Is Clostridium spp. a gram-positive cell or gram-negative cell?

gram-positive cell

Is Shigella dysenteriae a gram-positive cell or gram-negative cell?

gram-negative cell

Is Escherichia coli a gram-positive cell or gram-negative cell?

gram-negative cell

Is Salmonella spp. a gram-positive cell or gram-negative cell?

gram-negative cell

Is Pseudomonas aeruginosa a gram-positive cell or gram-negative cell?

gram-negative cell

Is Neisseria spp. a gram-positive cell or gram-negative cell?

gram-negative cell

First step of Gram stain?

Application of crystal violet (purple dye)

Second step of Gram stain?

Application of iodine (mordant)

Third step of Gram stain?

Alcohol wash (decolorization/differentiation)

Fourth step of Gram stain?

Application of safranin (counterstain)

Acid fast stains are based on the properties of the ___

cell wall

Is acid fast stain a progressive or regressive stain?

regressive

Acid fast organisms have a __ layer of peptidoglycan.

thin

Acid fast is gram positive. t or f?

true

What type of organism is Mycobacterium tuberculosis?

acid-fast

What type of organism is Mycobacterium leprae?

acid-fast

What type of organism is Nocardia spp.?

acid-fast

Acid-fast organisms have a thick layer of __

mycolic acids

Are spiral organisms gram positive or gram negative?

gram-negative cell

What is best demonstrated with silver stains?

spirochetes

What is Treponema pallidum?

spirochete

What is Borrelia burgdorferi?

spirochete

What is Rickettsiae?

atypical bacteria

What is Chlamydiae?

atypical bacteria

What is Mycoplasma?

atypical bacteria

T or F, fungi is prokaryotic.

false

Fungi cell wall is composed of…

chitin

What is mycology?

study of fungus

What is mycosis?

fungal disease

T or F, chitin is a carbohydrate.

true

Yeast reproduce by…

budding

What is Cryptococcus neoformans?

yeast

Yeast reproduces by budding, but forms..

pseudohyphae

What is Candida albicans?

yeast

What is also called filamentous fungi?

molds

Molds contain and __ .

hyphae, mycelium

What is dimorphic fungi?

Fungi that have two types of growth: filamentous, yeast-like

What temperature is filamentous?

25°C

What temperature is yeast-like?

37°C

What is Histoplasma capsulatum?

dimorphic fungi

What is Coccidioides immitis?

dimorphic fungi

What is Pneumocystis jiroveci?

fungi

What is rabies?

Virus (Negri bodies)

What does cytomegalovirus have?

acidophilic inclusion bodies

What is Giardia lamblia?

virus

What is Entamoeba histolytica?

virus

What is Toxoplasma gondii?

virus

What does Brown-Hopps demonstrate?

gram-positive cell, gram-negative cell

What fixative to avoid with Brown-Hopps?

Bouin solution

What’s the primary stain in Brown-Hopps?

Crystal violet

What’s the secondary stain in Brown-Hopps?

Basic fuchsin

What’s stains tissue/counterstain for background in Brown-Hopps?

Picric acid-Acetone

Nuclei has an affinity for __ so it doesn’t decolorize in Gram stains.

Basic fuchsin

What stain is used to demonstrate bacteria, rickettsias, and Toxoplasma gondii?

Giemsa stain

Preferred fixative for Giemsa stain when used for hematopoietic tissue?

zinc

Preferred fixative for Giemsa stain when used for microorganisms?

10% NBF

T or F, Giemsa is a Romanowsky stain

true

What color is bacteria stained in Giemsa stain?

blue

Which stain is used to demonstrate H. pylori?

Modified Diff-Quik

Cytoplasm is what color in Modified Diff-Quik?

pink

H. pylori and nuclei stains what color in Modified Diff-Quik?

dark blue

Bacteria stains what color in Modified Diff-Quik?

blue

What dye is specific for mycobacteria?

Carbol-fuchsin

What reagent gives more uniform results, for acid-fast stains?

Alcoholic acid

T or F, carbol-fuchsin is less soluble in the lipid of the cell wall than in acid-alcohol.

false

What fixative to avoid for acid-fast stains?

Carnoy solution

What reagent in Carnoy solution causes it to not be used for acid-fast stains?

chloroform

T or F, Kinyoun has heat.

false

T or F, Ziehl-Neelsen has heat.

true

T or F, Kinyoun has a higher concentration of basic fuchsin and phenol than Ziehl-Neelsen.

true

T or F, Ziehl-Neelsen has a higher concentration of basic fuchsin and phenol than Kinyoun.

false

To avoid a compound that is resistant to decolorization, do not allow slides to __ after carbol-fuchsin.

dry

What color is acid-fast bacteria stained?

bright red

Fite Acid-Fast stain is used to demonstrate…

Mycobacterium leprae

What stain is used for Mycobacterium leprae?

Fite acid-fast

What is the capsule of M. leprae sensitive to?

alcohols, xylenes

For Fite acid-fast stain, tissues are deparaffinized in…

peanut oil/xylene

For Fite acid-fast stain, do not coverslip with..

alcohols, xylenes

Nocardia spp is weakly __

acid-fast

What is the fluorescent stain for acid-fast bacteria?

Auramine-Rhodamine fluorescence

What stain is to detect M. tuberculosis and other acid-fast organisms?

Auramine-Rhodamine fluorescence

What fixatives to avoid for Auramine-Rhodamine fluorescence?

heavy metal

Auramine-Rhodamine fluorescence technique selectively stains mycobacteria by binding dye to the ____ of the cell wall.

mycolic acid

Hotchkiss-McManus PAS reaction demonstrates..

fungi

What fixative to avoid with Hotchkiss-McManus PAS reaction?

glutaraldehyde

Which stain is this: Polysaccharides in fungal cell wall oxidized to aldehydes by the periodic acid

Hotchkiss-McManus PAS reaction

In Hotchkiss-McManus PAS reaction, the aldehydes react with…

Schiff reagent