Lab diagnosis RED WORDS Flashcards
pure cultures cultivated by?
cultivated and maintained via aseptic technique
Describe aseptic technique
- sterilize loop via flame
- flaming tube tip to sterilize it (after uncapping it)
- only sterilized portion of loop touches tube
- tube tip reflamed
- tube recapped and loop resterilizes
defined medium
chemically defined
complex medium
chemically UNdefined
colonies are isolated how?
Koch developed streak plate method to get visible, isolated masses
What type of media is Eosin Methylene Blue Agar (EMB)
both selective and differential media
What type of media is McConkey’s agar?
*+ or - results mean?
both selective and differential media
- often used to determine if a gastrointestinal microorganism that causes diarrhea is a pathogen
- *lactose negative= pathogen
- *lactose positive= non-pathogen
Blood Agar?
Help ID?
- contains whole blood cells
* useful complex media for isolation and identification of pathogenic Streptococcus pyogenes that causes strep throat
Chocolate Agar
Helps ID what bacteria?
- contains hemolyzed blood
* used for isolation of Neisseria meningitidis
What type of media is Mannitol Salt Agar?
*types of staph found
- selective differential media
- often used to ID suspected Staph food poisoning BC only staph bacteria grows well in the high salt of this media
- -Staphylococcus aureus changes agar to YELLOW and is found in food
- -Staphylococcus epidermis not in food
Broths
have all the necessary nutrients in a liquid form
Agar media
have all the necessary nutrient in a gelled liquid
What makes up Nutrient broth or Nutrient agar?
a non-defined (complex) media
**contains: water, dried beef-extract, peptone (soy beans), with or without agar
Growth factors
specific substances such as Vitamins or Amino acids that are required by certain bacteria
What are auxotrophs?
bacteria that require one or more growth factors
Stains or staining
treatment of organisms with dyes to make them visible under microscopes
- reveals shape, size, internal and external structures
- may produce specific reactions to discriminate microbes
Simple stain
is when a single reagent like methylene blue is used to see gross cellular morphology
•Simple and/or differential cell staining are used to increase contrast in brightfield microscopy.
Differential stain
is when 2 or more stains are used
•Allows classification of bacteria based upon differences in stain uptake
•Simple and/or differential cell staining are used to increase contrast in brightfield microscopy.
Steptococcus mutans is Gram positive or Gram negative?
Gram positive (purple)
Porphyromonas gingivalis is Gram positive or Gram negative?
Gram negative (red)
confocal scanning laser microscopy (CSLM)
is a form of light/fluorescent microscopy that allows for greater threedimensional imaging than other forms of light microscopy
–planes are visualized by adjusting the plane of focus of laser beam
electron microscope
electrons are used instead of light rays
•Electron microscopes have far greater resolving power than light microscopes, with limits of resolution of about 0.2 nm
transmission electron microscope
with thin sectioning the internal structures can be viewed
scanning electron microscope
view the surfaces of microbes by coating with gold
Seroconversion
occurs when antibody is produced in response to a primary infection
Selective Media
a bacterial growth media that allows only certain species or strains of bacteria to grow
-EMB agar only allows gram- bacteria to grow
Differential Media
bacterial media in which certain bacteria that grow on these media take on unique colony characteristics
-EMB agar E. coli colonies have a green sheen
light microscope
ordinary visible light is beamed through a stained microbe
phase contrast
dark image on lighted background- visualize live samples and avoid distortion from cell stains; image contrast is derived from the differential refractive index of cell structures versus background
dark field
lighted image on dark background- Greater resolution can be obtained using dark-field microscopy, in which only the specimen itself is illuminated
most widely used differential stain?
gram stain
*positive (purple) or negative (red)
Acid fast stain differential stain is used to distinguish?
Mycobacterium tuberculosis
-difficult to stain bc mycolic acids present in cell wall
Acid fast bacteria staining procedure? Color they turn?
retain the primary stain upon treatment with acid alcohol •1.Carbolfucsin (red) - primary stain •2.acid alcohol - decolorizer •3.methylene blue - counterstain ---•Acid Fast = Red ---•Non-Acid Fast = Blue
Carbolfucsin (red) in acid fast stain
primary stain
acid alcohol in acid fast stain
decolorizer
methylene blue in acid fast stain
counterstain
•Acid Fast = Red
•Non-Acid Fast = Blue
fluorescence microscope
1) all or parts of a microbe are tagged with a fluorescent molecule
2) the molecule is hit with a wavelength of light that will excite the fluorescent molecule
3) the excited molecule will then fluoresce and can be viewed against a dark background
– oftentimes the fluorescent molecule is attached to an antibody that will recognized a specific type of molecule on the microbe
direct vs indirect fluorescence microscope
- direct assay= antiviral antibody modified with a fluorescent/enzyme probe
- indriect assay= using antiviral antibody and chemically modified anti-immunoglobulin
