METHODS OF BACTERIAL IDENTIFICATION Flashcards
memorization
Hanging drop technique is a test for:
Motility
Used to detect Treponema pallidum in material from primary or secondary syphilitic lesions or other spirochetes such as Leptospira:
Darkfield microscope
Useful in unstained specimens:
Phase-contrast microscopy
The primary stain of gram stain:
Crystal violet
Duration of primary stain:
1 minute
Mordant of gram stain:
Gram’s iodine
Duration of the mordant:
1 minute
Decolorizer of gram stain:
Alcohol-acetone
Duration of decolorizer in gram stain:
Quick on and rinse
Secondary stain of gram stain:
Safranin
Duration o the secondary stain in gram stain:
30 seconds
Most critical step in gram staining:
Decolorizing
What is the purpose of mordant in gram staining?
Fixes the stain
A unique component in bacteria where Acid-fast stain binds to.
Mycolic acid in the cell wall
Hot method of acid-fast staining:
Ziehl-Neelsen
Cold method of acid-fast staining:
Kinyoun
Primary stain of AFP:
Carbol fuchsin
Mordant used in cold method AFP:
Phenol
Mordant used in Hot method AFP:
Heat
Decolorizer of AFP:
Acid-alcohol
Secondary stain of AFP:
Methylene blue or Malachite green
AFP smear size should be at-least like a thumb size or _____.
2 cm X 3 cm
Used to stain mycobacteria; binds to mycolic acid in the organism’s cell wall, staining the bacteria yellow to orange:
Rhodamine-auramine
Fluorochrome dye that stains both gram-positive and gram-negative bacteria, living or dead; Binds to the nucleic acid of the cell and fluoresces as a bright orange when a fluorescent microscope is used.
Acridine orange
Fluorochrome dye that binds to chitin in fungal cell walls. Fluoresces as a bright apple-green or blue-white, allowing visualization of fungal structures with a fluorescent microscope.
Calcofluor White
Traditionally has been used to stain C. diphtheria for observation of metachromatic granules; Also used as a counterstain in acid-fast staining procedures.
Methylene blue
Metachromatic granules observed in C. diphtheria when stain when stained with methylene blue:
Babes Ernst Granules
Negative stain used to visualize capsules surrounding certain yeasts such as Cryptococcus spp.
India ink
The primary stain of Endospore stain:
Malachite green (heated to steaming for about 5 minutes|)
Counter stain of Endospore stain:
Safranin
Endospores appear _______ within pink-appearing or red-appearing bacterial cells:
Endospores appear GREEN within pink-appearing or red-appearing bacterial cells
Endospore stain is also known as:
Schaeffer-Fulton stain/ Wirtz-Conklin stain
Use fluorescein-labeled antibodies from antisera produced by injecting animals with whole organisms or complex antigen mixtures.
Immunofluorescent antibody (IF) staining
IF staining is most useful in confirming the presence of specific organisms such as _______ or _______ in colonies isolated on culture media.
Bordetella pertussis or
Legionella pneumophilia
Contains no solidifying agent (Broth, Infusion, Milk)
Liquid culture media
Semi-solid culture media contains ____% Agar; Red algae/Gelidium
Semi-solid agar: 0.5-1% Agar
Solid Liquefiable culture media contains _____% Agar
2-3% Agar
Non-liquifiable culture media:
Chopped meat (Anaerobe)
Rice grain (Fungi)
__________ is recommended for organisms that cannot grow in cell-free media.
Tissue cell culture
Mccoy cell culture comes from:
Mouse cell line
Mccoy cell culture is used to isolate:
Chlamydia
Vero cell culture comes from:
African green monkey
A549 cell culture comes from:
Lung carcinoma
Hela cell culture comes from:
Cervical carcinoma
Hep-2 cell culture comes from:
Laryngeal carcinoma
Supports the growth of non-fastidious organisms.
ex: Nutrient agar or broth; trypticase soy agar or broth
Simple/General
Select the growth of a particular organism and prevent other organisms through inhibitors.
Selective media
Lowenstein Jensen media is a selective medium used to isolate:
Mycobacterium tuberculosis
Phenylethyl alcohol media is a selective medium used to isolate:
Gram-positive microorganism
Selective media used to isolate Neisseria gonorrhea
Thayer Martin
Martin Lewis
New york city
Culture media that contains nutrient supplements.
Enriched
Blood agar plate is an enriched culture media that contains:
5% defibrinated Sheep blood (Horse/Rabbit)
Sheep blood is the most preferred!
If human blood is used to make blood agar, what type of blood must be used?
Type O blood
Can enhance the growth of microorganisms
Enrichment media
Alkaline peptone water is an example of an enrichment media that used for:
Vibrio
Allow certain types of organisms to grow and differentiate, and inhibit the growth of other organisms.
Selective-Differential
Mannitol salt agar is a type of selective-differential media that is used for:
S. aureus and S. epidermidis/saprophyticus
- S. aureus forms a yellow halo (red—>yellow) around the colony which indicates mannitol fermentation
- Other Staph spp. can grow but remains red
Thiosulfate Citrate Bile Salt is a type of selective-differential media that is used for:
Vibrio spp.
Provides distinct colonial appearance of microorganisms to know their identification:
Differential media
TSI (Triple Sugar Iron) contains 3 sugars. What are these 3 sugars?
Lactose
Glucose
Sucrose
Green zone around colony. May be narrow or wide; Partial lysis of RBCs.
Alpha hemolysis
Examples of alpha-hemolytic organisms:
- Streptococcus pneumoniae
- Viridans strep
- Some enterococci
Clear zone around colony. May be narrow or wide; Complete lysis of RBCs
Beta-hemolysis
Examples of Beta-hemolytic organisms:
- Group A strep (S. pyogenes)
- Group B strep (S. agalactiae)
- Listeria monocytogenes
No zone of hemolysis; No lysis of RBCs:
Gamma (nonhemolytic)
An organism characterized by its “double zone” hemolysis also known as target hemolysis:
Clostridium perfringens
- C. perfringens causes Gas gangrene
Alpha-prime (a’) or wide zone hemolysis is demonstrated by:
Viridans strep
To read the hemolytic reaction on a blood agar plate, the plate must be held up to a light source and observed with the lighting ______________.
lighting coming from behind (transmitted light)
