Microbio Lab Practical Flashcards
Endospore stain
Pink w/ green dots (spores are green)
Stains: malachite green and safranin
Steam on beaker
Capsule stain
Purple background & purple bacteria and white rings (capsules)
Stain: congo red, maneval’s
DO NOT HEAT FIX
Negative staining
Background is stained black
Stain: negrosin
Simple staining
Bacteria is stained
Stain: Crystal violet
Acid fast staining
Stains: carbofushin and methylene blue
Gram staining
Purple- positive
Pink- negative
60 seconds crystal violet
5 seconds water
30 seconds grams iodine
10 seconds ethanol
10 seconds water
30 seconds safranin
Wash with water
Blot dry
Citrate test
Positive result - blue
Negative result - green
Tests for citrate utilization
No reagent required
Media: Simmons citrate slant
Glucose and Lactose Fermentation tests
Tests acid and gas
Gas positive is bubble in Durham tube
Acid negative is pink
Acid positive is yellow
No reagent
Media fermentation tube
MRVP Test (MR)
Tests for mixed acid fermentation pathways
Positive - pink
Negative- yellow
Reagent is methyl red
Media: MRVP Broth
MRVP Test (VP)
Tests for neutral end products
Positive: cleanish yellow
Negative: foam on top
Reagent: VP ampoules A & B
Media: MRVP broth
Nitrate reduction test
Durham tube bubble is positive
Negative: light red
Positive: dark red (nitrite) or clear (anything else)
Reagent: nitrate A & B
Media: nitrate broth
Oxidase test
Tests for production of oxidase
Positive: change to purple
Negative: no color change
Reagents: oxidase ampoule
Media TSA plate
Catalase Test
Tests for catalase production
Positive: bubbles
Negative: no bubbles
Reagent: 3% hydrogen peroxide
Media: TSA plate
Hydrolytic test
Tests for starch
Positive: clear zone
Negative: purple/black
Reagent: Gram’s iodine
Media Starch Agar plate
Indole Test
Tests for Hydrolysis of tryptophan into Indole
Positive: red ring at top of broth
Negative: yellow ring at top of broth
Reagent: Indole Ampoule (Kovac)
Media: Tryptone broth
Urea Test
Tests for urease production
Positive: pink
Negative: no color change
No reagent
Media: urea broth
Phenylalanine Test
Tests for phenylalanine deaminase
Positive: green
Negative: yellow
Reagent: ferric chloride
Media: phenylalanine slant
SIM (sulfur indole motility) test
Tests for Indole & sulfur production and motility
Positive: red ring (indole), black at bottom (sulfur), bacteria moved (motility)
Negative: nothing happens
Reagent: Indole ampoule (Kovac’s reagent)
Media: SIM deep
Disinfectants
Reduce microbes for inanimate objects
Antiseptics
Reduce microbes for living tissue
Sterilize
No microbes present
Heat, radiation, and filtration
Disk diffusion assay
Different disinfectants and antiseptics applied to determine zone of inhibition on a microbe. Larger zone = more effective. selective media agar
Epidemiology
How epidemic are spread.
Common source epidemic
People get sick all from the same source
(Eating the same food at a restaurant)
Propagated Epidemic
Starts with one person and spreads to others (the flu)
Communicable Disease
Contagious disease (can cause propagated epidemic)
Index Case
First case in propagated epidemic
Epidemiology triangle
Pathogen - environment - host (in a love triangle)
Chain of transmission
Germs
Where germs live (environment)
How germs get out (coughing)
Germs get around
People touch the germs and themselves
They get the germs
People spread germs
PCR (Polymerase Chain Reaction)
Amplify DNA samples to produce multiple copies
3 Steps of PCR Cycle and appropriate temperatures
Denature (95°C), Annealing (50-60°C), and Extension (72°C)
T/F Herd immunity is the percent of individuals in a population immune to a disease, and it is increased significantly through vaccination
True
T/F The first case of a propagated epidemic is called the primary case and each new case is a secondary case
False (first case is called index case)
Because EMB agar inhibits the growth of Gram-Positive bacteria and specific coliform bacteria from distinct colonies when fermenting lactose, it is considered both a ______ and a _____ medium
Selective; differential
Selective media
One 1 type of bacteria will grow on it
Differential media
Allow dissimilar to be distinguished from each other based on their physical appearance or colony morphology
Reduced media
A type of media used to cultivate obligate anaerobes
Fives I’s of microbiology
1) inoculation
2) isolation
3) incubation
4) inspection
5) identification
Plate used to isolate gram negative bacteria
MacConkey
Eosin Methylene Blue
Hektoen Agar
