Microbio Lab Practical

Question 1

Endospore stain

Answer 1

Pink w/ green dots (spores are green)
Stains: malachite green and safranin
Steam on beaker

Question 2

Capsule stain

Answer 2

Purple background & purple bacteria and white rings (capsules)
Stain: congo red, maneval’s
DO NOT HEAT FIX

Question 3

Negative staining

Answer 3

Background is stained black
Stain: negrosin

Question 4

Simple staining

Answer 4

Bacteria is stained
Stain: Crystal violet

Question 5

Acid fast staining

Answer 5

Stains: carbofushin and methylene blue

Question 6

Gram staining

Answer 6

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

Question 7

Citrate test

Answer 7

Positive result - blue
Negative result - green
Tests for citrate utilization
No reagent required
Media: Simmons citrate slant

Question 8

Glucose and Lactose Fermentation tests

Answer 8

Tests acid and gas
Gas positive is bubble in Durham tube
Acid negative is pink
Acid positive is yellow
No reagent
Media fermentation tube

Question 9

MRVP Test (MR)

Answer 9

Tests for mixed acid fermentation pathways
Positive - pink
Negative- yellow
Reagent is methyl red
Media: MRVP Broth

Question 10

MRVP Test (VP)

Answer 10

Tests for neutral end products
Positive: cleanish yellow
Negative: foam on top
Reagent: VP ampoules A & B
Media: MRVP broth

Question 11

Nitrate reduction test

Answer 11

Durham tube bubble is positive
Negative: light red
Positive: dark red (nitrite) or clear (anything else)
Reagent: nitrate A & B
Media: nitrate broth

Question 12

Oxidase test

Answer 12

Tests for production of oxidase
Positive: change to purple
Negative: no color change
Reagents: oxidase ampoule
Media TSA plate

Question 13

Catalase Test

Answer 13

Tests for catalase production
Positive: bubbles
Negative: no bubbles
Reagent: 3% hydrogen peroxide
Media: TSA plate

Question 14

Hydrolytic test

Answer 14

Tests for starch
Positive: clear zone
Negative: purple/black
Reagent: Gram’s iodine
Media Starch Agar plate

Question 15

Indole Test

Answer 15

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

Question 16

Urea Test

Answer 16

Tests for urease production
Positive: pink
Negative: no color change
No reagent
Media: urea broth

Question 17

Phenylalanine Test

Answer 17

Tests for phenylalanine deaminase
Positive: green
Negative: yellow
Reagent: ferric chloride
Media: phenylalanine slant

Question 18

SIM (sulfur indole motility) test

Answer 18

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

Question 19

Disinfectants

Answer 19

Reduce microbes for inanimate objects

Question 20

Antiseptics

Answer 20

Reduce microbes for living tissue

Question 21

Sterilize

Answer 21

No microbes present
Heat, radiation, and filtration

Question 22

Disk diffusion assay

Answer 22

Different disinfectants and antiseptics applied to determine zone of inhibition on a microbe. Larger zone = more effective. selective media agar

Question 23

Epidemiology

Answer 23

How epidemic are spread.

Question 24

Common source epidemic

Answer 24

People get sick all from the same source
(Eating the same food at a restaurant)

Question 25

Propagated Epidemic

Answer 25

Starts with one person and spreads to others (the flu)

Question 26

Communicable Disease

Answer 26

Contagious disease (can cause propagated epidemic)

Question 27

Index Case

Answer 27

First case in propagated epidemic

Question 28

Epidemiology triangle

Answer 28

Pathogen - environment - host (in a love triangle)

Question 29

Chain of transmission

Answer 29

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

Question 30

PCR (Polymerase Chain Reaction)

Answer 30

Amplify DNA samples to produce multiple copies

Question 31

3 Steps of PCR Cycle and appropriate temperatures

Answer 31

Denature (95°C), Annealing (50-60°C), and Extension (72°C)

Question 32

T/F Herd immunity is the percent of individuals in a population immune to a disease, and it is increased significantly through vaccination

Answer 32

True

Question 33

T/F The first case of a propagated epidemic is called the primary case and each new case is a secondary case

Answer 33

False (first case is called index case)

Question 34

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

Answer 34

Selective; differential

Question 35

Selective media

Answer 35

One 1 type of bacteria will grow on it

Question 36

Differential media

Answer 36

Allow dissimilar to be distinguished from each other based on their physical appearance or colony morphology

Question 37

Reduced media

Answer 37

A type of media used to cultivate obligate anaerobes

Question 38

Fives I’s of microbiology

Answer 38

1) inoculation 2) isolation 3) incubation 4) inspection 5) identification

Question 39

Plate used to isolate gram negative bacteria

Answer 39

MacConkey Eosin Methylene Blue Hektoen Agar