Microscopic Methods of Examination

Question 1

routinely used for observing microbial cells. gives wider filed of view, less distortion, and less eye strain

Answer 1

Compound microscope

Question 2

• high power objectives, low power objectives and oil immersion
• magnified real image inside the tube of the microscope

Answer 2

Objective lens

Question 3

-lens that are closer to our eyes

Answer 3

ocular lens

Question 4

-combination of the two lens; 100x objective lens , and 10x ocular lens gives a total magnification of 1000x

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Answer 4

Ultimate Magnification

Question 5

put the sample in a proper media

Answer 5

inoculate

Question 6

semi-solid type of culture media

Answer 6

in a Petri Dish

Question 7

liquid or broth type of culture media

Answer 7

in a test tube

Question 8

how to obtain and prepare sample for microscopy (culture and sensitivity)

Answer 8

1. get a sample from the wound
2. prepare a proper transport media (sample media) for the wound and the media will be transported to the laboratory
3. inoculate the sample in a culture media (to cultivate the bacteria)

Question 9

• most common type microscope
• uses light and views the image directly
• used for observing stained cells

Answer 9

Bright field microscopy

Question 10

• the opposite of your bright field microscopy

- used to examine live micro-organisms that either invisible in the ordinary microscope

Answer 10

Darkfield microscopy

Question 11

most common diagnostic use of darkfield microscopy in specific organism

Answer 11

Treponema pallidum (causes syphilis)

Question 12

Advantages of Darkfield Microscopy

Answer 12

• ideal for viewing objects that are unstained
• transparent and absorbs little or no light
• study for marine organisms
• research of live bacterium

Question 13

Disadvantages of DARKFIELD microscopy

Answer 13

-prone to degradation, distortion and inaccuracies

Question 14

phase contrast microscopy

Answer 14

• one of the great advances of microscopy
• most common view under phase contrast is Amoeba, and other parasitic organisms that are too small to be seen under the normal microscope

Question 15

Fluorescence microscopy

Answer 15

-very complex instruments

Question 16

Electron microscopy

Answer 16

• one of the highest form of microscope in the field
• uses electromagnetic lenses to bend a beam of electrons
• the resolution of the electron microscope is a thousand-fold better than the light microscope
• specimen needs to be dehydrated

Question 17

2 types of electron microscope

Answer 17

1. Scanning electron microscope (SEM)

2. Transmission electron microscope (TEM)

Question 18

Scanning electron microscope

Answer 18

• uses a FINE beam of focused electrons to scan a sample’s surface
• 3D configuration

Question 19

transmission electron microscope

Answer 19

• 2D configuration

- uses BROAD beam of electrons to create an image of an internal structure of the sample

Question 20

what types of microscope are capable of viewing all organisms (bacteria, fungi, parasites, viruses)

Answer 20

digital microscopy and fluorescence microscopy

Question 21

Principal stain used for microscopic examination of bacteria and is one of the most important techniques within the microbiology laboratory

Answer 21

Gram Stain

Question 22

• those that take up the basic dye

- stained Blue or violet

Answer 22

gram positive

Question 23

• those that let the basic dye be washed out by the decolorizer and thus take up the secondary counter stain
• stained pink or red

Answer 23

gram negative (-)

Question 24

the one who develop gram staining

Answer 24

Hans Christian Gram

Question 25

use of a single stain to view a sample directly

Answer 25

Simple staining

Question 26

use of two contrasting stains separated by a decolorizing agent

Answer 26

Differential staining

Question 27

use for identification

Answer 27

• gram stain

- acid fast stain

Question 28

visual of structure

Answer 28

• spore stain

- capsule stain

Question 29

Carries NEGATIVE charge

-examples: eosin, nigrosin, carbol fuschin, india ink, malachite green

Answer 29

Acidic stain

Question 30

Carries POSITIVE charge

• examples: crystal violet, methylene blue, safranin etc.

Answer 30

BASIC stain

Question 31

Carries BOTH POSITIVE AND NEGATIVE charge

-examples: geima’s stain, leishman stain, wrights stain

Answer 31

NUETRAL STAIN

Question 32

a basic stain and is regarded as a primary stain in gram staining

Answer 32

Crystal Violet

blue for +and- stain

Question 33

mordant step (to make the reaction of the stain and the microorganisms more intact

Answer 33

Iodine treatment

Question 34

stage wherein we’ll know if the stain that we apply is really meant for the bacteria

Answer 34

Decolorization

Question 35

what is the decolorizing agent for the gram staining

Answer 35

95% alcohol

Question 36

stage wherein after applying the decolorizing agent, the POSITIVE retains its color which is blue or purple and while the gram NEGATIVE loses its staining

Answer 36

Decolorization

Question 37

stage where you apply the secondary stain or counterstain which is safranin

Answer 37

Counter stain with safranin

NOTE: the color of the positive is still blue of purple while the negative will turn pink or red because the safranin

Question 38

Gram Staining procedure

Answer 38

1. Fixation
2. Crystal violet
3. Iodine treatment
4. Decolorization
5. Counter stain with safranin

Question 39

Mechanism of Gram positive and gram negative

Answer 39

Gram positive has a very thick layer of peptidoglycan, and peptidoglycan absorbs more stain compared to gram negative who has thin layer of peptidoglycan so it only absorbs very minimum amount of the primary stain and will be washed out during decolorization
After removal of the primary stain from the decolorizing agent here comes your second dye agent which is Safranin and colors the peptidoglycan of your gram negative into the color of safranin which is red or pink