Microscopy Flashcards
Microscopy findings supportive of a diagnosis of candida?
Presence of: - blastospores - pseudohyphae - neutrophils
Gram +ve yeast
Abundant branched pseudohyphae
Blastoconidia = grape like clusters along the length of the hyphae
can form a biofilm
On microscopy what may the presence of neutrophils in vaginal secretions suggest
an inflammatory response and therefore presence of infection
On microscopy what may the absence of neutrophils in the presence of candida in vaginal secretions suggest
Absence of neutrophils in the presence of Candida is likely to represent colonisation
Appearance of GC on microscopy
monomophicgram negativediplococciwithin polymorphonuclear leukocytes
On a microscope what is the name of the place where you put the specimen that you want to examine
Stage
On a microscope what are the names of the metal parts that hold th slide in place
Stage clips
On a microscope what is the name of the part that you look down
Eyepiece or occular
On a microscope what is the name of the part that holds 2+objective lenses and can be rotated to easily change power (magnification)
The revolving nosepiece or turret
On a microscopewhat is the name of the 3or 4 parts which can be rotated to alter thepower
Objective Lenses
On a microscopewhat is the name of the part where the light comes from
The illuminator
On a microscopewhat is the name of the part which connects the eyepiece to the objective lenses
The tube
On a microscopewhat is the name of two focus knobs
Coarse focus
Fine focus
After Gram staining what colour do Gram-positive bacteria appear
Gram-positive bacteria = violet / purplein colour
after gram staining - retain most of the crystal violet
After gram staining what colour do gram negative bacteria appear
gram-negative bacteria = pink colour
after Gram staining
For gram stain what 4 reagents are used in sequence
sequential application of: crystal violet iodine alcohol safranin
What is the role of crystal violet in gram staining
Crystal violet = the basic dye which acts as the “Primary stain”
It stains all the micro-organisms to appear violet in colour
Applied 1st in gram staining
what is the role of Grams Iodine in gram staining
Gram’s iodine -acts as “Mordant dye”
increases the affinity between the cell and stain by forming a complex with crystal violet known as “CV-I complex”
Applied 2nd
What is the role of 95% Alcohol in the gram staining process
95% Alcohol -acts as the “Decolourizing agent”
functions as lipid solvent
dissolves the lipid present in the cell wall
causes decolourization of the cell by the removal of the CV-I complex from the bacterial cell
Applied 3rd
what is the role of Safranin in the process of gram staining
Safranin = a “Counter stain”
stains the decolourized bacterial cell by giving pink colour to the cell
applied 4th
what are the steps involved with preparing a gram stained slide
- Take a clean dry slide and place one drop of distilled water at the centre.
- Prepare bacterial smear by taking small inoculum from the bacterial culture by the help of the inoculating loop.
- mix the inoculum with the water drop to prepare thin bacterial smear by rotating the inoculating loop in a clockwise and anticlockwise direction.
- heat fixes the bacterial smear under the spirit lamp.
- flood the bacterial smear with crystal violet and allow to stand for 1minute.
- flood the smear with Gram’s iodine.
- add the decolourizing agent i.e. 95% Ethanol to the smear.
- add counter stain i.e. Safranin to the smear and allow to stand for 1 minute.
- wash the slide with water and air dry .
- observe the glass slide under the microscope by adding oil immersion to the stained cells to differentiate gram-positive and negative cells.
Interpretation of Gram Staining - if abacteria cell isstained Violet
Gram-Positive - will stain Violet.
Interpretation of Gram Staining -If a bacteria stains Pink
Gram-negative: will stain Pink.
Interpretation of Gram Staining - what colour does a Gram-Positive bacteria stain
violet
Interpretation of Gram Staining - what colour does a Gram negative bacteria stain
pink
what is a positive gram reaction
stains puple
= Gram positive bacteria
what is a negative gram reaction
Stains pink
= gram negative
What part of thebacterial cell does the gram staining processadd colour to?
the cell wall
what is the the difference between Gram-positive and Gram-negative bacteria
Difference in the cell wall
Gram-positive bacteria - high peptidoglycan content (70-80%) + low lipid content (1-4%) - lacks lipopolysaccharide - lacks porins on the outer membrane -has less periplasmic space
Gram-negative bacteria- low peptidoglycan content (10-20%) and high lipid content (20-30%) - outer membrane is present + contains lipopolysaccharide, porins and has more periplasmic space
