Staining

MicrobiologyProfessor Sidelsky2007

Part Two - StainingHow to Make a SmearStain with Simple StainStain with Gram StainAcid FastSpecialized Staining( Endospore

and Capsule)Negative Staining

How to Make a Smear1.  Label the frosted side of your

slide with your initials, the name of the organism, and the date. 

Turn the slide over and draw an oval on the reverse side with a Sharpie

2. You are going to make the smear on the frosted side

Broth Directions for making a smear

*****If you are using broth follow these directions Flame your inoculating loop. Use aseptic technique and remove the top of the culture

tube, flame the mouth or the culture tube, and dip the loop into the broth.  Make sure that the loop is filled.

Transfer the loopful of broth and bacteria to the slide. Using a circular motion, spread the broth on the slide.

This is now a " smear" Allow the smear to dry When the smear has been allowed to " air dry" , pass the

smear through the flame to " heat fix" - Heat fixation causes the proteins and cell parts to coagulate and stick to the slide.

Let the slide cool.

How to Make a Smear- Plate or Slant

*****If you are using colonies from a plate( Petri Dish) Place a drop of water on the slide. Using aseptic technique, " pick" a colony from the

Plate in order to study the cells that make up a colony

If you are using a slant Using a circular motion spread move the inoculating

loop in a circular motion in the drop of water. Start in the center of the drop and move in a circular motion to the outside of the drop.  The objective is to have fewer cells on the outside of the circle. 

Follow the directions from above Don't forget to " air dry" and to " heat fix" before

staining

Simple StainSimple Stains- Crystal violet and

methylene blue1.  Place a drop(s) of stain over the

smear. Make sure it covers the entire area of the smear.  Leave the stain on the smear for one minute.  Rinse with water from the bottle. 

2. Refer to page 64 for cellular morphology.

The Gram Stain Gram Stain- See Gram Stain Directions on separate page. 

Please refer to pages 71-73 in your laboratory manual.   All staining work is to be done at the sink Care should be taken to work directly over the sink Place drop(s) of crystal violet stain on the smear ( 1 minute) Rock or roll the slide to cover the area Use the water bottle to drip water down the slide

Gram Stain ( II) Place drop(s) of iodine on the slide ( 1

minute) Place drops of alcohol on the slide 10

seconds ( KEY – do not leave on longer than 10 seconds or it will decolorize)

Place drop(s) of saffranin on the slide for 1 minute

Rinse with water from the bottle Let the slide air dry

The Microbe Library – A great Resource

Animation on Gram Stainshttp://www.microbelibrary.org/ASMOnly/details.asp?id=2020&Lang

=

Gram Stain( step by step)http://medic.med.uth.tmc.edu/path/

grampro.htmhttp://www.lumen.luc.edu/lumen/De

ptWebs/microbio/med/gram/tech.htm

Typical Gram Stainhttp://www.uphs.upenn.edu/bug

drug/antibiotic_manual/Gram3.htm

http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/Gramstains/small/tocframeset1.htm

Staphylococcus

Gram Negative bacteria

Gram Stain animations and information

http://www.microbiologybytes.com/video/Gram.html

Bacterial Cell Morphology

Acid Fast Stains( Mycobacterium)

Acid- Fast Stain Carbol Fuschin Stain is a red stain that is soluble in a lipid

environment. The outer cell wall of the mycobacterium is mycolic acid

The stain can be absorbed by placing the stain over a beaker boiling water. Heat assists the stain inits penetration of the waxy cell wall

Cool and rinse with cool water Add acid- Alcohol drop by drop until the alcohol runs alost

clear. Rinse with water Counterstain by applying methylene blue for at least two

minutes

Acid Fast Staining A shows cells that

are stained with methylene blue – These re non acid fast

B shows cells that are stained with carbol fuschin which is retained in the lipid cell walls

Acid Fast

Differential Staining( Spores) Add Malachite Green to slide and steam over a

beaker of boiling water ( beaker may be placed on a hot plate) If stain starts to evaporate, add additional stain. Stain should remain on for 2-3 minutes

Remove slides from hot plate and cool Rinse with water

Counter stain with Saffranin for a minute. Rinse with water

Endospore structure

Endospore

Capsule stain Crystal violet is applied to the bacterial

smears The decolorizing agent is Copper sulfate(

20%) which washes the primary stain out of the capsule without removing the stain from the cell wall

Capsule stain( Klebsiella pneumoniae and Streptococcus pneumoniae)

Negative staining Place a drop of nigrosin on the end of a

slide- Use a plain slide Use the inoculating loop to mix some of

the bacterial culture with the drop of stain Use a clean slide. Hold at a 45o angle

against the drop. The drop will spread along this line

Push the slide away from the previously spread drop

Negative staining

Negative staining