MICRO LAB 5 - Acid-Fast, Capsule, and Endospore PRE-LAB Quiz

How many total smear preparations are you going to make in this lab? How many different organisms will you use to make a single smear this week in lab?

2 and 2

What magnification will you be using to view your Acid Fast stains?

Oil immersion 1000x

How many different types of staining methods will you be performing in lab this week

1

How many types of staining methods will you be viewing and illustrating this week?

3

Identify the reaction of the cells pictured here.

Label A is pointing to blue bacterial cells, Label B is pointing to reddish-fuchsia colored bacterial cells.

A is non-acid fast; B is acid-fast

Identify the survival strategy pictured here.

The image contains a purple negative stain with purple bacilli with white "halos" surrounding them.

capsules

What is the function of the special features stained with the method shown here?

The image shows pinkish red bacilli with smaller structures that are stained blueish-green

survive harsh environments, germinate into new cells when conditions are safe

What is the function of capsules?

Evade detection by white blood cells

Acid-fast bacteria include which medically relevant genera of bacteria?

Mycobacteria; Norcardia

We use the ________________ method for Acid fast stains in the lab. It is safer because we use ___________ to fix the primary stain.

Kinyoun; tergitol detergent

Capsule stains are an example of what type of stain?

 negative stain

What is the most critical step in an acid-fast stain

applying the primary stain

 

Which of the reagents in the image above is the counterstain in an acid-fast stain?

Reagent A is labeled carbol fuchsin, Reagent B is labeled TB decolorizer, and reagent C is labeled Methylene blue.

c

What chemical is used as a decolorizer in acid-fast stains?

acid alcohol

Acid fast prep results

What method did we employ in performing the acid fast stain

what step is the most critical in the acid fast stain

name 2 genera of bacteria that contain acid fast organisms

What is the function of bacterial endospores

bacterial endospores results

What is the composition and function of bacterial capsules

Bacterial capsules results

Slides Characteristics

Quorum sensing

• this serratia marsenscens culture shows evidence of a pheomenon known as quorum sensing, in which production of pigment is density dependent

• it only produces pigment when there are enough bacteria present in a colony

Swarming

• this is a pure culture of a highly motile bacteria

• ONE drop of inoculum was placed at the center of the plate

• after 24 hour incubation the “swarm” has covered the entire plate with a thin, transparent film of growth

Too Thick

• the bacteria on this plate are too thick to discern colony morphology

• this can be caused by:

  • too large an inoculation; multiple loops from stock broth or too much inoculum from a plate

  • failure to flame between loops

Pigment Production

• some bacterial colonies produce pigment

• S.marcesens, K.rosea, K.-rhizo, S.aurantiaca

Contaminant

• can come from a “drop-in: which settled onto the agar when the plate was opened during inoculation

• rim is a very common “hiding place”

• growth can be clear/ very tiny

Pure Cultures

Staphylococcus epidermis: punctiform, entire, white

Escherichia coli: irregular, entire, white

Bacillus subtillis- irregular, undulate, off-white