1. Microbiology review

4. • 8. What does “parfocal” mean? Is the
microscope used in the laboratory a “parfocal”
microscope?
Parfocal is that a microscope stays in focus
when you change the objective lens.
• Parcentric?
• Stays center even after you change the focus.
• Whats your TA’s Name and where to fid him.

5. • Know the difference between gram + and –
• Know what the different reagents in the gram
stain and what they accomplish.
• Know what a basic (positive) and a
acidic(negative) stain look like. And what they
stain.

6. • Know all the media we used and what positive
test means and what a negative test means.
Also when a organism doesn’t grow what that
means.
• Know selective and deferential definitions.

7. • Macconkey agar
• Positive means
• If it grows it means
• EMB
• If it grows ?
• If is positive?

8. • MSA (mannitol salt agar )
• Positive means ?
• Growth Means ?
• Mitis – salavarius
• Colonies are blue?
• If no growth?
• PEA
• Grow means?

11. Stains
• Positive stain
• Stains the cell also known as the basic stain
• Negative stain
• Stains all the back ground not the cells themselves.
• Differential stain?
• Differentiates the cells some how due to a structure or some type of
phenotype characteristics.
• Capsule stain uses what 2 types of stains
• Manevals stain
• positive stain.
• Congo red
• Negative
• Endospore stain uses what stains
• Malachite green and safernin

12. Gram stain
• Gram stains
• Primary stain
• Crystal violet
• Mordant
• Grams iodine
• Decolorizer
• 95% ethanol alcohol
• Counter stain
• Saferin

13. Gram negative Media
• EMB
• Macconkey agar
• Hektoen
• Urea

14. EMB
• A positive test means what ?
• growth of Gram + organisms. Additionally, the
medium contains lactose which can be utilized
by lactose fermenters as a carbon and energy
source.
• Grow means its what ?
• That it’s a gram -.

15. EMB

16. Macconkey’s
• What does growth mean ?
• That is a gram -
• What does positive test mean?
• above pH 8. Like EMB, this medium contains lactose
and those organisms that can utilize lactose produce
acids. The acid production results in a lower pH in the
medium and a change in the color of the medium to
yellow. Neutral red is the ph indicator
• The selective molecule is bile salts

17. Macconkey agar

18. Hektoen enteric agar
• MacConkey’s agar. However, this differs from
MacConkey’s agar because it also has ammonium
sulfate and sodium thiosulfate in it.
• These chemicals are indicator molecules because they
react with H2S released from the breakdown of
peptones in the medium and turn the H2S producing
colonies black (indicating that H2S was present).
• The pH indicator in this medium is bromothymole blue.
• When bacteria use the lactose and sucrose in the
medium acid is produced and the medium’s color
changes from a blue/green
• It has bile salts as the selective indicator molecule

19. Hectoen enteric agar

20. Urea broth
• If its positive
• the organism has urease .
• If negative it doesn’t poses urease.
• Has phenol red as a ph indicator

21. Urea broth

22. Gram positive
• MSA (man
• PEA
• Mitis-salavarius

23. Mitis-salavarius
• Grows up mainly gram positive mainly
streptococcus.
• If the colonies turn blue what does this mean?
• It incorporates the trypan blue from taking in
sucrose peptones and all the different
carbohydrates.

24. Mitis- salavarius

25. PEA
• This is a selective media it doesn’t allow
which type of bacteria to grow?
• Gram negatives.
• What is incorporated in to this to allow only
gram positives to grow.

26. PEA

27. Mannitol salt agar
• IF an organims grows this means that the
organism is a halophile.
• If it changes color which is a positive test this
means that the organism uses mannitol as its
main carbon source.
• has phenol red indicator.
• It has NaCl as a inhibitory molecule.

28. Mannitol salt agar