Question

LABORATORY REPORT EXERCISE 9 Name NEGATIVE STAINING Make a drawing below of one field of bacteria from each side. Use the proper color for the background Congo red Stain Nigrosin Stain 2. WIIIIIII Other than bacteria, what other microorganisms might one encounter in the mouth? 3. Why does the negative stain give a more accurate estimation of bacterial size than other stains? Name a pathogenic spirochete and the disease it causes. Genus Species Disease Why is it difficult to cultivate spirochetes?

Answer 1

2. Other microorganisms include fungus (e.g. Candida albicans), protozoa (e.g. Entamoeba gingivalis) and rarely parasites (e.g.

Gongylonema pulchrum) can be found in our mouth.

3. In negative staining, the sample is not heat fixed, therefore they don't shrink in size and gives an accurate estimation.

4. Genus- Borrelia

Species- burgdorferi

Disease- Lyme

5. It is difficult to culture spirochetes because they cannot be grown in any known culture medium and the only way to keep the organism alive is in an animal system which is both unethical and cumbersome.