chapter 27-2

Question 1

Use of hand bacteria for forensic identification

Answer 1

1. Individuals harbor very distinct communities.
2. Your hand communities do not change appreciably over time.
3. Bacterial communities remain on touched objects for weeks.
4. We can use bacteria to match touched objects to owner with >90% accuracy.

Question 2

The Mouth microbiome

Answer 2

Contains organisms that survive mechanical removal by adhering to gums and teeth.
Saliva production = 1 to 100 mL per hour (protection from microbes).
Saliva contains lysozymes, lactoferrin, protease inhibitors…

Question 3

Normal microbial flora of the oral cavity

Answer 3

Food and epithelial debris provide nutrients on and around oral surfaces.
Changes in normal flora depending on age of host:
-1st year of life: aerotolerant anaerobes.
-After teeth: shift towards anaerobes adapted for surface of teeth and gingival crevices.

Question 4

Teeth and dental plaque

Answer 4

Bacterial colonization of teeth begins with attachment of bacteria to film of glycoproteins deposited by saliva.
Extensive growth of these organisms results bacterial layer called dental plaque.
Top of tooth: aerobic, gram positive.
Root of tooth: anaerobic, gram negative.
Fluoride increases resistance to acid decalcification.

Question 5

Oral numbers

Answer 5

100 bacteria per tongue epithelial cell.
Greater than 500 species per mouth.
Dental plaque: biofilm bacterial community on teeth.
Tartar: mineralized plaque

Question 6

Normal microbial flora of the oral cavity: Streptococci example

Answer 6

Extensive growth of oral microbes, especially streptococci, results in a thick bacterial layer.
As plaque continues to develop, anaerobic bacterial species begin to grow.

Question 7

Dietary

Answer 7

Diet rich in fermentable carbohydrates: more acid production.
Diet rich in proteins: reduces mouth acidity, also some putrescine and cadaverine production.