Chapter 1 Bacterial Taxonomy

Question 1

What are the 7 classic gram (+) bacteria? What shapes do they form? Which ones release spores?

Answer 1

3 cocci

1) Streptococcus (cocci, strips)
2) Enterococcus (cocci, strips)
3) Staphylococcus (cocci, clusters)
4) Bacillus (rods, spores)
5) Clostridium (rods spores)
6) Corynebacterium (rods)
7) Listeria (rods)

Question 2

Two groups of gram (-) cocci?

Answer 2

Neisseria and Moraxella (both are diplococci)

Question 3

Spiral shaped gram (-) bacteria?

Answer 3

Spirochetes

Question 4

Exceptions to gram staining

Answer 4

Mycobacteria - weak gram (+) but only stain w/ acid-fast
Mcoplasma - no cell wall, only a simple plasma membrane (neither positive or negative)
Spirochetes - gram (-) cell wall but too small to be seen with light microscope, have to use darkfield microscope

Question 5

How do the spirochetes protect from immune recognition?

Answer 5

These organisms are stealth due to an extra phospholipid rich outer membrane with few exposed proteins

Question 6

What antibiotics attack at the large subunit of bacterial ribosomes? Small subunit? Why does this not affect human ribosomes?

Answer 6

Bacterial ribosome = 70S (30S + 50S), human = 80S

30S inhibitors: Aminoglycosides, Tetracycline
50S inhibitors: Chloramphenicol, Clindamycin, Erythromycin, Linezolid

“Buy AT 30, CCEL (sell) at 50”

Question 7

Breakdown the shape of gram (-) bacteria

Answer 7

Coccus - neisseria, moraxella
Spiral - spirochetes
Pleomorphic - chlamydia, rickettsiae
Rod - all others

Question 8

Which bacterial do not have the metabolic machinery to utilize oxygen and thus have to steal ATP from their hosts?

Answer 8

Chlamydia and Rickettsia

Question 9

Three enzymes used to break down oxygen products

Answer 9

Catalase (breaks down hydrogen peroxide)
Peroxidase (breaks down hydrogen peroxide)
Superoxide dismutase (breaks down superoxide radical)