GRAM -VE

Question 1

Name 3 gram negative cocci

Answer 1

1. Neisseria
2. Moraxella
3. Veillonella

Question 2

What type of bacteria is Neisseria?

Answer 2

Gram-negative cocci that is facultative aerobic

Question 3

Appearance of Neisseria on gram stain?

Answer 3

Pink;

Cocci - found in pairs, tetrads, short chains & clusters

Question 4

List 2 species of Neisseria that are pathogens

Answer 4

1. Neisseria gonorrhoeae

2. Neisseria meningitidis

Question 5

List 2 species of Neisseria that can be found in the oral cavity

Answer 5

1. Neisseria subflava

2. Neisseria sicca

Question 6

Are the Neisseria species early or late colonizers of tooth?

Answer 6

Early

Question 7

Name a similarity and a difference between Neisseria subflava and Neisseria sicca

Answer 7

S: N. subflava and N. sicca are saccharolytics and polysaccharide producing bacteria found in the mouth
D: N. subflava produces a yellow-green pigment but N. sicca does not produce pigment.

Question 8

State a difference between Neisseria and Moraxella

Answer 8

Neisseria is saccharolytic (i.e. produces polysaccharide) but Moraxella is asaccharolytic (i.e. does not produce polysaccharide)

Question 9

Name a species of Moraxella

Answer 9

Moraxella catarrhalis

Question 10

What do most strains of Moraxella produce? Why is that a danger?

Answer 10

Most strains produce B-lactamase –> complicates antibiotic therapy

Question 11

Where can Moraxella catarrhalis be found?

Answer 11

Commensal of the mouth and upper respiratory tract

Question 12

What is Moraxella catarrhalis a significant pathogen of?

Answer 12

Meningitis, endocarditis, otitis media, maxillary sinusitis

Question 13

Similarity between Moraxella and Veillonella

Answer 13

Both are asaccharolytics (both do not ferment carbohydrates)

Question 14

Where can Veillonella be found?

Answer 14

Mouth and dental plaque

Question 15

Function of Veillonella

Answer 15

Catabolises lactic acid to weaker organic acids (acetate and propionate); hence raising pH of the oral cavity

Question 16

Name the most common species of Veillonella

Answer 16

Veillonella parvula

Question 17

Where can veillonella parvula be found?

Answer 17

Oral cavity and intestines

Question 18

Name 3 species of Veillonella

Answer 18

1. Veillonella Parvula
2. Veillonella Dispar
3. Veillonella Atypica

Question 19

Define GNAB

Answer 19

GNAB = Gram negative anaerobic bacteria - They are a large proportion of oral bacteria found especially in the gingival sulcus and periodontal pocket that is difficult and fastidious to study.

Question 20

Name 3 motile GNAB

Answer 20

1. Selenomonas
2. Centipeda
3. Helicobacteria

Question 21

Name 6 non-motile GNAB

Answer 21

1. Bacteriodes
2. Porphyromonas
3. Prevotella
4. Tannerella
5. Fusobacterium
6. Leptotrichia

Question 22

What are selenomonas associated with?

Answer 22

Periodontitis / Periodontal disease

Question 23

Describe the appearance of Selenomonas

Answer 23

Cresent (moon-shaped) with many flagellae

Question 24

Name 3 species of Selenomonas

Answer 24

1. Selenomonas Sputigena
2. Selenomonas Flueggei
3. Selenomonas Noxia

Question 25

Name a species of Centipeda

Answer 25

Centipeda Periodontii

Question 26

Describe the appearance of Centipeda

Answer 26

flagellae arising from all around the cell

Question 27

Name a species of Helicobacter

Answer 27

Helicobacter pylori

Question 28

What does helicobacter pylori cause?

Answer 28

gastritis, gastric cancer, peptic ulcers

Question 29

Describe the appearance of bacteroides on a CBA

Answer 29

Produces a dark pigment

Question 30

Name a species of bacteroides. Where can it be found?

Answer 30

Bacteroides fragilis; found in mouth and GI tract (esp in the colon)

Question 31

Where does the dark appearance of certain species of bacteria on CBA come from?

Answer 31

Dark appearance comes from the iron scavenging molecules on the surface which require an external heme as the iron source

Question 32

Where can porphyromonas be found?

Answer 32

Exclusively in gingival sulcus and periodontal pocket

Question 33

Name a species of Porphyromonas and the associated disease

Answer 33

Porphyromonas gingivalis; frequently associated with periodontitis

Question 34

Name 3 black pigmented bacteria

Answer 34

1. Porphyromonas gingivalis 2. Prevotella intermedia 3. Prevotella nigrescens

Question 35

Are porphyromonas saccharolytic or asaccharolytic?

Answer 35

Asaccharolytic

Question 36

What is the source of energy for Porphyromonas?

Answer 36

Environmental amino acids and peptides - Porphyromonas produce proteases to access them. They degrade serum albumin, immunoglobulins, haemoglobins and host tissue proteins

Question 37

Name 3 species of Prevotella

Answer 37

1. Prevotella Intermedia 2. Prevotella Nigrescens 3. Prevotella Dentalis

Question 38

Are Prevotellas saccharolytic or asaccharolytic?

Answer 38

Saccharolytic - Breaks down sucrose into acetic acid and succinic acid

Question 39

Which Prevotella species correlates with periodontitis severity?

Answer 39

Prevotella intermedia

Question 40

Which Prevotella species is present in high numbers at healthy sites?

Answer 40

Prevotella Nigrescens

Question 41

List the bacteria involved in gum disease in sequence

Answer 41

1. Streptococcus 2. Actinomyces 3. Porphyromonas gingivalis & Prevotella intermedia

Question 42

How do the conditions for bacterial growth below the gingival margin differ from the tooth surface?

Answer 42

1. Conditions are more anaerobic (requires carbon dioxide) | 2. Nutrients come from the gingival tissues rather than food and saliva (gingival crevicular fluid)

Question 43

Describe the structure of Spirochaetes

Answer 43

Spirochaetes are helical shaped bacteria with a central protoplasmic cell and 3-5 axial filaments or flagellae within the outer cell envelope

Question 44

What disease does a fuso-spirochaetal complex cause?

Answer 44

ANUG (Acute Necrotizing Ulcerative Gingivitis)

Question 45

Bacteria involved in Acute Necrotising Ulcerative Gingivitis

Answer 45

Fusobacterium nucleatum | Treponema vincentii

Question 46

Periopathogens

Answer 46

Treponema Denticola Porphyromonas Gingivalis Aggregatibacter Actinomycetemcomitans