IIA. Systemic Bacteriology | 3. Streptococci in the oral cavity. S. mutans and caries.

Question 1

I. Basics
1. Where can we find Streptococci?

Answer 1

● Streptococci are found everywhere, but have dominant appearance in oral cavity and upper respiratory tract

Question 2

I. Basics
1. Give the classification of streptoccoci

Answer 2

Question 3

I. Basics
2A. Give the classification of streptoccoci

Answer 3

Question 4

I. Basics
2B. What are the types of streptocci based on Hemolysis on Blood Agar?

Answer 4

Question 5

I. Basics
2C. What are the types of streptocci based on Lancefield classification?

Answer 5

2) Lancefield classification ( → based on group-specific antigens present on cell wall)
- Identified using polystyrene latex particles coated with group-specific antibodies

(+): latex particles agglutinate strongly in the presence of homologous antigen
(-): remain in smooth suspension in the absence of homologous antigen

Question 6

I. Basics
3. What is Pulpal Necrosis?

Answer 6

• Intolerable irritation of the pulp → necrosis
• Pulp exposure to a range of irritans: caries, trauma, chemica, thermic effect
• No symptoms
• X-ray may be negative

Question 7

II. Viridans streptococci
1. What are the features of Viridans streptococci?

Answer 7

• Normal flora of the oral cavity and pharynx
• S. mutans, S. mitis, S. sanguis, S. oralis, S. salivarius
• α-hemolysis

Question 8

II. Viridans streptococci
2. What are the infections caused by Viridans streptococci?

Answer 8

1. subacute bacterial endocarditis (heart valves)
   - due to major oral surgery, tooth extraction
   - antibiotic chemoprophylaxis!
2. caries ! (S. mutans mainly)

Question 9

III. Bacteria isolated from necrotic pulp
1. What are the Obligate anaerobes?

Answer 9

Question 10

III. Bacteria isolated from necrotic pulp
2. What are the featues of Acute periapical periodontitis?

Answer 10

From necrositized pulp due ot the progression of dental caries

Question 11

III. Bacteria isolated from necrotic pulp
3. What are the featues of Chronic periapical periodontitis?

Answer 11

Chronic periapical periodontitis
→ periapical granuloma – osteoporosis around the teeth apex with defined line, teeth will be grey without symptoms

Question 12

III. Bacteria isolated from necrotic pulp
4. What are the features of Dentoalveolar Abscess?

Answer 12

Dentoalveolar Abscess – collection of pus in the pulp or around the root of the teeth
- Remain localized at the root apex and develop into either an acute or chronic abscess or may spread into surrounding tissues

Question 13

IV. Dentoalveolar Abscess
1. What are the 2 types of anaerobes?

Answer 13

• Facultative anaerobes
• Obligate anaerobes

Question 14

IV. Dentoalveolar Abscess
2. What are the Facultative anaerobes that are related to Dentoalveolar Abscess?

Answer 14

1. Gram-positive cocci → Streptococcus mutans group
   - Streptococcus mitis group
   - Streptococcus anginosus group
2. Gram-positive rod → Lactobacillus spp.
   - Actinomyces spp.
3. Gram-negative coccobacilli → Haemophilus spp.

Question 15

IV. Dentoalveolar Abscess
3. What are the Obligate anaerobes that are related to Dentoalveolar Abscess?

Answer 15

1. Gram-positive cocci → Peptostreptococcus sp.
2. Gram-negative cocci Veillonella spp.
3. Gram-negative rods Porphyromonas gingivalis

Question 16

IV. Dentoalveolar Abscess
4. What are the types of Gram-negative rods Porphyromonas gingivalis?

Answer 16

• Porphyromonas endodontalis
• Prevotella oralis
• Prevotella intermedia
• Prevotella melaninogenica
• Fusobacterium nucleatum

Question 17

V. Osteomyelitis of the Jaw
1. What are the features of Osteomyelitis of the Jaw?

Answer 17

• Inflammation of the medullary cavity of the mandible or maxilla
• From dentoalveolar infection or trauma
• Spontaneously pain , tooth motility , Fever

Question 18

V. Osteomyelitis of the Jaw
2. What are the anaerobes causing Osteomyelitis of the Jaw

Answer 18

Endogenous anaerobes are the most common isolates
○ Bacteriodes
○ Prevotella
○ Porphyromonas
○ Streptococcus

Question 19

VI. What are the features of Ludwig’s Angina?

Answer 19

● Secondary to a dental abscess or follows tooth extraction
● Cellulitis of the fascial spaces
● Infection spread to spaces in the neck becomes tense and hard
● Septic fever, Edema, bad breath

Question 20

VI. Periodontal Disease
1. What is Periodontal Disease?

Answer 20

Disorders of supporting structures of the teeth – gingivae, periodontal ligament and supporting alveolar bone

Question 21

VI. Periodontal Disease
2. What are host tissues of Periodontal Disease?

Answer 21

gingivae, periodontal ligament, cementum and alveolar bone

Question 22

VI. Periodontal Disease
3. What are Host defense factors of Periodontal Disease?

Answer 22

Healthy gingiva contain small number of PMN leukocytes
○ Increase in numbers during onset on gingivitis and periodontitis
○ The PMN leukocytes may have both a protective and a damaging effect on host tissues
○ Hypersensitivity reaction can damage the host tissue

Question 23

VI. Periodontal Disease
3. What are Microorganisms that cause Periodontal Disease

Answer 23

dental plaque essential for etiology of common forms of gingivitis and periodontitis
- Microflora
■ Actinobacillus actinomycetemcomitans
■ Tannerella forsythensis
■ Porphyromonas gingivalis
■ Prevotella intermedia/nigrescens
■ Campylobacter rectus
■ Fusobacterium nucleatum
■ Peptostreptococcus micros
■ Treponema spp.

Question 24

VII. Strep. Mutans
1. What are the features of Strep. Mutans?

Answer 24

● Facultative anaerobic, gram positive cocci
● Big contributor to dental decay and caries, it is naturally present
● Mainly found on pits and fissures of teeth in dental plaque
● 39% of total streptococci in oral cavity
● Prevention: good oral hygiene
● Treatment: fluoride – interfere with bacteria adherence

Question 25

VII. Dental plaque
1. What is Dental caries?

Answer 25

Dental caries is the destruction of the enamel, dentin or cementum of teeth due to bacterial activities.

Question 26

VII. Dental plaque
2. Which bacteria are associated with the initiation of dental caries?

Answer 26

Streptococcus mutans and Streptococcus sanguis are most consistently been associated with the initiation of dental caries.
=> They can directly ferment sacharose (the sugar we are eating) and form a specific slimy polysaccharide (glucane) of it, forming a biofilm on tooth enamel.

Question 27

VII. Dental plaque
3. What are the features of Lactobacilli?

Answer 27

Lactobacilli can colonise the plaque and produce lactic acid from the fermentation of sugars and other carbohydrates in the diet of the host.

Question 28

VII. Dental plaque
4. How are caries initiated?

Answer 28

Caries are initiated by direct demineralization of the enamel of teeth due to lactic acid and other organic acids which accumulate in dental plaque.

Question 29

VII. Dental plaque
4. How are caries initiated?

Answer 29

Caries are initiated by direct demineralization of the enamel of teeth due to lactic acid and other organic acids which accumulate in dental plaque.