Bacterial Infections of the Mouth and Pharynx (6)

Question 1

What are the two major bacterial causes of pharyngitis?

Answer 1

Streptococcus pyogenes (Group A strep) and Corynebacterium

Question 2

What are the virulence factors of Group A strep?

Answer 2

Pili

Toxins (streptokinase, steptodornase, Hyaluronidase, Pyrogenic toin, and Erythrogenic toxin)

Question 3

What does the toxin streptokinase do?

Answer 3

Tissue lysis

Question 4

What does the toxin streptodornase do?

Answer 4

digests DNA

Question 5

What does the toxin hyaluronidase do?

Answer 5

Digests connective tissue

Question 6

What does the pyrogenic toxin do?

Answer 6

Fever, super antigen, and toxic shock

Question 7

What does the erythrogenic toxin do?

Answer 7

Skin rash

Question 8

How is streptococcal pharyngitis Dx made?

Answer 8

Rapid office tests w/ antibody assays

Swab/ culture/ gram stain/ bacitracin sensitivity

Question 9

Should antibiotics be given before streptococcal pharyngitis is confirmed?

Answer 9

No, never!

Question 10

Are the Group A strep hemolysins virulence factors?

Answer 10

No, but they are useful in identification of strep…they produce them on blood agar plates

Question 11

What are 3 oropharnyx complications of a streptococcal sore throat?

Answer 11

Tonsillitis
Peritonsilar abscess
Ludwig’s angina

Question 12

What is Ludwig’s angina?

Answer 12

Swelling of the soft tissue under the tongue that can lead to respiratory distress

Question 13

What complications with strept infections if the infection spreads through the eustachion tubes?

Answer 13

Middle ear infections

Mastoiditis

Meningitis

Question 14

What is scarlet fever caused by? What are the classical symptoms?

Answer 14

Due to exotoxin encoded by a bacteriophage that carries gene for erythrogenic toxin.

Skin rash and tongue rash (strawberry tongue).

Question 15

When does rheumatic fever occur? Is bacteria present?

Answer 15

Occurs about 3 weeks after a strept infection and the lesions are sterile

Question 16

What are the symptoms of rheumatic fever?

Answer 16

Fever, arthritis, and endocarditis/ heart murmur

Question 17

Treatment for streptococcal pharyngitis?

Answer 17

Penicillin G, amoxicillin, erythromycin, cephalosporins

But, treatment is usually not essential because infection is self limiting.

Question 18

Who is at particular risk for Rheumatic Fever?

Answer 18

Children aged 6-15

Autoimmune mediated–> certain HLA types are more susceptible

Question 19

How is Rheumatic fever diagnosed?

Answer 19

The clinical features and the presence of IgM anti-streptolysin O antibody.

Question 20

Does the endocarditis of Rheumatic Fever resolve?

Answer 20

Yes, but it resolves with fibrosis or calcification of the endocardium which leads to permanent valve distortion

Question 21

What bacteria causes dental caries?

Answer 21

An infection with Viridians streptococci

Question 22

How do bacteria cause dental caries?

Answer 22

They produce a high molecular weight carbohydrate that form a biofilm of the tooth surfaces. Organisms break down sugars to make acid that demineralizes the enamel and dentin

Question 23

What is the virulence factor of viridans streptococci?

Answer 23

sugar metabolizing enzymes

Question 24

What are some complications of dental caries?

Answer 24

Pulpitis, abscess and cellulitis

Question 25

What can happen in some patients after treatment for dental caries?

Answer 25

Bacteremia and endocarditis

Question 26

What can help prevent dental caries?

Answer 26

Fluoride (in water and toothpaste)

Low sugar diet

Question 27

How are dental caries and dental abcesses treated?

Answer 27

Removal of decalcified tissue.

Acute abscess can be treated temporarily with Penicillin, erythro, or cephalosporins…but still need dental extraction.

Question 28

What usually causes bacterial endocarditis?

Answer 28

Viridans streptococi or S. aureus

Question 29

How is bacterial endocarditis diagnosed?

Answer 29

Cardiac exams

Satellite infections foci (splinter hemorrhages) under finger nails and in conjunctiva

Possible positive blood cultures

Question 30

What is the treatment for bacterial endocarditis?

Answer 30

Prolonged antibiotics and possible replacement of heart valves.

High mortality rate… 50%

Question 31

What is periodontal disease?

Answer 31

Chronic inflammation in oral tissues that are in contact with dental plaques. Leads to the production of pockets and eventually teeth are lost.

Early stage–>gingivitis (can be reversed)

Question 32

What organism is responsible for periodontal disease?

Answer 32

A mix of anaerobic organisms

Question 33

What causes diphtheria?

Answer 33

Corynebacterium diphtheriae

Question 34

Where does C. diphtheriae infect and how is it spread?

Answer 34

Infect the pharyngeal mucous membrane

Spread by respiratory droplets and direct contact

Question 35

What is the virulence factor of C. diphtheriae? What does the virulence factor do?

Answer 35

Diphtheria toxin which is encoded by a bacteriophage

It causes local and cardiac necrosis (and muscle paralysis)

Question 36

What is the “Pseudomembrane” seen in diphtheria infections?

Answer 36

Necrotic coagulum of bacteria, epithelial cells, fibrin, leukocytes, erythrocytes forming a gray-brown “pseudomembrane” covering oro-pharynx.

Question 37

How is diphtheria diagnosed?

Answer 37

Swab nose & throat, beneath pseudomembrane

Culture requires tellurite media – alert lab that you are testing for C. diphtheriae

PCR confirmation of tox gene

Question 38

Treatment for diphtheria?

Answer 38

Antitoxin (Equine)

Penicillin / erythromycin helps resolution

Mechanical ventilation as needed

Question 39

Prevention of diphtheria?

Answer 39

DTap vaccine and boosters