Bacterial Infections of the Mouth and Pharynx (6) Flashcards
What are the two major bacterial causes of pharyngitis?
Streptococcus pyogenes (Group A strep) and Corynebacterium
What are the virulence factors of Group A strep?
Pili
Toxins (streptokinase, steptodornase, Hyaluronidase, Pyrogenic toin, and Erythrogenic toxin)
What does the toxin streptokinase do?
Tissue lysis
What does the toxin streptodornase do?
digests DNA
What does the toxin hyaluronidase do?
Digests connective tissue
What does the pyrogenic toxin do?
Fever, super antigen, and toxic shock
What does the erythrogenic toxin do?
Skin rash
How is streptococcal pharyngitis Dx made?
Rapid office tests w/ antibody assays
Swab/ culture/ gram stain/ bacitracin sensitivity
Should antibiotics be given before streptococcal pharyngitis is confirmed?
No, never!
Are the Group A strep hemolysins virulence factors?
No, but they are useful in identification of strep…they produce them on blood agar plates
What are 3 oropharnyx complications of a streptococcal sore throat?
Tonsillitis
Peritonsilar abscess
Ludwig’s angina
What is Ludwig’s angina?
Swelling of the soft tissue under the tongue that can lead to respiratory distress
What complications with strept infections if the infection spreads through the eustachion tubes?
Middle ear infections
Mastoiditis
Meningitis
What is scarlet fever caused by? What are the classical symptoms?
Due to exotoxin encoded by a bacteriophage that carries gene for erythrogenic toxin.
Skin rash and tongue rash (strawberry tongue).
When does rheumatic fever occur? Is bacteria present?
Occurs about 3 weeks after a strept infection and the lesions are sterile
What are the symptoms of rheumatic fever?
Fever, arthritis, and endocarditis/ heart murmur
Treatment for streptococcal pharyngitis?
Penicillin G, amoxicillin, erythromycin, cephalosporins
But, treatment is usually not essential because infection is self limiting.
Who is at particular risk for Rheumatic Fever?
Children aged 6-15
Autoimmune mediated–> certain HLA types are more susceptible
How is Rheumatic fever diagnosed?
The clinical features and the presence of IgM anti-streptolysin O antibody.
Does the endocarditis of Rheumatic Fever resolve?
Yes, but it resolves with fibrosis or calcification of the endocardium which leads to permanent valve distortion
What bacteria causes dental caries?
An infection with Viridians streptococci
How do bacteria cause dental caries?
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
What is the virulence factor of viridans streptococci?
sugar metabolizing enzymes
What are some complications of dental caries?
Pulpitis, abscess and cellulitis
What can happen in some patients after treatment for dental caries?
Bacteremia and endocarditis
What can help prevent dental caries?
Fluoride (in water and toothpaste)
Low sugar diet
How are dental caries and dental abcesses treated?
Removal of decalcified tissue.
Acute abscess can be treated temporarily with Penicillin, erythro, or cephalosporins…but still need dental extraction.
What usually causes bacterial endocarditis?
Viridans streptococi or S. aureus
How is bacterial endocarditis diagnosed?
Cardiac exams
Satellite infections foci (splinter hemorrhages) under finger nails and in conjunctiva
Possible positive blood cultures
What is the treatment for bacterial endocarditis?
Prolonged antibiotics and possible replacement of heart valves.
High mortality rate… 50%
What is periodontal disease?
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)
What organism is responsible for periodontal disease?
A mix of anaerobic organisms
What causes diphtheria?
Corynebacterium diphtheriae
Where does C. diphtheriae infect and how is it spread?
Infect the pharyngeal mucous membrane
Spread by respiratory droplets and direct contact
What is the virulence factor of C. diphtheriae? What does the virulence factor do?
Diphtheria toxin which is encoded by a bacteriophage
It causes local and cardiac necrosis (and muscle paralysis)
What is the “Pseudomembrane” seen in diphtheria infections?
Necrotic coagulum of bacteria, epithelial cells, fibrin, leukocytes, erythrocytes forming a gray-brown “pseudomembrane” covering oro-pharynx.
How is diphtheria diagnosed?
Swab nose & throat, beneath pseudomembrane
Culture requires tellurite media – alert lab that you are testing for C. diphtheriae
PCR confirmation of tox gene
Treatment for diphtheria?
Antitoxin (Equine)
Penicillin / erythromycin helps resolution
Mechanical ventilation as needed
Prevention of diphtheria?
DTap vaccine and boosters
