A Gram (+), aerobic, nonsporeforming, club-shaped pleomorphic rods in palisade or Chinese letter character formation.
- Nonmotile, facultatively anaerobic, catalase (+), and ferment carbohydrates
- Inhabits the skin, URT, GIT, and urogenital tract of man
- Grow slowly on enriched media (e.g. cysteine-tellurite agar, serum tellurite agar, Loeffler’s medium and McLeod’s chocolate tellurite agar.
- On blood agar with potassium tellurite, colonies are black. The black color is due to the precipitation of tellurious ions that diffused into the cell wall.
- Resistant to light, dessication, and freezing.
- Easily killed by boiling for one minute or when kept in a temperature of 58oC for 10 minutes
- Destroyed by antiseptics, chemical disinfectants.
- Causes diphtheria
- An acute infectious disease of the URT (nose, tonsils, larynx, pharynx, mucous membran es and the skin) which usually begins as a pharyngitis associated with dull red inflammatory zone of “pseudomembrane formation” and lymphadenopathy.
- Formation of a false membrane is the result of the absorption of the affected area of a potent diphtheria exotoxin which become necrotic, and embedded in the fibrin, red blood cells and white blood cells.
- The toxin can cause remote damages to the heart, liver, and kidneys.
- Incubation period is 2 to 6 days.
- It is common among children.
- Direct contact with a patient or carrier through sneezing or by droplet infection
- Indirectly through use of contaminated fomites of the patient.
SIGNS AND SYMPTOMS
- thick mucopurulent nasal discharges
- hoarseness of the voice
- sore throat
- swelling of the lymphnodes
Although Corynecbacterium Diphtheriae may infect the skin, it rarely invades the bloodstream and never actively invades deep tissue.
TYPES AND CATEGORIES
Four Clinical Forms of Diphtheria
- Faucial. Pharyngeal – The membrane spreads rapidly from the tonsils across the soft palate to the uvula and over the pharyngeal wall into the naso-pharynx.
- Laryngeal – membrane formation may easily cause suffocation.
- Tonsillar– membrane is confined to the tonsils, where absorption of the toxin is moderate.
- Nasal – membrane formation is rarely associated with severe disease because toxin is poorly absorbed by the lining of the nose.
- Isolation of sick persons
- Detection and treatment of healthy carriers with antibiotics for seven days.
- Active immunization against symptomatic diphtheria with diphtheria toxoid during childhood and booster immunization every 10 years throughout life.
- Early use of diphtheria antitoxin for the specific neutralization of exotoxin.
- Antibiotic therapy with penicillin or erythromycin.
- Bed rest and isolation to prevent secondary spread.
- Maintenance of an open airway in patients with respiratory diphtheria.
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