Corynbacterium Diptheriae

CORYNEBACTERIUM DIPHTHERIAE

DESCRIPTION

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 58^oC for 10 minutes

· Destroyed by antiseptics, chemical disinfectants.

· Causes diphtheria

DIPHTHERIA

· An acute infectious disease of the URT (nose, tonsils, larynx, pharynx, mucous membranes 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.

RISK FACTORS/CAUSES

· 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

Typical symptoms include thick mucopurulent nasal discharges, fever, cough, hoarseness of the voice, sore throat and 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

1. 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.

2. LARYNGEAL – membrane formation may easily cause suffocation.

3. TONSILLAR – membrane is confined to the tonsils, where absorption of the toxin is moderate.

4. NASAL – membrane formation is rarely associated with severe disease because toxin is poorly absorbed by the lining of the nose.

PREVENTION

· 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.

MANAGEMENT

· 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.