Diphtheria

Diphtheria An acute bacterial disease that can infect the body in two areas the throat (respiratory diphtheria) and the skin (cutaneous diphtheria).

Etiologic Agent:

CORYNEBACTERIUM DIPHTHERIAE (Klebs Leoffler bacillus)

a toxin- producing organism; manufactures an exotoxin which is responsible for major pathologic changes.Gram positive non-sporulating, and generally aerobic.

the bacilli the superficial tissue with very limited extension beyond the mucous membrane, but soluble toxin is capable of producing severe fatal sequelae.It is unstable and easily destroyed by light, heat and aging.It is capable of damaging muscles, especially the cardiac, nerve kidneys, the liver and other tissues.

Incubation period:

After being exposed to the bacterium, it usually takes 2 – 5 days for symptoms to develop.Period of Communicability

Variable; more than 2 – 4 weeks in untreated patients or 1 -2 days in treated patients.Source of infection:Discharges from the nose, pharynx, eyes or lesions on other parts of the body of infected persons.Mode of Transmission:Contact with patients or carrier, or with articles soiled with discharges of infected persons.

Pathogenesis/ Pathology:

The toxin is absorbed into the mucous membrane and causes destruction of the epithelium and superficial inflammatory response takes place.Necrotic epithelium become embedded in exuding fibrin so that grayish pseudomembrane is formed by leukocytes, fibrin and necrotic tissues and microorganisms that adhere to the underlying tissues and leave a raw bleeding when detached.

The larger the membrane, the more toxin are present in the blood stream and in the tissues.

Commonly seen over the tonsils, pharynx or larynx, so that any attempt to remove the pseudomembrane, exposes and tears the capillaries, thus resulting in bleeding.The bacilli within the membrane continue to produce toxins actively that results in distant damage, particularly parenchymatous degeneration, fatty infiltration and necrosis in the muscles of the heart, liver, kidney, and adrenals, sometimes accompanied by gross hemorrhage.The toxins also produce nerve damage resulting in paralysis of the soft palate, eye muscles or extremities.

Types:

1. Nasal – with serosanguinous secretions from the nose with foul smell.2. Tonsilar-low fatality rate.3. Nasopharyngeal – more severe type

Cervical lymph nodes are swollenNeck tissues are edematous that result to the appearance of “Bull’s neck”With marked degree of toxemiaHighest fatality rate

4. Wound or cutaneous diphtheria – affecting mucous membrane and any break on the skin.

Clinical Manifestations:

The onset of the disease is insidious with feeling of fatigue, malaise, slight sore throat and elevation of temperature usually not exceeding 38 degrees Celsius. Inflammatory reaction is initiated by the body and exudates consisting of leukocytes, RBC, and necrotic tissues begin to form.The exudates forming the membrane is grayish in appearance as it begin to form. As it thickens, it becomes dull white.Cervical adenitis with tenderness of the glands occur.Body malaise, weakness, and apathy with rapid pulse rate that become disproportionate to the low grade fever.In severe cases, the entire neck become swollen with edema extending to the chest.The swelling of the neck has given the name “bull’s neck” form.

If the membrane forms in the larynx, it may extend to the trachea resulting in respiratory problem which tracheotomy maybe necessary.After administration of anti-toxin, the membrane begin to curl at the edges, begin to separate and flakes off in large pieces.

Other common symptoms of respiratory diphtheria include:

Breathing difficulty Husky voiceIncreased heart rateStridor (a shrill breathing sound heard on inspiration)Nasal drainage/secretions (serosanguinous with foul smell)Swelling of the palateLow grade fever

Symptoms of skin or cutaneous diphtheria are usually milder and may include yellow spots or sores ( similar to impetigo) on the skin.

Complications :

Myocarditis caused by action of diphtheria toxin on the heart muscles.Polyneuritis ; that include; paralysis of the soft palate, paralysis of the ciliary muscles of the eye, pharynx, larynx, or extremities.Airway obstruction may lead to death through asphyxiation.

Diagnostic Tests:

Swab from nose and throat or other suspected lesionsVirulence testSchick test Molony testLoefler slant

Treatment Modalities:

Specific treatment of diphtheria is determined by the physician based on:

Overall health and medical history Extent of the condition Tolerance for specific medications, procedures and therapies

1. Penicillin is usually effective in treating respiratory diphtheria before it releases toxins in the blood.

2. Anti-toxin can be given in combination with penicillin. Skin testing is necessary before the administration of anti-toxin.3. Erythromycin 40 mg/kg 4 doses x 7-10 days.

4. Supportive therapy

Maintenance of adequate nutritionMaintenance of adequate fluid and electrolyte balanceBed restIn presence of laryngeal obstruction, tracheostomy is usually done

Prevention:Mandatory reporting cases.Patients are isolated for minimum of fourteen days from the onset of the disease until three cultures from the nose and throat are reported negative.Contact with children and food handling should be restricted until bacteriologic examinations of cultures are reported negative.Children under 5 years old should be given booster dose of diphtheria tetanus vaccine.Mandatory DPT immunization for babies.