Diphtheria
Acute, highly contagious, and toxin-mediated, diphtheria usually infects the respiratory tract, primarily involving the tonsils, nasopharynx, and larynx. Cutaneous, stool, and wound diphtheria are the most common types in the United States, often resulting from nontoxigenic strains. The GI and urinary tracts, conjunctivae, and ears are seldom involved.
Anticipating diphtheria hazards
When caring for a patient with diphtheria, be alert for these potentially life-threatening hazards:
anaphylaxis after administering antitoxin, antibiotics, or both; monitor for signs and symptoms, and keep epinephrine 1:1,000 and resuscitative equipment handy
thrombophlebitis after giving erythromycin
airway obstruction, which could require a tracheotomy
shock, which can develop suddenly as a result of systemic vascular collapse, airway obstruction, or anaphylaxis
myocarditis, which causes a sudden decrease in pulse rate, an irregular heartbeat, and pallor
heart murmurs and ECG changes, especially ventricular fibrillation (be prepared to intervene immediately because ventricular fibrillation is a common cause of sudden death in diphtheria patients).
Thanks to effective immunization, diphtheria has become rare in many parts of the world, including the United States. A massive and expanding epidemic of diphtheria in the former Soviet Union has been ongoing since 1990, especially in individuals age 15 and older. In the tropics, cutaneous diphtheria is more common than respiratory diphtheria. It’s particularly likely to strike in areas where crowding and poor hygienic conditions prevail.
Causes
Diphtheria is caused by Corynebacterium diphtheriae, a gram-positive rod. Transmission usually occurs through intimate contact or by airborne respiratory droplets from apparently healthy carriers or convalescing patients. Many more people carry this disease than contract active infection.
Diphtheria is more prevalent during the colder months because of closer person-to-person contact indoors, but it can be contracted at any time of the year.
Complications
The extensive pseudomembrane formation and swelling that occur during the first few days of the disease may cause respiratory obstruction in addition to other life-threatening complications. (See Anticipating diphtheria hazards.) The disease may also be complicated by polyneuritis (primarily affecting motor fibers but possibly also sensory neurons), encephalitis, cerebral infarction, bacteremia, renal failure, pulmonary emboli, and bronchopneumonia caused by C. diphtheriae
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