What is diphtheria?
Diphtheria is an acute, toxin-mediated disease caused by Corynebacterium diphtheriae. Unlike the ubiquitous diphtheroids, C diphtheriae lives only on human mucous membranes and skin. The organisms stay in the superficial layers of skin lesions or respiratory mucosa and drive a local inflammatory reaction. Nontoxigenic strains can also cause disease, usually mild and cutaneous.
Pathophysiology
Diphtheria toxin, secreted by toxigenic strains, is a single polypeptide of Mr 58,342.
Within the first few days of respiratory infection, a dense necrotic coagulum of organisms, epithelial cells, fibrin, leukocytes, and erythrocytes forms and advances into a gray-brown adherent pseudomembrane. It does not come off easily; removal exposes a bleeding, edematous submucosa. Palate and hypopharynx paralysis is an early local effect of the toxin. Toxin absorption can cause necrosis of kidney tubules, thrombocytopenia, cardiomyopathy, and demyelination of nerves. In the classic picture, the tonsils or pharynx are the primary focus in more than 90% of patients; the nose and larynx are next.
Statistics and incidences
Diphtheria is endemic in many parts of the world, including the Caribbean and Latin America. Death from mechanical airway obstruction or cardiac involvement with circulatory collapse occurs in about 5% to 10% of patients with respiratory diphtheria, and the rate rises toward 20% in children younger than 5 and adults older than 40 (CDC). When the disease was endemic it mainly hit children younger than 15 years; the epidemiology has since shifted to adults who lack natural exposure in the vaccine era and have low booster rates. Of the 27 sporadic respiratory cases reported in the United States in the 1980s, 70% occurred in people older than 25 years.
Causes
- Nonimmunization. Among nonimmunized populations, diphtheria most often occurs in fall and winter, though summer outbreaks happen.
- Poor socioeconomic conditions. Spread is faster where crowding occurs and immunization rates are low.
- Travel history. International travel poses risk to the unvaccinated or inadequately vaccinated.
Clinical manifestations
Severity depends on the site of infection, immunization status, and toxin spread.
- Tonsils and pharynx. The most common form. Starts with sore throat, usually without systemic complaints. Fever, if present, is usually lower than 102°F; malaise, dysphagia, and headache are not prominent.
- Pseudomembrane. In nonimmune patients, membrane forms after a 2-day to 5-day incubation and grows over the pharyngeal walls, tonsils, uvula, and soft palate. It can extend to the larynx and trachea, causing airway obstruction and suffocation.
- Edema. Marked neck edema can produce a bull-neck appearance with a distinct collar of swelling. The patient throws the head back to relieve pressure on the throat and larynx. The edema obliterates the angle of the jaw, the borders of the sternocleidomastoid, and the medial border of the clavicles.
- Larynx. In a minority of patients the larynx is the initial site, resembling laryngotracheobronchitis. Hoarseness can progress to loss of voice and severe airway obstruction. Nasal diphtheria may start like a common viral URI, sometimes with a foul odor.
- Skin. Cutaneous diphtheria appears at one or more sites, usually over areas of prior minor trauma or bruising.
Assessment and diagnostic findings
Confirm infection by combining isolation of C diphtheriae on culture with toxigenicity testing.
- Bacteriologic culture. Essential to confirm the diagnosis.
- Toxigenicity testing. Use the Elek test to determine whether the isolate produces toxin.
- PCR. Polymerase chain reaction can detect nonviable organisms from specimens taken after antibiotics have started.
Medical management
Address critical care needs and complications first.
- Antitoxin. Specific antitoxin is the mainstay and is given on clinical diagnosis, because it neutralizes free toxin only.
- Isolation. Place the patient in strict isolation (respiratory colonization) or contact isolation (cutaneous only) until 2 subsequent cultures taken 24 hours apart, after therapy ends, are negative.
Pharmacologic management
Give antibiotics alongside the antitoxin.
- Antibiotics. Halt toxin production, treat the local infection, and prevent transmission to contacts.
- Antipyretics. Inhibit central synthesis and release of prostaglandins, returning the hypothalamic set-point to normal.
- Vaccines. Diphtheria toxoid is combined with tetanus and acellular pertussis for children younger than 7 years; active immunization raises resistance to infection.
Nursing management
Assessment
- History. Respiratory diphtheria follows an incubation of 2-5 days (range 1-10d). Early symptoms are nonspecific and often look like a viral URI.
- Physical exam. The patient runs a low-grade fever but appears toxic and may have a swollen neck. Cardiac toxicity typically appears after 1-2 weeks of illness, following improvement in the pharyngeal phase; neurologic toxicity tracks with the severity of the pharyngeal infection.
Nursing diagnoses
- Hyperthermia related to exotoxin release.
- Imbalanced nutrition: less than body requirements related to painful swallowing.
- Ineffective airway clearance related to pseudomembrane blocking the airway.
Planning and goals
- Maintain normal body temperature.
- Demonstrate and maintain normal body weight.
- Maintain a clear airway.
Interventions
- Thermoregulation. Keep the room comfortable, dress the patient in thin sweat-absorbing clothes, push oral fluids, and give antipyretics as ordered.
- Caloric intake. Monitor calorie intake and food quality, offer appetite-stimulating foods, and weigh the patient daily.
- Airway clearance. Auscultate breath sounds and note adventitious sounds, position for maximum lung expansion, assist with chest physiotherapy, and suction secretions as needed.
Evaluation
Goals are met when the patient maintains a normal temperature, a normal body weight, and a clear airway.
Documentation
Record individual findings and factors affecting them, social interactions and behavior, cultural and religious beliefs and expectations, the plan of care, the teaching plan, responses to interventions and teaching, and progress toward desired outcomes.
Frequently Asked Questions
What causes diphtheria?
Diphtheria is caused by toxin-producing strains of the bacterium Corynebacterium diphtheriae. The bacteria spread person to person through respiratory droplets or contact with skin lesions, and the toxin they release drives the serious local and systemic effects (CDC).
What is the pseudomembrane in diphtheria?
The pseudomembrane is a gray-brown, firmly adherent coating of dead cells, fibrin, and bacteria that forms over the tonsils, pharynx, and soft palate. It does not wipe off easily, and trying to remove it exposes a bleeding surface. If it extends into the larynx and trachea, it can obstruct the airway and cause suffocation.
How deadly is respiratory diphtheria?
Death occurs in about 5% to 10% of respiratory diphtheria cases, and the rate climbs toward 20% in children younger than 5 and adults older than 40 (CDC). Most deaths come from airway obstruction or toxin-related heart damage.
How is diphtheria treated?
The mainstay is diphtheria antitoxin, given on clinical suspicion because it neutralizes only toxin that is still circulating. Antibiotics are added to stop toxin production, clear the local infection, and prevent spread to contacts. Patients stay in isolation until two cultures taken 24 hours apart after therapy are negative (CDC).
Can diphtheria be prevented with a vaccine?
Yes. Diphtheria toxoid is given as part of the combined DTaP vaccine for children younger than 7 and Tdap or Td boosters for older children and adults. CDC recommends diphtheria vaccination for people of all ages, with boosters to maintain protection.
Who is most at risk for diphtheria today?
In the United States diphtheria is very rare and is usually linked to international travel to areas where it is still endemic. The highest risk is in people who are unvaccinated or undervaccinated, especially adults who never received boosters and travelers to regions with low immunization coverage.