Introduction
Diphtheria is caused by Corynebacterium diphtheria, a club-shaped, nonencapsulated, non-motile bacterium. Not getting immunized when young is a risk factor for this illness. The disease primarily affects the integumentary system, the respiratory system, and it may exist in an asymptomatic carrier form. The organism only exists in humans and is found in the upper respiratory tract. Airborne droplets carry the microbes.
The creation of exotoxins is essential to the organism’s pathogenicity. Although occurrences of the disease are uncommon in the United States, they are common internationally and primarily occur in tropical regions. The thick, adhesive, gray pseudomembrane covering the tonsils and throat is found in patients. The essential steps in the diagnosis process are to isolate the organism, culture it, and reduce its ability to produce toxins. Isolating the patient and administering antibiotics and an antitoxin are part of management. The routine vaccination schedule includes both the acellular pertussis vaccine and diphtheria toxoid, which is administered as a combination of diphtheria and tetanus toxoid.
Cause and Epidemiology
Gram-positive Corynebacterium diphtheria is a club-shaped, nonencapsulated, nonmotile bacillus that is grouped in palisades or in a V- or L-shaped configuration. These gram-positive rods do not generate spores. In addition to Corynebacterium diphtheria, this pathogen also causes cutaneous and, in rare instances, respiratory diphtheria.
The majority of cases are now seen in people with low socioeconomic status, living in crowded conditions, not having received vaccinations, having traveled to endemic regions, and having coexisting conditions, particularly in South-east Asia and Africa. The incidence of the disease has rapidly decreased since the introduction of the vaccine.
The disease has no racial or sexual predispositions. Though it primarily affects children under the age of twelve, diphtheria is thought to be a childhood disease. However, persons over 40 and those who have coexisting medical conditions are also susceptible to infection. If someone is not up to date on their booster doses of vaccinations, their chance of contracting the infection rises as their antibody to the bacterium gradually wears off.
Symptoms
Diphtheria first manifests as nonspecific flu-like symptoms such as fever, sore throat, and cervical lymphadenopathy. The usual incubation period is 2 to 5 days (ranges from 1 to 10 days). In the majority of cases, the patients’ histories point to travel from an endemic zone with no vaccination records. In such circumstances, the provider should be aware of the disease’s most visible characteristics, namely the thick, gray, adherent pseudomembrane across the tonsils and throat. The condition frequently involves the respiratory tract. In the case of cutaneous diphtheria, ulcerating skin lesions with a gray membrane are seen. These lesions do not spread or penetrate the tissues around them. The cutaneous lesions are located in previously wounded tissues from trauma or earlier dermatologic lesions.
Laboratory diagnosis is accomplished through laboratory testing, which must be linked with physical examination findings in order to provide a rapid and conclusive diagnosis. Diphtheria can begin with vague upper respiratory symptoms such as fever, sore throat, dysphagia, and headache. These vague signs and symptoms typically have a lengthy list of differentials and provide a diagnostic quandary. Thus, throughout the history taking process, the patient’s travel history and vaccination status can be useful in narrowing down the differential diagnosis. The presence of a pseudomembrane is a significant indication of diphtheria.
Differential Diagnosis, Prognosis and Complications
Diphtheria must be distinguished from other upper respiratory tract infections with similar symptoms. Other differentials to consider while diagnosing diphtheria include as follows:
- Epiglottitis: This is an acute inflammation of the oropharynx’s supraglottic area, characterized by inflammation of the epiglottis and associated structures.
- Retropharyngeal Abscess: This condition causes high spiking fevers and necessitates immediate drainage.
- Angioedema: This is characterized by global swelling caused by involvement of the lower dermis and subcutaneous/submucosal tissues.
- Infectious Mononucleosis: It causes lethargy, malaise, sore throat, fever, nausea, anorexia, and coughing. Children with fever, pharyngitis, and lymphadenopathy are the classic triad.
- Pharyngitis: It presents with a sore throat that is usually sudden in onset, odynophagia, fever, and cough.
- Oral Candidiasis: Grayish pseudomembrane, in the case of diphtheria, must be differentiated from oral candidiasis.
The course of the infection (prognosis) depends on multiple factors. Age of onset and duration of onset of symptoms because high mortality rates are seen in individuals younger than five years and those older than 40 years and in cases with onset of duration greater than four days respectively. Cardiac Involvement is associated with a very poor prognosis, particularly AV and left bundle-branch blocks while high mortality rate is also seen in cases of systemic involvement.
In terms of complications, myocarditis and neuritis are the most common complications, and death occurs in 5%-10% of patients. A severe consequence is the creation of a pseudomembrane in the upper respiratory tract, which causes breathing obstruction and necessitates rapid mechanical ventilation and intubation. These complications include: Cardiovascular and neurological complications. Diphtheria’s neurological complications include nerve weakening or paralysis, particularly impacting the cranial nerves and also affecting the nerves in the extremity, resulting in muscle weakness in the extremity. The involvement of the pharyngeal and soft palate muscles results in the regurgitation of foods and fluids into the nose. Encephalitis caused by diphtheria complications is reported in children in uncommon cases.
Treatment and Management
Antitoxins and antibiotics are the two most essential therapy techniques for diphtheria. Aside from these two, the patient should be evaluated for respiratory and cardiovascular instability. When a patient is suspected of having diphtheria, antitoxin should be administered clinically rather than waiting for laboratory confirmation. Suspected cases must be kept in isolation, and adequate droplet measures must be implemented. Furthermore, the patient should be evaluated for respiratory distress and, if necessary, a definitive airway should be provided. Cardiac monitoring is also an important part of early management.
Diphtheria antitoxin is a horse-derived antiserum. Antitoxin works by neutralizing unbound diphtheria toxin in the bloodstream. Antitoxin has no involvement in neutralizing the toxin once it is attached to the cell membrane. The antitoxin dose is determined by the clinical stage and severity of the illness. It can be taken either intramuscularly or intravenously. Before delivering the antitoxin, the patient must be checked for hypersensitivity, and emergency anaphylaxis drugs must be kept at the bedside.
Diphtheria drugs include erythromycin and penicillin G. Antibiotics must be administered as soon as feasible in order to eradicate the organism. This serves to restrict the amount of poison released into the system, accelerates the patient’s recovery, and prevents the illness from spreading to close contacts. In addition, linezolid or vancomycin can be used to treat antibiotic resistance.
Vaccination
Vaccination is the most important step in disease prevention. Parents should be educated on the need of routine immunization for illness prevention. In the event of a missed vaccination schedule or misplaced immunization records, parents should contact their primary care practitioner promptly and report the situation. Because diphtheria immunity fades with time, a booster dose of vaccine is important in the general population as well.
The importance of vaccines must be made known to the population. In the event of encounter with a suspected case, the individual must call a health care professional promptly to seek adequate consultation. Similarly, a diphtheria patient should be made aware of the significance of isolation and limiting contact with the general public unless cleared to do so by a healthcare practitioner.
Close contacts who have recently been exposed to diphtheria should be closely monitored for any respiratory or cutaneous symptoms. Patients should be isolated for 7 to 10 days, swabs should be obtained for culture, and erythromycin should be used. If the individual’s immunization status is uncertain, a booster dose of diphtheria toxoid should be administered as well.
Diphtheria vaccines are in the form of toxoids. Toxoid is a denatured protein (a bacterial toxin) that has an intact receptor binding site and the potential to produce antibodies. Diphtheria vaccination is typically administered in conjunction with tetanus and pertussis vaccines. The combined diphtheria vaccine comes in several forms, including DTaP (vaccination against diphtheria, tetanus, and pertussis), Tdap (vaccination against tetanus, diphtheria, and pertussis), DT (vaccination against diphtheria and tetanus), and td (vaccination against tetanus and diphtheria).