Diphtheria is an acute toxin-mediated infection of the upper respiratory tract or skin caused by toxin-producing Corynebacterium diphtheriae

-Corynebacteria are gram-positive, non-spore forming, club-shaped rods with a beaded appearance on Gram stain

-it has largely been eradicated in developed nations through widespread vaccination

-It is transmitted from person to person through respiratory secretions or skin lesions. 

Symptoms & signs

Respiratory diphtheria: fever, sore throat with a gray pseudomembrane, malaise, dysphagia, barking cough, stridor, hoarseness, swollen cervical lymph nodes, brawny edema of the neck (bull neck), tachycardia out of proportion to fever

Cutaneous diphtheria: Ulcerative lesions  

Diphtheritic myocarditis:  rapid, thready pulse, arrhythmias, circulatory collapse

Diphtheritic neuropathy: Paralysis of the muscles of the soft palate and pharynx, Peripheral neuritis

Diagnosis 

-Diagnosis is clinical

-Diagnosis is confirmed by isolation of bacteria by culture of a nasopharyngeal swab

-Culture shows club-shaped gram-positive rods in clusters of parallel rays (palisades), in V or L shaped formations referred to as “Chinese characters.” 

-Laboratory must be notified of suspicion in advance

Treatment 

The treatment of choice is antitoxin

To be effective, diphtheria antitoxin should be administered within 48 hours 

Treatment includes antitoxin, antibiotics (Procaine penicillin, erythromycin) , and respiratory support as needed