Diphtheria

Diphtheria is an illness caused by toxigenic strains of Corynebacterium diphtheriae . It is endemic in many areas of the world and still occurs sporadically in the US.

Important sites of infection are the respiratory mucosa (respiratory diphtheria) and the skin (cutaneous diphtheria). Rarely, the mucosa of the eye, ear, or genitals may be affected. The incubation period is typically 2 to 7 days, occasionally longer.

Early intervention by administering antitoxin is key to preventing systemic manifestations of the disease, which can include respiratory and neurologic symptoms, cardiovascular collapse, and death.

Prompt administration of antitoxin is necessary to enable it to bind to and deactivate the free toxin in serum. Antitoxin cannot deactivate toxin once it has entered cells, which is signaled by the presence of mucocutaneous symptoms.

Patients with respiratory diphtheria are placed in respiratory isolation (masks and standard measures such as hand-washing), and those with cutaneous diphtheria are placed in contact isolation (gloves and gowns), until cultures taken after cessation of therapy are negative.

Asymptomatic carriers play an important role in disease transmission.

Respiratory diphtheria is an upper-respiratory tract illness characterized by sore throat, low-grade fever, and an adherent pseudomembrane that can cover the tonsils and the mucosa of the pharynx, larynx, and nose. Occasionally, the mucosa of the eyes, ears, or genitals may also be affected. It is caused by exotoxin-producing strains of Corynebacterium diphtheriae . Rarely, it may also be caused by other corynebacteria that produce diphtheria toxin, such as C ulcerans or C pseudotuberculosis . [1] American Academy of Pediatrics. Red Book Online: Diphtheria. 2015:325-329. http://aapredbook.aappublications.org/ (last accessed 18 March 2017). http://aapredbook.aappublications.org/content/current [2] Tejpratap SP, Tiwari MD. Manual for the surveillance of vaccine-preventable diseases (5th ed): Diphtheria. August 2011. http://www.cdc.gov (last accessed 18 March 2017). http://www.cdc.gov/vaccines/pubs/surv-manual/chpt01-dip.pdf The toxin causes tissue necrosis and formation of the pseudomembrane. It also causes the major complications of myocarditis and neuritis.

Cutaneous diphtheria may be caused by toxigenic or nontoxigenic strains of C diphtheriae and is usually a mild disease, causing cutaneous sores or shallow ulcers. Toxic complications are rare in cutaneous disease, occurring in 1% to 2% of infections with toxigenic strains. [2] Tejpratap SP, Tiwari MD. Manual for the surveillance of vaccine-preventable diseases (5th ed): Diphtheria. August 2011. http://www.cdc.gov (last accessed 18 March 2017). http://www.cdc.gov/vaccines/pubs/surv-manual/chpt01-dip.pdf [3] Lee PL. Lemos B, O'Brien SH, et al. Cutaneous diphtheroid infection and review of other cutaneous Gram-positive Bacillus infections. Cutis. 2007;79:371-377. http://www.ncbi.nlm.nih.gov/pubmed/17569399?tool=bestpractice.com