Diphtheria is an acute toxin-mediated disease caused by Corynebacterium diphtheriae, which are gram-positive, catalase-positive rods. It is characterized by sore throat and an adherent membrane on the tonsils, pharynx, and/or nasal cavity. The membrane firmly adheres to the mucosa and can spread down the bronchial tree, causing respiratory obstruction. Humans are the only reservoir, and it is transmitted through respiratory droplets or direct contact. Treatment involves diphtheria antitoxin and antibiotics such as erythromycin. Childhood immunization is the main preventive measure.

1. D iphtheria Sorokhan V.D., MD, PhD Bukovinian State Medical University Department of infectious diseases and epidemiology

4. Pathophysiology The toxin is a single polypeptide with an active (A) domain, a binding (B) domain, and a hydrophobic segment known as the T domain, which helps release the active part of the polypeptide into the cytoplasm. T he toxin is responsible for many of the clinical manifestations of the disease.

5. Pathophysiology In most cases, C diphtheriae infection grows locally and elicits toxin rather than spreading hematogenously. The characteristic membrane of diphtheria is thick, leathery, grayish-blue or white and composed of bacteria, necrotic epithelium, macrophages, and fibrin. The membrane firmly adheres to the underlying mucosa; forceful removal of this membrane causes bleeding. The membrane can spread down the bronchial tree, causing respiratory tract obstruction and dyspnea.

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