Diphtheria is a bacterial infection caused by *Corynebacterium diphtheriae*, characterized morphologically by gram-positive club-shaped bacilli with metachromatic granules arranged in V- or L-shaped palisades and pathophysiologically by the secretion of an exotoxin encoded by a beta-prophage. This exotoxin induces ADP ribosylation of elongation factor 2 (EF-2), thereby inhibiting protein synthesis and causing cell death, which manifests clinically as pseudomembranous pharyngitis that bleeds upon removal. The disease represents a classic mechanism where localized mucosal infection disseminates via the lymphatic system to cause systemic sequelae such as myocarditis and acute tubular necrosis in non-immunized or endemic populations.
Diphtheria is a bacterial infection caused by *Corynebacterium diphtheriae*, characterized morphologically by gram-positive club-shaped bacilli with metachromatic granules arranged in V- or L-shaped …