Pathophysiology
Clinical meaning
Lemierre syndrome (postanginal sepsis or necrobacillosis) is a rare but life-threatening condition characterized by oropharyngeal infection (typically pharyngitis or peritonsillar abscess) complicated by septic thrombophlebitis of the internal jugular vein (IJV) and metastatic septic emboli to distant organs, most commonly the lungs. The causative organism in the vast majority of cases is Fusobacterium necrophorum, an obligate anaerobic gram-negative bacillus that is part of the normal oropharyngeal flora. The pathogenesis follows a predictable sequence. An initial oropharyngeal infection (pharyngitis, tonsillitis, peritonsillar abscess, or dental infection) allows F. necrophorum to invade the pharyngeal mucosa and spread to the lateral pharyngeal space (parapharyngeal space). From there, the infection reaches the internal jugular vein through direct extension or via the tonsillar and peritonsillar veins. F. necrophorum produces several virulence factors including lipopolysaccharide endotoxin, leukocidin (which destroys white blood cells), hemagglutinin (which promotes platelet aggregation), and lipase. These factors damage the venous endothelium, activate the coagulation cascade, and lead to septic thrombophlebitis of the IJV. The infected thrombus in the IJV serves as a nidus for persistent bacteremia and releases septic emboli into the venous...