Lemierre's Syndrome - Pathophysiology

Pathophysiology

Lemierre's syndrome is initiated by an infection of the head and neck region. Usually this infection is a pharyngitis (which occurred in 87.1% of patients as reported by a literature review), but it can also be initiated by an otitis, a mastoiditis, a sinusitis or a parotitis.

During the primary infection, F. necrophorum colonizes the infection site and the infection spreads to the parapharyngeal space. The bacteria then invade the peritonsillar blood vessels where they can spread to the internal jugular vein. In this vein, the bacteria cause the formation of a thrombus containing these bacteria. Furthermore, the internal jugular vein becomes inflamed. This septic thrombophlebitis can give rise to septic microemboli that disseminate to other parts of the body where they can form abscesses and septic infarctions. The first capillaries that the emboli encounter where they can nestle themselves are the pulmonary capillaries. As a consequence, the most frequently involved site of septic metastases are the lungs, followed by the joints (knee, hip, sternoclavicular joint, shoulder and elbow). In the lungs, the bacteria cause abscesses, nodulary and cavitary lesions. Pleural effusion is often present. Other sites involved in septic metastasis and abscess formation are the muscles and soft tissues, liver, spleen, kidneys and nervous system (intracranial abscesses, meningitis).

Production of bacterial toxins such as lipopolysaccharide leads to secretion of cytokines by white blood cells which then both lead to symptoms of sepsis. F. necrophorum produces hemagglutinin which causes platelet aggregation that can lead to diffuse intravascular coagulation and thrombocytopenia.