Lemierre’s syndrome is a rare but serious bacterial infection that often begins with a sore throat and progresses rapidly to a life-threatening systemic illness. It involves the formation of an infected blood clot in a major neck vein, which spreads the infection throughout the body. Prompt recognition is vital, as delayed diagnosis can lead to severe complications, including organ damage and sepsis.
The Causative Bacteria
The primary organism responsible for over 80% of Lemierre’s syndrome is Fusobacterium necrophorum, an anaerobic, Gram-negative bacteria. This bacterium is typically part of the normal flora residing in the mouth, throat, and gastrointestinal tract. When the throat’s mucosal lining is damaged, the organism can become pathogenic. The syndrome frequently begins as an upper respiratory tract infection, such as pharyngitis or tonsillitis, often in healthy adolescents and young adults.
The initial sore throat provides the entry point, allowing the bacteria to invade the deeper tissues of the neck. F. necrophorum possesses virulence factors that enable it to penetrate the mucosal barrier. This localized infection sets the stage for the severe systemic disease. Increased cases may be linked to reduced antibiotic use, allowing the infection to progress unchecked.
How the Infection Spreads
The transition to systemic illness involves the spread of bacteria into the lateral pharyngeal space of the neck. This area contains the internal jugular vein (IJV), which drains blood from the head and neck. Infection and inflammation surrounding the IJV cause septic thrombophlebitis—the formation of an infected blood clot within the vein.
Once the clot forms, the IJV continuously contaminates the bloodstream, leading to bacteremia. Fragments of this infected clot, called septic emboli, break off and travel through the circulatory system. These emboli lodge primarily in the lungs, the most common site of metastatic infection, affecting up to 90% of patients. Lung infection can cause pulmonary abscesses, pneumonia, or empyema.
Key Warning Signs
The clinical presentation follows a distinct progression after the initial throat illness. A patient may experience a sore throat that seems to improve, only to develop new, severe symptoms several days to a week later. The most common sign is a high, spiking fever accompanied by chills and rigors, indicating systemic infection.
A specific symptom is severe pain or tenderness on one side of the neck, often near the jaw angle, resulting from the thrombosed internal jugular vein. This neck pain may include stiffness or swelling. As the infection spreads, patients develop respiratory symptoms such as cough, chest pain, or difficulty breathing. The combination of a recent sore throat, persistent high fever, and new neck pain should raise immediate suspicion for this syndrome.
Confirmation and Recovery
Diagnosis requires clinical suspicion, laboratory confirmation, and imaging studies. Blood cultures are necessary to isolate the causative bacteria, F. necrophorum. Laboratories must be notified because the organism requires special anaerobic culture conditions. Elevated markers of systemic inflammation, such as C-reactive protein, are typically observed.
Imaging visualizes the infected blood clot and areas of metastatic infection. A contrast-enhanced CT scan of the neck is the standard method for identifying thrombophlebitis of the internal jugular vein. A chest CT scan is also performed to look for characteristic septic emboli, which often appear as multiple small nodules or abscesses in the lungs.
Standard treatment involves a prolonged course of intravenous antibiotic therapy, typically lasting three to six weeks. The regimen usually includes antibiotics like metronidazole and a beta-lactam antibiotic to cover the anaerobic Fusobacterium species. Supportive care addresses complications such as respiratory failure or septic shock. The use of anticoagulation medication for IJV thrombosis remains a subject of ongoing debate and is decided case-by-case.