Pneumonia Caused by Fusobacterium necrophorum: Is Lemierre Syndrome Still Current?

Fusobacterium necrophorum is a non-spore-forming gram-negative anaerobic bacillus that may be the causative agent of localized or severe systemic infections. Systemic infections due to F.necrophorum are known as Lemierre's syndrome, postanginal sepsis or necrobacillosis. The most common clinical course of severe infections in humans is a progressive illness from tonsillitis to septicemia in previously healthy young adults. A septic thrombophlebitis arising from the tonsillar veins and extending into the internal jugular vein leads to septicemia and septic emboli contributing to the development of necrotic abscesses especially in lungs and other tissues such as liver, bone and joints. In this case report, a previously healthy man with pneumonia and empyema due to F.necrophorum has been presented. A 22 year-old man suffering from sore throat for seven days was admitted to emergency department with ongoing fever and dysphagia for three days. On admission he was already taking amoxicillin-clavulanic acid and his complaints were relieved with continuation of therapy to a total of 10 days. However, five days after the cessation of treatment he developed productive cough, fever and generalized myalgia. On physical examination, there were crackles on right lower lung, and chest X-ray revealed pulmonary consolidation on the right middle lobe. Levofloxacin therapy was started based on the diagnosis of pneumonia. While polymorphonuclear leucocytes and intracellular gram-negative bacilli were seen in Gram stained sputum smear, sputum culture was reported as normal flora. Although the patient's status had started to improve with treatment, his condition deteriorated with development of fever and dyspnea. Chest X-ray revealed consolidation, pulmonary infiltrates, pleural effusion and air-fluid level on the right. Meropenem, clarithromycin and linezolid were initiated and a chest tube was inserted with the preliminary diagnosis of necrotizing pneumonia, empyema and type-1 respiratory failure. While there was no growth on bronchoalveolar lavage fluid culture, thoracentesis material inoculated into thioglycolate broth revealed turbidity. Further inoculation onto Schaedler agar which was incubated under anaerobic conditions, yielded growth of catalase negative, indol positive, gram-negative anaerobic bacilli identified as F.necrophorum by BBL Crystal system (Becton Dickinson, USA). The detailed history of the patient revealed that fish bone had stuck in his throat a week ago. Clarithromycin and linezolid were discontinued and he was recovered within six weeks of meropenem treatment. F.necrophorum infection should be considered in the differential diagnosis of persistent head and neck infections with rapidly progressive metastatic necrotic lesions especially in healthy young adults and clindamycin or metranidazol should be added to the treatment protocols.