Severe Necrotizing Community-Acquired Pneumonia and Bilateral Empyema in an Immunocompetent Patient due to Fusobacterium necrophorum.

Necrotizing pneumonia and empyema caused by Fusobacterium necrophorum are uncommon. The classical presentation of Lemierre's syndrome, characterized by pharyngotonsillitis and internal jugular vein thrombosis, is not always observed, and incomplete and atypical variants can cause diagnostic uncertainty and delay in treatment. We describe the case of a previously healthy 22-year-old male athlete who developed severe necrotizing community-acquired pneumonia, bilateral empyema, and acute hypoxemic respiratory failure due to F. necrophorum infection, without the typical vascular thrombosis associated with Lemierre's syndrome. Blood cultures and broad-range PCR analysis of the empyema fluid confirmed the presence of F. necrophorum. The patient was initially treated with piperacillin-tazobactam, intravenous corticosteroids, and bilateral chest tube placement for empyema management. Treatment with piperacillin-tazobactam was complicated by drug-induced liver injury requiring antimicrobial change to ampicillin-sulbactam. The patient was discharged on oral amoxicillin-clavulanic acid and completed a total of 5 weeks of antimicrobial therapy with complete recovery. This case highlights the importance of considering F. necrophorum as a potential pathogen in necrotizing community-acquired pneumonia, even in immunocompetent adults, and in the absence of classic Lemierre's syndrome features. Furthermore, its novelty and contribution to the medical literature stem from the patient's presentation with bilateral empyema requiring bilateral drains, the combined blood culture and pleural fluid 16S confirmation of F. necrophorum infection, and the preceding steroid exposure that contributed to clinical deterioration.