From sore throat to facial vein thrombosis: a case of Fusobacterium necrophorum bacteraemia with a variant of Lemierre syndrome

A 34-year-old man presented with a 10-day history of malaise, sore neck and dysphagia with marked left cervical lymphadenopathy.

A contrast-enhanced computed tomography (CT) scan of the neck revealed bilateral tonsillitis (Figure 1). Due to a reported penicillin allergy from childhood, the details of which were unknown (PEN-FAST score 0), clindamycin—an acceptable alternative—was prescribed for 1 week before discharge. However, he was recalled to the hospital after blood cultures isolated a Gram-negative bacillus, later identified as Fusobacterium necrophorum (FN). Antimicrobial therapy was escalated to ceftriaxone and metronidazole to provide better empirical coverage in the setting of bacteraemia, given that FN is typically highly susceptible to metronidazole. Susceptibility testing was not routinely performed. His peak serum white blood cell count was 17.3x10^9/L and C-reactive protein was 290mg/L.

An interval scan performed 3 days later due to progressive neck swelling confirmed a filling defect within the left facial vein with no internal jugular vein (IJV) thrombus identified. The left temporal vein failed to opacify, raising suspicion of an associated thrombus (Figure 2).

Based on the absence of thrombus extension in the cerebral sinuses and the patient’s stable clinical course, the risks outweighed the benefits of therapeutic anticoagulation and thus was not initiated. He completed a 4-week course of antibiotics with complete symptom resolution and was discharged from clinic with no further complications.

View Figure 1–2.

Discussion

André Lemierre described Lemierre syndrome in 1936. It is typically characterised by thrombophlebitis of the IJV alongside bacteraemia caused by the anaerobic organism, FN, following an oropharyngeal infection.¹ It was common in the era before antibiotics; however, after the introduction of antibiotics, it became known as the “forgotten disease”.¹ Over recent decades, the incidence has been increasing, potentially due to increasing antimicrobial resistance associated with widespread antibiotic use for pharyngitis and awareness of this syndrome.^1–3 Although susceptibility testing is not routinely performed, clindamycin resistance in FN has been reported internationally, with rates ranging from 6.7 to 25%.⁴ Therefore, when alternative agents are used due to penicillin allergy, culture and sensitivity testing should be considered.

In New Zealand, epidemiological data are limited; however, globally, the incidence is estimated between 0.6 to 6 cases per million people per year.¹

Facial vein thrombosis represents an uncommon variant. The facial vein lacks valves and communicates directly with the ophthalmic veins, allowing retrograde spread into the cavernous sinus, increasing the risk for intracranial complications such as cavernous sinus thrombosis.⁵ While IJV thrombosis is well documented, isolated facial vein involvement is rare, leading to a delay in diagnosis due to its atypical presentation.⁵ The prognosis of facial vein thrombosis is less defined in comparison with IJV thrombosis.

Given its smaller calibre, spontaneous resolution may occur, and the role of anticoagulation remains controversial.^1,6,7 Some authors advocate for anticoagulation in all cases, while others recommend it only if thrombosis extends into the cerebral sinuses or there is no improvement with antibiotics.^7,8 The risk of septic embolisation remains a concern, highlighting the need for close monitoring.^2,9 The cornerstone of treatment remains appropriate antimicrobial therapy, with anticoagulation being individualised based on thrombus size, progression and response to antibiotics.⁹ Increased recognition is critical for timely diagnosis and intervention, preventing further complications and improving patient outcomes.³

In this case, the reported penicillin allergy led clinicians to use clindamycin as first-line therapy, a PEN-FAST score was not calculated and further details of the allergy were not obtained. Given that many reported penicillin allergies are not true Immunoglobulin E (IgE) mediated reactions, inaccurate labelling may limit optimal therapy. This case underscores the importance of structured allergy assessment, such as PEN-FAST scoring, to guide antibiotic selection and potentially avoid suboptimal alternatives.

Conclusion

This case highlights an atypical presentation of Lemierre syndrome, characterised by facial vein thrombosis rather than the typical IJV involvement. FN bacteraemia remains an important differential in patients with persistent tonsillitis and systemic features of infection. The rarity of facial vein thrombosis underscores the need for increased awareness to ensure timely diagnosis and management. Furthermore, this case emphasises the importance of structured assessment of reported penicillin allergies and demonstrates that antibiotic therapy alone may be curative in the absence of thrombus extension, despite the ongoing debate regarding the role of anticoagulation.