Unusual fungal infection of the spine: A case report of Acremonium-induced vertebral osteomyelitis

Background: Fungal vertebral osteomyelitis (VO) is a rare disease, typically caused by Aspergillus or Candida spp. Acremonium spp., especially in the spine, is uncommon. While classically affecting immuno-compromised patients, cases in immuno-competent hosts are increasingly reported. Diagnosis relies on beta D-glucan, MRI and galactomannan assays, with voriconazole as preferred therapy. Case report: We report a rare case of fungal osteomyelitis in a 33-year-old immunocompetent adult male, with complaints of gradually progressing back pain accompanied by pain in the right leg for three months. Over the past year, this patient underwent L5-S1 laminectomy for disc radiculopathy after failed conservative treatment to resolve symptoms of left leg numbness. Magnetic Resonance Imaging showed discitis at surgical site without an abscess. After six weeks, a repeat scan revealed disease progression with an abscess and a new disc protrusion. Transforaminal lumbar interbody fusion (TLIF) with posterior instrumentation and fusion (PSIF) was performed, and fungal smears showed septate hyphae. Beta D-glucan was 99 pg/mL and galactomannan was 0.1 ODI. Cultures later yielded Acremonium spp. and voriconazole was started empirically. Results: This case highlights three critical points being, fungal VO must be considered in refractory spinal infections; Acremonium can infect immunocompetent hosts; and voriconazole shows efficacy against this organism. The rising incidence of nosocomial fungal infections warrants increased suspicion for atypical pathogens, even without classic risk factors. Tests like galactomannan and beta-D-glucan, although non-specific, in addition to PCR can aid diagnosis when cultures are pending. While amphotericin B remains first-line for many systemic mycoses, voriconazole's safety profile makes it preferable for long-term treatment. Conclusion: This case will emphasize the rarity of Acremonium as a causative agent for osteomyelitis and discuss the importance of an accurate, quick diagnosis and treatment plan for similar cases. In addition, further studies should be conducted regarding similar case presentations.