Multidrug-resistant Eikenella corrodens causing maxillary osteomyelitis with sequestrum and oronasal fistula: a rare case and literature review

Eikenella corrodens is a commensal organism of the oral and upper respiratory tract and is only rarely implicated in osteomyelitis. Maxillary involvement is considered uncommon, likely reflecting the rich vascularity of the maxilla. To our knowledge, maxillary osteomyelitis complicated by sequestrum and an oronasal fistula caused by multidrug-resistant (MDR) E. corrodens has not been previously reported. A 73-year-old man underwent extraction of a mobile maxillary tooth. One month later, he developed recurrent swelling at the extraction site, followed by purulent drainage from a gingival sinus tract and purulent discharge from the right nasal cavity. He received multiple empirical antibiotic courses without sustained improvement. Cone-beam CT revealed destructive changes of the anterior maxilla with sequestrum formation and communication with the nasal cavity. Biopsy excluded malignancy. Culture of purulent material yielded MDR E. corrodens (non-susceptible to at least one agent in ≥ 3 antimicrobial classes), susceptible to carbapenems, with intermediate activity of third-generation cephalosporins. Limited sequestrectomy combined with targeted antibiotic therapy resulted in complete recovery. This case highlights an unusual presentation of MDR E. corrodens–associated maxillary osteomyelitis with sequestrum and an oronasal fistula. It emphasizes the value of timely imaging and biopsy in persistent post-extraction infections and underscores the potential consequences of repeated empirical antibiotic use in dental practice.