Dialister pneumosintes bacteremia associated with sinusitis and suspected meningitis: a case report and literature review.

backgroundDialister pneumosintes(D. pneumosintes) is a slow-growing, obligate anaerobic Gram-negative bacillus commonly found in the oral cavity, nasopharynx, gastrointestinal tract, and vaginal microbiota. Although typically associated with periodontal disease, D. pneumosintes has rarely been implicated in bloodstream infections and, to date, has not been reported as a causative agent of meningitis. This case report describes D. pneumosintes bacteremia complicated by meningitis, highlighting the diagnostic challenges associated with fastidious anaerobes and the role of advanced microbiological techniques, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene analysis, in accurate pathogen identification. CASE PRESENTATION: A 65-year-old woman presented with fever, dysarthria, and posterior neck pain. Clinical examination revealed altered consciousness, restricted neck mobility, bilateral eyelid edema, and nasal speech. Laboratory findings indicated hypokalemia and metabolic alkalosis. Imaging studies revealed marked mucosal thickening and fluid accumulation in the paranasal sinuses, suggesting sinusitis with possible extension to the middle ear. Lumbar puncture before initiation of antibiotic therapy revealed neutrophilic pleocytosis consistent with acute bacterial meningitis. Blood cultures grew Staphylococcus hominis and an unidentified anaerobic Gram-negative bacillus, which was later identified as D. pneumosintes using MALDI-TOF MS. Empirical antibiotic therapy with ceftriaxone, vancomycin, ampicillin, and corticosteroids was initiated. Persistent fever prompted endoscopic sinus surgery on hospital day 5, with intraoperative cultures yielding Staphylococcus aureus and revealing a benign nasal papilloma. Neurological symptoms improved postoperatively. The patient completed 14 days of intravenous antibiotic treatment and was ultimately discharged on day 45.

conclusionThis is an exceptionally rare case of D. pneumosintes bacteremia complicated by meningitis. Given its propensity to originate from odontogenic or sinonasal infections and cause hematogenous dissemination with invasive complications such as abscesses or septic thrombosis, prompt identification is essential. When detected, clinicians should initiate a comprehensive systemic evaluation and consider surgical intervention as part of the treatment strategy. As advanced diagnostic tools such as MALDI-TOF MS and 16S rRNA gene sequencing become more widely available, increased clinical recognition of D. pneumosintes as a potential pathogen in severe anaerobic infections is warranted. CLINICAL TRIAL NUMBER: Not applicable.