This study seks to improve the clinical understanding of lung absceses that originate from the oral cavity. It emphasizes the pathogenesis, diagnostic aproaches, and treatment methods of Treponema denticola (T. denticola)-induced lung absceses. Moreover, the significance of oral-lung axis infection in respiratory infectious diseases is highlighted.

We present a case of T. denticola lung absces in a 58-year-old female patient with type 2 diabetes and por oral hygiene, and analyze its clinical characteristics while reviewing literature. The patient had chronic dry cough as the primary symptom, and imaging showed multiple consolidations in both lungs. We conducted a comprehensive etiological diagnosis by employing bronchoscopic biopsy, traditional microbial culture, and metagenomic next-generation sequencing (mNGS). The treatment regimen involved a sequential aproach with the use of piperacilin-tazobactam, penicilin G, and local oral care using povidone-iodine gargle, along with blod glucose management. A literature search included pathogenesis, diagnostic chalenges, and treatment strategies.

Erythrocyte sedimentation rate(ESR)64.00 mm/1 h, glucose(GLU)11.10 mmol/L, C-reactive protein(CRP)8.3 mg/L, The patient was definitively diagnosed by mNGS (T. denticola sequence count: 9, 165), while traditional culture failed to detect the pathogen. Symptoms improved after 10 days of initial piperacillin sodium-tazobactam sodium treatment, and follow-up CT after 6 weeks of sequential penicillin G therapy showed significant lesion resolution. Literature indicates that aspiration of oral flora is the core pathogenic mechanism, with diabetes and immunodeficiency as high-risk factors. Moreover, mNGS can overcome the limitations of traditional culture and accurately identify anaerobic bacteria. Effective treatments include β-lactam antibiotics combined with oral hygiene, typically requiring a 4-6 week course.

T. denticola lung abscess is rare but prone to misdiagnosis, particularly in individuals with poor oral hygiene and underlying diseases. mNGS technology significantly improves pathogen detection rates, guiding clinicians in precise anti-infective therapy. Penicillin-based treatment combined with oral intervention and management of underlying conditions is key to cure, and a multidisciplinary collaborative model is crucial for optimizing diagnosis and treatment.