A Pulmonary Abscess Caused by Porphyromonas gingivalis Infection: A Case Report and Literature Review.

Lung abscess is a common disease in respiratory medicine, which is a suppurative lesion caused by various pathogens, and microbiological examination is crucial for the treatment of lung abscess. Due to the widespread use of antibiotics, it is difficult to obtain reliable microbiological evidence through routine tests. There are various pathogens present in the oral cavity, and periodontitis is a risk factor for the formation of lung abscess. Enhancing understanding of lung abscesses caused by Porphyromonas gingivalis and the importance of accurately interpreting NGS reports. This article will present a case report of a lung abscess related to oral bacteria (Porphyromonas gingivalis). The patient was initially treated with empirical anti-infective therapy, which was ineffective, and despite multiple sputum cultures and bronchoalveolar lavage fluid analysis using metagenomic next-generation sequencing (mNGS), the pathogen could not be identified clearly. However, based on the significant presence of oral bacteria in the NGS of the bronchoalveolar lavage fluid, which guided the examination to discover periodontitis. Subsequently, a percutaneous lung tissue biopsy was performed for NGS testing, which further suggested Porphyromonas gingivalis as the pathogenic bacterium. This article summarizes the clinical manifestations, imaging findings, and characteristics of the pathogenic microorganisms in this case of lung abscess, reviews relevant literature to enhance the understanding of lung abscess caused by Porphyromonas gingivalis. It also confirms the importance of careful analysis of background bacteria in bronchoalveolar lavage fluid NGS based on objective risk factors, and highlights that combining patient clinical features with multisample NGS examination can promptly clarify the microbiology.