AUTHOR=Yu Fangyu , Zhang Xiaojing , Li Yujiao , Gai Wei , Zheng Yafeng , Cai Xudong TITLE=Severe pneumonia with empyema due to multiple anaerobic infections: case report and literature review JOURNAL=Frontiers in Medicine VOLUME=Volume 11 - 2024 YEAR=2024 URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1435823 DOI=10.3389/fmed.2024.1435823 ISSN=2296-858X ABSTRACT=Background: Cases of severe pneumonia complicated by empyema due to normal anaerobic flora from the oral cavity are infrequent. Diagnosing anaerobic infections through conventional microbiological test (CMT) is often challenging.Case presentation: This study describes the case of a 67-year-old man, bedridden long-term, who developed severe pneumonia with empyema caused by multiple anaerobic bacterial infections. The patient was hospitalized with a five-day history of cough, sputum and fever, accompanied by a twoday history of dyspnea. Despite CMT, the specific etiology remained elusive. However, metagenomic next-generation sequencing (mNGS) identified various anaerobic bacteria in bronchoalveolar lavage fluid (BALF), blood and pleural effusion. The patient was diagnosed with a polymicrobial infection involving multiple anaerobic bacteria. Following treatment with metronidazole and moxifloxacin, the patient's pulmonary symptoms improved.mNGS serves as a valuable adjunctive tool for diagnosting and managing patients whose etiology remains unidentified following CMT.