Pyopneumothorax Caused by Trichomonas tenax and Porphyromonas endodontalis Coinfection in a Patient with Previous Cerebral Infarction: A Case Report and Literature Review

BACKGROUND: Even with the advent of NGS and PCR diagnostic tools, cases of chest infections caused by Trichomonas are still very rare. Such pathogens are less likely to be considered by clinicians. These cases frequently involve the pleura and lead to pneumothorax, hydropneumothorax, or pyopneumothorax, making the disease severe. CASE PRESENTATION: A 69-year-old man diagnosed with cerebral infarction a year ago sought medical attention for right-sided pyopneumothorax and respiratory failure. The pathogen found in the pleural fluid was highly suspected to be Trichomonas tenax (T. tenax). Pleural fluid mNGS confirmed T. tenax and Porphyromonas endodontalis coinfection. Metronidazole combined with piperacillin tazobactam was administered to counteract infection. Simultaneously, closed chest drainage and thoracoscopic release of pleural adhesions were performed. The patient was cured, discharged from the hospital, and was in good condition after six months of follow-up. CONCLUSION: When chest infections occur in patients with poor oral hygiene and underlying diseases that may lead to aspiration, the identification of Trichomonas infection should be noted. Early confirmation of the diagnosis often requires mNGS and PCR. Metronidazole is essentially effective against Trichomonas, and medical thoracoscopy can be used to manage pleural conditions if necessary.