<i>Trichomonas tenax</i> detected in pleural effusion fluid: A case report

<i>Trichomonas tenax</i> is predominant in dental caries and is commonly observed in patients with oral diseases; however, its presence in patients with pleural effusion remains rare. Pleural effusion can arise from various causes, including malignant tumors, tuberculosis and bacterial infections. Concurrent infections involving bacteria, fungi and <i>Trichomonas</i> are infrequent. This scenario is particularly rare in patients with tumor-associated <i>Trichomonas tenax</i> infection. The current study presents a case of <i>Trichomonas tenax</i> infection in a patient with a lung tumor. The patient, a 71-year-old male, experienced symptoms of chest tightness, shortness of breath, coughing and expectoration following surgery for a right lung tumor. The expectorated sputum was white and sticky, making coughing difficult. The patient had a history of a prior right lung tumor resection and was subsequently admitted to Heping Hospital Affiliated to Changzhi Medical College (Changzhi, China). Routine examination of the pleural effusion fluid revealed the presence of <i>Trichomonas tenax</i> under a wet-film microscope. Molecular sequencing confirmed that the isolate was <i>Trichomonas tenax</i>. This case highlights <i>Trichomonas tenax</i> as a potential opportunistic pathogen in patients with lung cancer, underscoring the need for heightened clinical awareness. This study offers valuable insights for the diagnosis and prevention of infectious diseases among patients with cancer in the future.