Case Report: mNGS-negative

Background: Case description: A 73-year-old male patient with a history of chronic obstructive pulmonary disease (COPD), diabetes mellitus, hypertension, and cerebral infarction presented with abdominal pain and distension for 7 days and no bowel movement for 3 days. He was diagnosed with incomplete small bowel obstruction at an outside hospital and treated with fasting, enemas, meropenem, and methylprednisolone. He was subsequently transferred to our hospital due to acute lower respiratory tract infection. Chest radiography revealed bilateral diffuse infiltrates, and his condition rapidly deteriorated, requiring admission to the intensive care unit (ICU), endotracheal intubation, mechanical ventilation, and continuous renal replacement therapy (CRRT). Stool smear and retrospective sputum examination both identified larvae of Strongyloides stercoralis. However, mNGS of sputum and bronchoalveolar lavage fluid (BALF) obtained upon admission failed to detect any parasitic sequences. The patient was treated sequentially with albendazole and ivermectin, in combination with broad-spectrum antibacterial, antifungal, and antiviral therapy. He ultimately died on February 11, 2025, due to severe pneumonia, sepsis, and bone marrow suppression. Conclusion: For immunocompromised hosts with multiple risk factors, particularly those exposed to glucocorticoids, active parasitic microscopic examination of stool and respiratory secretions should be pursued when unexplained pulmonary infiltrates coexist with gastrointestinal symptoms, even in the setting of negative mNGS results, to avoid missed diagnosis.