• Opportunist lung infections
• Rare lung diseases

A 38-year-old woman presented with a 1-month history of progressive cough and phlegm. She was an office worker. She denied the presence of comorbidities including diabetes, renal disease, malignancy and acquired immune deficiency syndrome. She underwent chest CT scan (figure 1A) 2 weeks before admission, having been taking moxifloxacin treatment for 12 days without improvement in symptoms. A repeat CT scan at admission showed significant progression of the lung lesions compared with previous imaging (figure 1B). Sputum culture was negative. Laboratory investigations revealed NK cells, CD4+, CD8+ lymphocytes and the CD4+/CD8+ lymphocytes ratio, serum interferon-γ, TNF-α, immunoglobulins (IgG, IgA and IgM), and complement components 3 and 4 detections were all in the normal range. A bronchoscopy showed mucoid impactions completely obstructed the anterior basal segment of the right lower lobe (figure 1C). Radial endobronchial ultrasound (EBUS) was used to detect the lesion in the bronchial lumen (figure 1D), and bronchoalveolar lavage (BAL) was performed. The cultured BAL fluid (BALF) stained with lactophenol cotton blue (figure 2A) and Gram staining (figure 2B) was positive. The metagenomic next-generation sequencing (mNGS) showed a high abundance and sequence number of Trichoderma longibrachiatum in the BALF. The patient was then treated with intravenous and oral sequential voriconazole regimen. Her symptoms improved gradually, and the lung lesion on imaging showed slight improvement after 1 month of treatment.

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Figure 1

(A) Chest CT performed 2 weeks before admission. (B) Chest CT showing progressive obstructive pneumonia in anterior basal segment of right lower lobe. (C) Bronchoscopy showing the bronchial lumen was completely obstructed by mucoid impactions (white arrow). (D) Endobronchial ultrasound showing the lesion in the bronchial lumen (white arrow).

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Figure 2

(A) Microscopic examination of cultured bronchoalveolar lavage fluid stained with lactophenol cotton blue. (B) Gram staining showing hyaline septate hyphae with short branches.

As a fungus belonging to the genus Trichoderma, T. longibrachiatum usually exists in humid soil and decaying wood, and is commonly not considered a pathogen in healthy individuals. It has been reported to have the ability to cause invasive infections in immunocompromised hosts.1 The mortality from T. longibrachiatum infection was as high as 53%.1 The only identified potential risk factor for T. longibrachiatum infection in our patient was that she had a history of close contact with a pot of Epipremnum aureum, an indoor potted green plant, for more than 1 month before the onset of the disease. The T. longibrachiatum culture of the planting soil was positive.

Early diagnosis of T. longibrachiatum is important because the disease has high mortality without treatment, delayed treatment or improper treatment.1 The clinical presentations of T. longibrachiatum infection are non-specific.1 Nowadays, mNGS has shown good application value for detecting complex and rare pathogen infections.2

T. longibrachiatum is considered a fungus refractory to treatment.3 Reportedly, it had a low minimal inhibitory concentration value to voriconazole in vitro drug sensitivity tests.1 3 Voriconazole alone or combined with amphotericin B is reported as preferred antifungal treatment of T. longibrachiatum.2

Our case is unusual because all previously reported patients were immunocompromised but, there was no evidence of immunosuppression in our patient. Furthermore, imaging reported previously were multiple nodules with or without halo and air-crescent signs, dense focal consolidations, cavitation, pleural effusion and pneumothorax. Here, imaging showed only focal postobstructive consolidation. Summarily, we report a novel case of pulmonary T. longibrachiatum infection in an immunocompetent individual and identification using radial EBUS with mNGS in the context of focal consolidation.