Hemoptysis and High-Density Shadow of Both Lungs Combined with Elevated Serum G-Lipopolysaccharide Misdiagnosed as Bronchiectasis with Gram-Negative Bacterium Infection Ultimately Confirmed as Mycobacterium Iranicum Infection by CT-guided Percutaneous Lung Biopsy and Next Generation Sequencing (NGS): a Case Report and Literature Review.

Background: G-lipopolysaccharide, a component of the cell wall of Gram-negative bacteria, is called lipopolysaccharide. The detection of G-lipopolysaccharide can be used for the early diagnosis of infectious diseases, but some-times G-lipopolysaccharide provides limited help. We report a case of a patient with hemoptysis and high-density shadow of both lungs combined with elevated serum G-lipopolysaccharide which mimicked bronchiectasis with Gram-negative bacterium infection. It was ultimately confirmed as Mycobacterium iranicum infection by CT-guided percutaneous lung biopsy and next generation sequencing.

Methods: The chest computed tomography (CT) scan, CT-guided percutaneous lung biopsy, and NGS were performed for diagnosis and blood tests explored for the latent etiology.

Results: The chest CT scan showed a high-density shadow of both lungs, atelectasis of right middle lobe, multiple enlarged lymph nodes in mediastinum and right hilum. Pathology of CT-guided percutaneous lung biopsy indicated fibrous tissue proliferation and granulation tissue formation and some alveolar epithelial cells slightly proliferated with focal carbon powder deposition in alveolar sacs and spaces. The lung tissue NGS confirmed Mycobacterium iranicum infection.

Conclusions: Elevated serum G-lipopolysaccharide is not a specific index for infectious diseases. CT-guided percutaneous lung biopsy and lung tissue NGS has high specificity in pathogen detection of infectious diseases.