case_images: PMC11832390_01
case_images: Pathological results of renal tissue biopsy. Immunofluorescence: immunoglobulin IgA (A) and complement C3 (B) deposited in clumps and granules in the mesangial area and capillary loops of the glomerulus. Original magnification, x 400. (C) Electron microscopy: thickening of the basement membrane of glomerular capillary loops. Original magnification, x 3000. (D) Electron microscopy: electron dense deposition in the glomerular mesangial area. Original magnification, x 3000.
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case_images: F1
case_images: Pathological results showed that immunoglobulin IgA and complement C3 were deposited in clumps and granules in the mesangial area and capillary loops of the glomerulus (Figures 1A-D).
case_images: Pulmonary CT changes of this patient before and after Nocardia infection. (A) 12 days before admission (with no Nocardia infection): bronchiectasis without obvious pulmonary infection or pleural effusion. (B,C) On admission: bilateral bronchiectasis with pulmonary infection and bilateral pleural effusion. (D,E) On the 14th day of admission: worsening of bilateral pulmonary infections and bilateral pleural effusion, accompanied by left atelectasis. (F,G) 12 days after linezolid combined with TMP-SMZ treatment: bilateral pulmonary infection improved significantly, with a small amount of left pleural effusion. (H,I) 2 months after discharge: bronchiectasis with no obvious pulmonary infection and pleural effusion.
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case_images: F2
case_images: The patient was then diagnosed with "IgA nephropathy," but he refused treatment. 12 days before admission, after pulmonary computer tomography (CT) examination to rule out pulmonary infection and other potential infections (Figure 2A), the patient was treated with prednisone 30 mg/day orally due to increased proteinuria and progressive lower limb edema. Pulmonary CT results showed bronchiectasis with scattered infections, emphysema, and a small amount of bilateral pleural effusion (Figures 2B, C). Pulmonary CT results showed worsening of bilateral pulmonary infections and pleural effusion, accompanied by left atelectasis (Figures 2D, E). After 12 days of linezolid combined with TMP-SMZ treatment, pulmonary CT showed a significant improvement in pulmonary infection compared to before, only with a small amount of pleural effusion on the left side (Figures 2F, G), and the laboratory examination results showed WBC 4.01 x 109/L, neutrophils 74%,lymphocyte 18%,CRP 6.4 mg/L, and procalcitonin 0.35 ng/L. After a 2-month follow-up after discharge, except for occasional cough, the patient had no chest tightness, sputum or fever, and pulmonary CT showed no obvious infection or pleural effusion (Figures 2H, I).
case_images: Bacterial culture of bronchoalveolar lavage fluid and lip ulcers in patient. (A) Colonies of N. otitidiscaviarum cultured for 2 days. (B) Colonies of N. otitidiscaviarum cultured for 5 days. (C) Colony morphology of N. otitidiscaviarum. (D)
  N. otitidiscaviarum by Gram staining. (E)
  N. otitidiscaviarum by weak acid-fast staining. (F) Lip ulcers in patient (This image was obtained with the patient's informed consent).
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case_images: F3
case_images: In addition, The BALF culture results showed that pin-sized white colonies could be seen after 2 days, but it was difficult to identify the bacteria species (Figure 3A). Large, dry, white colonies were observed after 5 days (Figures 3B, C), which were Gram staining positive and weak acid-fast staining positive (Figures 3D, E), indicating Nocardia infection, a bacterium widely present in soil and dust. TMP-SMZ, the patient's symptoms of chest distress, cough, expectoration and fever were significantly improved, the tongue tip ulcer disappeared, and the lip skin ulcer gradually improved (Figure 3F). The patient's arterial oxygen saturation increased to over 98%, and the above-mentioned central nervous system symptoms disappeared.
case_images: Timeline of key events. IgAN, IgA nephropathy; TMP-SMZ, trimethoprim-sulfamethoxazole; BALF, bronchoalveolar lavage fluid; MIC, minimum inhibitory concentration.
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case_images: F4
case_images: After 42 days of hospitalization, the patient was discharged and continued to receive long-term oral treatment with linezolid at a dose of 0.6 g/day (The timeline of key events is shown in Figure 4).