19M +fever/cough x 2wks. Exam: n/l except draining fluctuance on chest. CT: lung abscess adjacent to skin. Cx: Aspergillus nidulans. 6mos ago skin abscesses 2/2 Burkholderia. 1yr ago, pneumonia 2/2 Serratia. HIV(-). CBC nl. Test for most likely underlying immunodeficiency?
1/8) Answer: dihydrorhodamine test. Case of chronic granulomatous disease (CGD), one of the primary immunodeficiencies that can sometimes present in adulthood similar to common variable immunodeficiency (CVID), GATA 2 deficiency, hyper IgE syndrome (Job syndrome). #IDMedEd
2/8) GATA 2 deficiency was previously quizzed. Check it out again: . #IDMedEd #immunodeficiency
3/8) Main problem in CGD ✔️genetic mutation (X-linked or autosomal dominant) ➡️ deactivates NADPH ➡️ phagocytes fail to generate superoxide radicals/H2O2 ➡️ fails to generate proteases that kill 🌟 catalase (+) organisms. #IDMedEd #CGD
4/8) Why ⬆️ risk for catalase (+) organisms? Bacteria ✔️produce H2O2, catalase ✔️neutralizes H2O2. Bacterial H2O2 ➡️ used by the defective CGD phagocytes to its advantage & ✔️kills the bacteria. Thus, catalase (-) bacteria ➡️ +H2O2 ➡️ avoids infection in CGD patients. #IDMedEd
5/8) Recent studies show that above pathophysiology maybe an oversimplification. Catalase positivity not an essential component to establish infection. Exact pathophysiology remain to be elucidated. #IDMedEd
6/8) When to suspect? Recurrent bacterial/fungal infection (skin > lung) w/ mostly catalase +/unusual bugs. 📌💯Top 5: Aspergillus, Staph aureus, Burkholderia, Serratia, Nocardia. Others: BCG, Salmonella, NTM, TB. No risk✖️for viral infection. #IDMedEd
7/8) Dx: high index of suspicion, neutrophil function test. Test of choice: dihydrorhodamine (DHR) test + genetic testing. DHR now preferred over nitroblue tetrazolium (NBT) test. Both tests rely on color changes as a result of superoxide generation. #IDMedEd
8/8) Tx: early diagnosis, aggressive management of infection, antimicrobial prophylaxis (longterm sulfa/TMP, itraconazole), +/- interferon gamma. #IDMedEd
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