Chronic granulomatous disease (CGD) results from NADPH oxidase deficiency. Patients suffer from recurrent infections with catalase-positive organisms because:

• A Opsonization with IgG is impaired, preventing phagocytosis
• B Without NADPH oxidase-derived H2O2, catalase-positive bacteria destroy even the small H2O2 they produce ✓
• C Complement C3b deposition is deficient, impairing recognition
• D Neutrophils cannot perform chemotaxis toward infected tissues

Explanation

In CGD, neutrophils cannot generate superoxide and H2O2 via the respiratory burst. Catalase-negative bacteria (e.g., streptococci) produce their own H2O2 that leaks into the phagolysosome; in CGD neutrophils this H2O2 is still useful. However, catalase-positive organisms (Staph aureus, Aspergillus, Klebsiella) destroy their own H2O2 with catalase, leaving the phagocyte no reactive oxygen species to kill the microbe. Opsonization and complement are intact in CGD.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.