A 10-month-old male infant presents with recurrent bacterial infections (Staphylococcus aureus and Klebsiella), aphthous ulcers, and a skin abscess since 3 months of age. NBT (nitroblue tetrazolium) test is negative (no reduction). Flow cytometry shows normal B and T lymphocyte counts and normal neutrophil count. Which is the MOST LIKELY diagnosis?
- A Chronic granulomatous disease (CGD) due to NADPH oxidase deficiency ✓
- B X-linked agammaglobulinemia (Bruton's disease)
- C Leukocyte adhesion deficiency type I (LAD-I)
- D Common variable immunodeficiency (CVID)
Explanation
Chronic granulomatous disease (CGD) is an NADPH oxidase deficiency causing failure of the respiratory burst in neutrophils and macrophages. Despite normal neutrophil count, the cells cannot kill catalase-positive organisms (S. aureus, Aspergillus, Klebsiella, Salmonella, Serratia). The NBT test is the classic screening test—CGD neutrophils fail to reduce NBT (remain yellow), giving a negative result. XLA presents with absent B cells and recurrent pyogenic infections after 6 months. LAD-I presents with delayed umbilical cord separation and markedly elevated WBC counts. CVID typically presents in adolescents/young adults with low immunoglobulin levels.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.