Severe Polymicrobial Pneumonia With Septicemia After Interruption of Immunoglobulin Replacement in X-Linked Agammaglobulinemia: A Case Report.

BACKGROUND: X-linked agammaglobulinemia (XLA) is an inherited primary immunodeficiency characterized by impaired B-cell maturation, profound hypogammaglobulinemia, and susceptibility to recurrent bacterial infections. Lifelong immunoglobulin replacement therapy (IGRT) is essential to reduce infectious complications, but treatment interruptions may markedly increase infection risk. CASE PRESENTATION: An 18-year-old male with XLA discontinued regular intravenous immunoglobulin (IVIG) replacement for 12 months because of financial constraints. He presented with fever, productive cough, pleuritic chest pain, hypoxemia, leukocytosis, and elevated inflammatory markers. His serum IgG level was 98.10 mg/dL. Chest computed tomography showed consolidation of the right middle and lower lobes without cavitation or bronchiectasis. Blood cultures and molecular testing of respiratory specimens identified both Klebsiella pneumoniae and Streptococcus pneumoniae, supporting polymicrobial pneumonia with bloodstream infection. A pathogenic Bruton tyrosine kinase (BTK) c.1522G >A (p.Ala508Thr) variant was confirmed. Intravenous imipenem-cilastatin and levofloxacin were administered according to antimicrobial susceptibility results. After 5 days, fever and oxygen dependence persisted despite improvement in leukocytosis. Following consultation with the hematology department, IVIG was readministered at 400 mg/kg, followed within 48 h by defervescence, discontinuation of supplemental oxygen, and marked improvement in inflammatory markers. He was discharged on hospital day 14, resumed IVIG every 4 weeks, and had no significant residual pulmonary lesion on follow-up computed tomography 1 month later. CONCLUSION: This case highlights the consequences of interrupted immunoglobulin replacement in XLA and the importance of combining pathogen-directed antimicrobial therapy with restoration of humoral protection in severe infection. It also illustrates how financial barriers may compromise continuity of lifelong treatment.