Post-Vaccination Disseminated Bacillus Calmette Guerin Infection Among Children in Southern Iran

Area of Science:

• Pediatric Infectious Diseases
• Vaccine-Preventable Diseases
• Molecular Diagnostics

Background:

• Disseminated Bacillus Calmette-Guérin (BCG) infection is a rare but severe complication following BCG vaccination, primarily affecting individuals with compromised immune systems.
• Early and precise diagnosis is critical for initiating effective anti-mycobacterial therapy to manage this life-threatening condition.

Purpose of the Study:

• To investigate the clinical characteristics and diagnostic confirmation of disseminated BCG infection in 34 children in southern Iran.
• To evaluate the utility of Polymerase Chain Reaction (PCR) in the rapid and specific diagnosis of Mycobacterium bovis BCG substrain infection.

Main Methods:

• Retrospective review of clinical and laboratory data from 34 children hospitalized with disseminated BCG infection between 1990 and 2007.
• Utilized an in-house Polymerase Chain Reaction (PCR) assay on pathology samples (bone marrow smears and tissue specimens) to confirm Mycobacterium bovis BCG substrain infection.

Main Results:

• Of 34 children, 21 had definite and 13 probable disseminated BCG infection; 91% were under two years old.
• Common findings included fever (91.2%), lymphadenopathy (76.5%), hepatosplenomegaly (73.5%), and stunted growth (61.8%).
• PCR achieved 100% positivity in bone marrow and 84.2% in tissue specimens. Fifty percent of patients had immunodeficiency, with an overall mortality rate of 58.8%.

Conclusions:

• Disseminated BCG infection is a critical differential diagnosis in young children presenting with fever, hepatosplenomegaly, and lymphadenopathy, especially with a history of BCG vaccination.
• Polymerase Chain Reaction (PCR) is a valuable tool for rapid and specific identification of Mycobacterium bovis BCG substrain, aiding in timely treatment decisions.