Molecular microbiological investigation of post-vaccination bacille Calmette-Guérin infection in Iranian patients

Abstract

Background: The World Health Organization (WHO) has called for closer monitoring of bacille Calmette-Guérin (BCG) complications with specific efforts to distinguish BCG infection from tuberculosis.

Objectives: To detect the presence of BCG infection using clinical and microbiological approaches.

Study design: Between 2006 and 2008, 32 cases, including 30 children with suspected BCG-related complications and two adults with local skin infections, were referred to our laboratory. The definitive identification of the isolates was based on phenotypic and molecular testing. The genotype profile of the isolates was determined to evaluate the relatedness of the cases.

Results: Molecular microbiological results confirmed the presence of infection due to Mycobacterium bovis BCG in 11 patients, of whom 9 were aged 2 months to 6 years and 2 were aged > 40 years. Molecular fingerprinting revealed that all isolates were genetically related to each other and to M. bovis BCG Pasteur 1173P2.

Conclusion: A high incidence of adverse reactions to the BCG vaccine in the population studied clearly points to the need for a thorough study on the issue. We hope our study will be viewed as an evidence-based document for more precise risk-benefit evaluation of BCG immunisation in immunocompromised patients.