International Journal of Mycobacteriology (Jan 2015)
Molecular analysis of Mycobacterium isolates from patients with BCG-induced lymphadenitis
Abstract
The Bacillus Calmette-Guérin (BCG) vaccine is administered to all newborns within the first days of life for the prevention of tuberculosis (TB) in many of the developing countries, including Iran. BCG vaccine is prepared from a special strain of Mycobacterium bovis. This vaccine is safe, but local and systemic side effects are associated with BCG vaccine. Severe adverse effects of BCG vaccination are extremely rare in immunocompetent children, but lymphadenitis, which is the most common side effect of BCG vaccination in children, is seen with high frequency in Iran. Different studies have shown that the vaccine strain and its genetic variations are important in inducing these side effects. Therefore, in this study, the aim is to analyze the genetic characterizations of vaccine strains used in Iran. Methods: The samples were collected from infants showing lymphadenitis induced by BCG vaccination. After acid-fast staining and culture of samples on Lowenstein–Jensen medium, DNA was extracted from samples using Phenol–chloroform method. Using primer for 16sRNA gene, the genus of the isolates was characterized. Then using RD1, RD14 and DU1 primers and followed by the next step using RD9, RD4 Deleted, RD4 Present and RD1 Deleted primers, the species and strains of the isolates were characterized. Results: All 30 samples of acid-fast bacilli that were isolated from infants with BCG complications confirmed as Mycobacterium genus using 16sRNA PCR and using RD1, RD14, DU1, RD9, RD4 Deleted, RD4 Present and RD1 Deleted primers confirmed that all isolates were M. bovis BCG strain Pasteur. Conclusion: As all of the strains isolated from the patients were confirmed as M. bovis BCG strain Pasteur, the other possible factors causing BCG complications, including BCG overdose, faulty intradermal technique, and disturbance of cellular immunity, must be considered.
