The Spectrum of Bacille Calmette-Guérin Diseases in Children-A Decade of Data from Neonatal Vaccination Settings

Isolated remote site musculoskeletal Mycobacterium bovis infections after BCG immunisation in immunocompetent children

The Bacillus Calmette–Guerin (BCG) vaccine, derived from wild-type Mycobacterium bovis, is administered in an attenuated form to prevent Mycobacterium tuberculous (MTB) infections in children residing in endemic regions. Since the introduction of the Singapore Tuberculosis Elimination Programme in 1997—specifying mandatory BCG-immunisation at birth—the incidence fell drastically to 32.6 per 100,000 population in 2021,1 with the paediatric population contributing 2.1% of infections.2

Granulomatous lymphadenitis in Taiwan: Unraveling infantile peak and Bacillus Calmette-Guérin lymphadenitis

BACKGROUND

Granulomatous lymphadenitis, a histopathological diagnosis, often indicates infections, such as those caused by mycobacterial and fungal agents.

METHODS

We conducted an analysis of 1098 granulomatous lymphadenitis cases, examining age distribution, lymph node locations, and laterality. Molecular detection of Bacillus Calmette-Guérin (BCG) was performed on archived formalin-fixed paraffin-embedded tissue specimens.

RESULTS

Our analysis revealed a bimodal age distribution, notably with a minor peak in infants. These infantile cases predominantly featured axillary involvement, frequently occurring on the left side. Positive rates of BCG identification decreased with age: <1 year, 71%; 1-2 year, 33%; 2-3 year, 13%; 3-4 year, 0%. Remarkably, only one of the 14 cases with molecularly confirmed BCG lymphadenitis had comments regarding BCG in the pathological report. Compared with patients born after 2016 (BCG at 5-8 months), those born before 2016 (BCG at birth) developed BCG lymphadenitis at a wider age range with right skewness (before 2016, 13 ± 11 months [range, 3-33 months] vs. after 2016, 10 ± 2 months [range, 8-13 months]). Four of the 14 BCG-positive cases had congenital heart disease. Seven patients received anti-tuberculosis drugs following surgical excision. No surgical complications were reported.

CONCLUSIONS

BCG lymphadenitis constitutes a distinctive minor peak within the spectrum of granulomatous lymphadenitis in Taiwan. Pathologists should consider the possibility of BCG infection, especially in cases of infantile axillary, supraclavicular, neck lymphadenopathies on the left side. Moreover, BCG administration at 5-8 months may reduce delayed-onset BCG lymphadenitis.

Adjuvants and Antigen-Delivery Systems for Subunit Vaccines against Tuberculosis

The only licensed vaccine against tuberculosis is BCG. However, BCG has failed to provide consistent protection against tuberculosis, especially pulmonary disease in adults. Furthermore, the use of BCG is contraindicated in immunocompromised subjects. The research towards the development of new vaccines against TB includes the use of Mycobacterium tuberculosis antigens as subunit vaccines. Such vaccines may be used either alone or in the prime-boost model in BCG-vaccinated people. However, the antigens for subunit vaccines require adjuvants and/or delivery systems to induce appropriate and protective immune responses against tuberculosis and other diseases. Articles published in this Special Issue have studied the pathogenesis of BCG in children and the use of BCG and recombinant BCG as potential vaccines against asthma. Furthermore, the use of different adjuvants and delivery systems in inducing the protective immune responses after immunization with subunit vaccines has been described.