Does the BCG vaccine have different effects on strains of tuberculosis?

Abstract

Summary Several explanations have been suggested concerning the variety in bacille Calmette–Guerin (BCG) vaccine efficacy on strains of Mycobacterium tuberculosis (Mtb). This study aimed to compare the effect of BCG vaccination history in the prevention of the occurrence of Mtb-Beijing and non-Beijing strains. In this cross-sectional study, 64 patients with pulmonary tuberculosis (TB) were recruited from the Iranian border provinces (North West and West). Isolates were subjected to restriction fragment length polymorphism (RFLP) analysis, using the insertion sequence IS6110 as a probe (IS6110 RFLP) and drug susceptibility testing using the proportion method. Samples were analyzed with Gel Compare II 6.6 and spss version 18. The mean age [standard deviation (SD)] of the patients was 54·4 (SD = 17·0). Overall, 49 cases (76·56%) had no BCG vaccination scar. The prevalence of Beijing strains was 9·38% and drug resistance proportion among the isolates was 14·1% (nine cases). There was a significant relationship between Beijing strains and tuberculosis (TB)-drug resistance in isolates (χ2 = 26·29, P < 0·001). There was also a strong association between vaccination history and Beijing strains (χ2 = 13·23, P = 0·002). Also, a statistical relationship was observed between Beijing strains and drug-resistant TB among patients with a history of vaccination (χ2 = 7·47, P = 0·002). This association was not maintained in the unvaccinated group (P = 0·102). These findings confirm the claim that the vaccine has different effects on different subspecies of tuberculosis. The cause of the high probability of drug resistance in patients with Beijing-TB and vaccination history requires further investigation with a higher sample size.

Correlation between innate and adaptive immunity response in TB children post BCG vaccination. Is it effective or not?: Cross-sectional study

“…The scar formation is influenced by the type and strain of vaccine, age of administration, technique of injection, genetic factors, nutritional status, poor cold chain management, simultaneous oral polio vaccine administration, exposure to environmental Mycobacterium, gestational age at birth, and different subspecies [ [38] , [39] , [40] , [41] ]. The subjects with scar are about 68.1%, most of them female, under 6 years old, with undernutrition, and part of them with a positive history of TB contact.…”

Multiplexed Strain Phenotyping Defines Consequences of Genetic Diversity in Mycobacterium tuberculosis for Infection and Vaccination Outcomes

“…BCG is a live, attenuated strain of Mycobacterium bovis whose protective efficacy is both incomplete and variable ( 38 ). One contribution to the variable efficacy of BCG is thought to be M. tuberculosis strain diversity, and some, but not all, studies have found that BCG has reduced efficacy against infection by mL2 strains ( 8 , 36 , 39 – 42 ). However, this has been difficult to assess in human population studies due to host and environmental confounders.…”

The Emergence of Novel Spoligotypes of Highly Drug-Resistant Mycobacterium tuberculosis Isolates in Fujian, China

“…The second explanation is based on accumulated evidence that suggests that the Beijing genotype has achieved successful global dominance by eluding BCG vaccination-based protection. 25 Although China has implemented BCG vaccination of newborns since the 1980s, the predominance of the Beijing genotype in young individuals may be partly explained by ineffective BCG vaccine protection against this virulent genotype that has allowed this genotype to outcompete other genotypes in younger hosts.…”