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Open Access Highly Accessed Research article

Tuberculosis associated with Mycobacterium tuberculosis Beijing and non-Beijing genotypes: a clinical and immunological comparison

Yong-Jiang Sun1*, TK Lim2, Adrian Kheng Yeow Ong1, Benjamin Choon Heng Ho3, Geok Teng Seah4 and Nicholas I Paton1

Author Affiliations

1 Department of Infectious Diseases, Tan Tock Seng Hospital, Republic of Singapore

2 Department of Medicine, National University of Singapore, Republic of Singapore

3 Department of General Medicine, Tan Tock Seng Hospital, Republic of Singapore

4 Department of Microbiology, National University of Singapore, Republic of Singapore

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BMC Infectious Diseases 2006, 6:105  doi:10.1186/1471-2334-6-105

Published: 5 July 2006

Abstract

Background

The Mycobacterium tuberculosis Beijing genotype is biologically different from other genotypes. We aimed to clinically and immunologically compare human tuberculosis caused by Beijing and non-Beijing strains.

Methods

Pulmonary tuberculosis patients were prospectively enrolled and grouped by their M. tuberculosis genotypes. The clinical features, plasma cytokine levels, and cytokine gene expression levels in peripheral blood mononuclear cells (PBMC) were compared between the patients in Beijing and non-Beijing groups.

Results

Patients in the Beijing group were characterized by significantly lower frequency of fever (odds ratio, 0.12, p = 0.008) and pulmonary cavitation (odds ratio, 0.2, p = 0.049). Night sweats were also significantly less frequent by univariate analysis, and the duration of cough prior to diagnosis was longer in Beijing compared to non-Beijing groups (medians, 60 versus 30 days, p = 0.048). The plasma and gene expression levels of interferon (IFN) γ and interleukin (IL)-18 were similar in the two groups. However, patients in the non-Beijing group had significantly increased IL-4 gene expression (p = 0.018) and lower IFN-γ : IL-4 cDNA copy number ratios (p = 0.01).

Conclusion

Patients with tuberculosis caused by Beijing strains appear to be less symptomatic than those who have disease caused by other strains. Th1 immune responses are similar in patients infected with Beijing and non-Beijing strains, but non-Beijing strains activate more Th2 immune responses compared with Beijing strains, as evidenced by increased IL-4 expression.