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Genotyping that differentiates between strains of Mycobacterium tuberculosis based on variations in the genome of the organism is a useful tool for molecular epidemiological studies of tuberculosis. In the present study, we identified a combination of five mycobacterial interspersed repetitive unit (MIRU) loci and three variable numbers of tandem repeats (VNTR) loci of M. tuberculosis that showed a discriminatory power comparable to that of the 15 to 24 loci-based typing proposed for international standardisation in analysing 210 paediatric isolates obtained from Chongqing, China.

Objective: To evaluate the application of spacer oligonucleotide typing (Spoligotyping) and mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) analysis in the molecular-epidemiological study of tuberculosis and to discuss the characteristics of pediatric Mycobacterium (M.) tuberculosis strains in Chongqing., Methods: M. tuberculosis strains isolated and typed by Spoligotyping and MIRU-VNTR respectively, from the children patients in Chongqing and to compare the results from both methods, epidemiologically., Results: By means of Spoligotyping, 210 clinical isolates were divided into 2 gene groups, displaying 44 genotypes. Among them, the biggest group was M. tuberculosis Beijing family, including 130 strains (61.90%), using the Spoligotyping. From the results of MIRU-VNTR, 24 loci showed different polymorphism and the HGI of different loci set (12 old loci, 15 basic loci and 24-loci set) increased accordingly. The subtle difference in HGI was originated from one locus ETR-B, which was included in the 24-locus system. The diversity of each loci and MIRU-VNTR set for non-Beijing genotype strains was higher than that of the Beijing genotype strains., Conclusion: In this study, it was preliminarily confirmed the existence of high polymorphism of M. tuberculosis while the Beijing Family was the main genotype and main prevalent strain in children of Chongqing area. Spoligotyping prior to 15-locus with ETR-B combination seemed more suitable for the massive epidemiological investigation of pediatric tuberculosis patients.

Objective: The aims of this study were to evaluate whether the presence of -2518A/G polymorphism in the distal regulatory region of the monocyte chemotactic protein-1 (MCP-1) was associated with tuberculosis (TB) in Chongqing Han population and to find whether it has a significant impact on the pediatric patient., Method: One hundred children [ < or = 15 years old, mean age (7.3+/-4.6) years, 53 male, 47 female] and one hundred adults [51 male, 49 female, age (44.6+/-13.5) years with TB] and 200 healthy controls of comparable age were screened for genotype by PCR-sequence-specific primer (SSP) method. MCP-1 levels in the sera were detected by ELISA., Result: (1) TB patients and controls showed different single nucleotide polymorphism (SNP) distribution patterns (58%, 36%). MCP-1 alleles -2518G was associated with increased TB susceptibility (P<0.01). (2) The -2518 GG genotypes was associated with increased TB susceptibility (32% in TB patients and 13% in non-TB controls respectively, P<0.01). (3) The odds of developing TB in genotypes GG were higher than those in homozygous AA, and the risk was higher in children than in adult (7.0-fold in children and 5.1-fold in adults, respectively). (4) Cases of homozygous GG had the highest plasma levels of MCP-1, which increased the likelihood of developing TB. Furthermore, higher levels were observed in children than in adults., Conclusion: These findings suggest that persons bearing the MCP-1 genotype GG produce high concentrations of MCP-1, which increases the risk of active TB infection in Chongqing Han people. These findings are more significant in child patients than in adult patients with TB.