Evaluation of different primer sets for the rapid diagnosis of tuberculosis.

Pleural fluid samples from patients with exudative effusion who were diagnosed with tuberculous pleuritis are examined using a new designed primer set based on IS1081 gene (IS1081-PCR) and rpoB-PCR. The PCR results are compared with the results of the sample cultures, using Loewenstein-Jensen (LJ) medium and Ziehl-Neelsen (ZN) staining. Of 78 cases that were confirmed as tuberculous pleuritis by histopathology, supported by sputum culture, biochemical markers (adenosine deaminase, gamma interferon and tumor necrosis factor), radiographic and clinical data, 61 (78.2%) were positive by IS1081-PCR, 43 (55.1%) by rpoB-PCR, 17 (21.7%) by culture and 3 (3.8%) by ZN stain. When IS1081-PCR test results were compared with the confirmed culture, the sensitivity, specificity, positive predictive value and negative predictive value for the IS1081-PCR were 94.1, 55.7, 37.2 and 97.1%, respectively. The corresponding values for the rpoB-PCR were 94.1, 26.2, 26.2 and 94.1%, respectively. When tests results were compare with the confirmed radiographic, histopathology, biochemical markers and clinical diagnosis of tuberculous pleuritis, the IS1081-PCR assay is more sensitive, specific and reliable than both rpoB-PCR assay and culture.

Th-1 cytokines gene polymorphism in human brucellosis.

Brucellosis is a worldwide zoonosis. Infection with Brucella species results in the activation of cell-mediated immune response. The interaction between Th1and Th2 cytokines determines the outcome of disease. Production of each cytokine is in turn affected by genetic factors. In this study, we investigated the possible association between Th1 cytokines gene polymorphism and brucellosis. Different genotypes of TNF-alpha, IFN-gamma and IL-2 were determined by polymerase chain reaction-sequence-specific primer in 47 patients with brucellosis and in 166 healthy controls. Allele frequencies of these genotypes were compared using the chi2 test. The results showed a significant difference in the TNF-alpha genotype GG/GG in patients in comparison with controls (76.7% vs. 21%) (P = 0.001, OR = 12.42, 95%CI 5.7-27.7). There was no significant difference in the frequency distribution of the IFN-gamma genotypes between two groups. IL-2 GG genotype at position -330 was about two times more common in cases than in controls, but the difference was not significant (10.6 vs. 4.6 P value = 0.09). This study shows that genetically low producers of TNF-alpha are possibly susceptible to brucellosis and raise doubt about the role of gene polymorphism of INF-gamma in brucellosis which was demonstrated in previous studies. It seems that patients with brucellosis did not have a defect in producing IL-2 with even a trend towards producing higher amounts of this cytokine.