[Relationship between TNF-alpha gene polymorphisms and susceptibility to pulmonary tuberculosis]

Tuberculosis [TB] caused by Mycobacterium tuberculosis, is an infectious disease in human which kills nearly three millions of people annually. Approximately, one - third of the world populations are infected with this bacteria and 5 - 10% of them develop the active form of the disease. Individuals are different in susceptibility to TB infection. These differences might be due to the host characteristics especially genetic factors. TNF- alpha as a pro-inflammatory cytokine, plays a key role in host defense against tuberculosis. Presence of mutation in this gene can influence the effectiveness, performance and capability of immune responses against TB infection. The Aim of this study was to investigate the frequency of TNF- alpha gene polymorphisms and its relation with susceptibility to the pulmonary TB. Sixty healthy controls and 60 TB patients were enrolled. Genotype of TNF[-238], TNF -244, TNF[-308], TNF[-857] and TNF[-863] were determined using PCR-RFLP method. The results were analyzed by Fisher Exact and kappa[2] tests using SPSS v.14 and evaluated with Hardy-Weinberg equilibrium. The results of this study showed a significant difference in TNF-308 and TNF [-857] regions between the control and study groups [P < 0.05]. Presence of mutation in TNF[-308] and TNF [-857] regions may increase the host susceptibility to mycobacterium tuberculosis and genotyping of these regions can be used for screening of the high risk individuals

[ rapid identification of atypical mycobacterium in pulmonary tuberculosis [PTB] patients: evaluation of QUB3232 locus using the VNTR method]

Identification of atypical mycobacterium [Non tuberculosis Mycobacterium; NTM] is important because of the worldwide propagation of these organisms. Recently, molecular studies have identified the specific loci for mycobacterium species by DNA - finger printing methods, but these methods are time-consuming and expensive. In this study, in addition to hsp65 PCR-RFLP method, QUB3232 locus was evaluated for differentiation of atypical mycobacterium from mycobacterium tuberculosis complex. This study was performed on 371 pulmonary and non pulmonary specimens separated from patients with the symptoms of pulmonary tuberculosis [PTB]. After the isolation and culturing of mycobacterium strains using the Lowenstein Jensen media, biochemical tests including production of Niacin, Catalase activity, Nitrate reduction, pigment production and growth rate were performed. Drug susceptibility testing was performed by proportional method. DNA extraction was performed by phenol-chloroform method. hsp65 gene was amplified by PCR. Subsequently the amplicons were digested with three restriction enzymes namely AvaII, HphI and HpaII and electrophoresed on 3% agarose gel. QUB3232 locus was also evaluated for differentiation of atypical mycobacterium and mycobacterium tuberculosis complex. Out of 371 isolates, 32 [8.6%] were multi-drug resistant TB [MDR-TB], 184 [49.5%] were susceptible and 155 [42.5%] were non MDR [combined resistance] that 15% of MDR cases and 25% of non MDR cases were non tuberculosis mycobacterium. Out of 31 slow growing isolates, 58% were M. simiae and 19% were M. kansasii. The sensitivity of QUB3232 locus for differentiation of the atypical mycobacterium from mycobacterium tuberculosis complex was 80%. From the total of 43 NTM samples, 12 [27.9%] were rapid growing and 72% were slow growing. QUB3232 locus has the high discriminative power for differentiation of atypical mycobacterium from the mycobacterium tuberculosis complex, therefore, it can be used as a substitute for PCR-RFLP method