Age- and gender-specific effects on VDR gene polymorphisms and risk of the development of multiple sclerosis in Tunisians: a preliminary study.

The vitamin D receptor (VDR) polymorphisms have been reported to be associated with multiple sclerosis (MS); however, evidence remains conflicting. In this report, we investigated the association between two single nucleotide polymorphisms (SNPs) TaqI and ApaI of VDR gene and risk development of MS. TaqI and ApaI SNPs were detected by PCR-RFLP from the DNA of 60 Tunisian patients with MS and 114 healthy controls. Our results show a significant difference of the allelic frequency distribution between the case and control groups for TaqI SNP (P = 0.01), but genotype frequencies were not significantly different (P = 0.07 and 0.23). When adjusting frequency distribution of different alleles and genotypes by age, we found that the difference between the T allele frequencies of this SNP in the group of patients age [15-24] in comparison with the control group of the same age group was statistically significant (P = 0.026). Moreover, frequency of the T allele was significantly higher in male patients compared with controls of the same sex (P = 0.017). However, neither the genotype nor the allele frequency distribution was significantly different between the MS and control populations for the ApaI SNP. Our preliminary results indicate that VDR gene polymorphism could be associated with susceptibility to MS. The role of VDR gene polymorphism should be further studied in other large populations, and the distribution of other polymorphism, such as FokI and BsmI, should be also analysed to confirm another susceptibility polymorphisms gene for MS and to obtain more adequate strategies for treatment of MS.

Molecular characterisation of isoniazid- and rifampicin-resistant Mycobacterium tuberculosis in Central Tunisia.

The aim of our study was to genotypically characterise isoniazid (INH) and rifampicin (RMP) resistant Mycobacterium tuberculosis isolates in Sousse, Central Tunisia, using DNA sequencing and multispacer sequence typing (MST). The results show that 27/28 (96.4%) and 1/28 (3.6%) INH-resistant isolates yielded respectively the kat G S315T and the inh A - 15C → T mutations. Two-thirds of RMP-resistant isolates yielded the rpo B D516V mutation and one sixth yielded either H526D or S531L mutations. Genotyping analysis revealed the multiclonal spread of drug-resistant isolates in Central Tunisia. Data presented here complete the previously published map of resistant M. tuberculosis isolates and highlight their regional disparity in Tunisia.

Evaluation of a simplified IS6110 PCR for the rapid diagnosis of Mycobacterium tuberculosis in an area with high tuberculosis incidence.

PURPOSE: To assess the diagnostic yield of a simplified IS6110-PCR in an area with high tuberculosis incidence. METHODS: Pulmonary (218) and extrapulmonary (121) samples were collected from 236 patients including smearpositive leprosy patients. All samples were processed to detect acidfast bacilli by microscopy, culture on solid media and PCR. To remove PCR inhibitors, three washing steps of the decontaminated pellet were included before mycobacterial cell lysis by heat treatment. No detergents, enzymes, or chelating agents were used. From the 339 samples, 34 were selected basing on their large volume and were tested by the commercial kit GenoType Mycobacteria Direct (GTMD) (VER 4, Hain Lifescience, Germany) in addition to the tests cited above. RESULTS: The overall sensitivity and specificity of PCR were 93.8 and 98.6% for pulmonary samples, 63.6 and 100% for extrapulmonary samples, respectively. The assay detected MTC in 94.2% of smear positive samples with a positive predictive value of 100%. No inhibition was found among seven samples that were PCR negative but bacteriological confirmed as containing Mycobacterium tuberculosis. No false positive result occurred with samples from leprosy patients. The sensitivities for PCR and GTMD were 81.8 and 75%, respectively. CONCLUSION: PCR could efficiently complement conventional bacteriological tools for the rapid diagnosis of tuberculosis but cannot replace them.

Rapid detection of immunoglobulin G against Mycobacterium tuberculosis antigens by two commercial ELISA kits.

SETTING: Tunisia. OBJECTIVE: To assess the clinical usefulness of the commercial Pathozyme-Myco G (Myco G) and Pathozyme TB complex plus (Patho) enzyme-linked immunosorbent assay (ELISA) kits for the rapid diagnosis of active tuberculosis (TB) and to distinguish between active TB and non-TB pulmonary diseases in Tunisian patients. DESIGN: Immunoglobulin G mediated humoral immune response against mycobacterial antigens (38 kDa and lipoarabinomannan, Myco G; 16 and 38 kDa, Patho) was evaluated in a group of active TB patients (128 smear-positive pulmonary and 33 extra-pulmonary samples) and in a control group (107 patients with non-tuberculous lung disease and two with leprosy). Active TB cases were confirmed by Mycobacterium tuberculosis culture from clinical samples. RESULTS: The sensitivity of the Myco G test was 71% in active TB (pulmonary and extra-pulmonary), while the specificity was 100%. The Patho test showed a sensitivity of 43.5% with a specificity of 96.3%. A combination of both tests showed a sensitivity of 81% and a specificity of 96.3%. CONCLUSIONS: Both ELISA tests were simple and easy to perform. Their combined use led to an increase in the diagnostic accuracy of active TB and its discrimination from non-TB pulmonary diseases. They could therefore be used as screening tools in poorly equipped laboratories in TB-endemic regions.