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Objective To investigate the distribution of polymorphisms of SLC11A1 gene,VDR gene,MBL gene and IFNG gene with susceptibility to tuberculosis (TB) in Chinese Han population suffering from drug-sensitive TB and drug-resistant TB so as to identify the correlation between gene polymorphisms and the development of drug-resistant TB.Methods Single nucleotide polymorphisms (SNP) of VDR gene,SLC11A1 gene,MBL gene,IFNG gene were typed and analyzed by pyrosequencing,Real-time Probe and SNaPshot among 229 patients with drug-sensitive TB and 230 patients with drug-resistant TB.Results The polymorphic foci of VDR gene from the drug-sensitive TB group and the drug-resistant TB group showed no significant difference (P＞0.05).The genotype of INT4 site and allelic frequency of SLC11A1 gene for drug-sensitive TB group were significantly different from those for drug-resistant TB group(P=0.031,0.046).If recessive inheritance was assumed,the genotypes of INT4 site from the two groups were significantly different (0R=5.756,95% CI:1.261-26.269,P=0.011).Considering the relationship between OR values under various combination,our findings confirmed that the genetic mode of INT4 site was in accordance with recessive inheritance.The genotypes of Q/P site and allelic frequencies of MBL gene from drug-sensitive and drug-resistant groups were significantly different (P=0.029,0.033).The difference still existed under the hypothesis of recessive inheritance (OR=9.290,95% CI:1.167-73.949,P=0.011).The polymorphic foci of IFNG gene from the two groups showed no significant difference.Conclusion INT4 sites on SLC11A1 gene and Q/P site on MBL gene were probably associated with the development of drug-resistant TB in Chinese Han population.Further study on this issue would be helpful in locating the population at high risk of drug-resistant TB and exploring the effective intervention to decrease the incidence of this disease.
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<p><b>OBJECTIVE</b>To evaluate the effects of microscopic observation drug susceptibility (MODS) in detecting susceptibility of Mycobacterium tuberculosis (MTB) onto four first line anti-tuberculosis drugs.</p><p><b>METHOD</b>The 24-hole cell culture plates were used to test drug susceptibility of MTB on liquid medium, and the best detecting condition of MODS assay was probed; 66 clinical isolates susceptibility to streptomycin (S), isoniazid (H), rifampin (R) and ethambutal (E) were evaluated by using MODS assay and Lowenstein-Jensen (L-J), thereafter, all the inconcordance of isolates between MODS and L-J were tested for the minimal inhibitory concentrations (MIC).</p><p><b>RESULTS</b>Concordance rate of the susceptibility to S, H, R and E in 66 clinical isolates detected by MODS and L-J was 97.0%, 90.9%, 95.5% and 86.4% respectively. If the results obtained by L-J were taken as a golden standard, the sensitivity, specificity, positive and negative predictive value (PPV and NPV) as well as accuracy of susceptibility test to S detected by MODS was 96.0%, 97.6%, 96.0%, 97.6% and 97.0%; 100%, 85.4%, 81.0%, 100% and 90.9% to H; 96.2%, 95%, 92.6%, 97.4% and 95.5% to R; 73.7%, 91.5%, 77.8%, 89.6% and 86.4% to E. There were 20 inconsistent results of 16 isolates by comparing MODS with L-J, and MIC yielded 16 results of those 14 isolates showing identical results with those of the MODS, while 4 results of other 4 isolates identical with L-J.</p><p><b>CONCLUSION</b>MODS method simultaneously provides drug susceptibility to S, H, R and E. MODS might be one of the rapid tools to diagnosing multidrug-resistant tuberculosis as it is rapid, simple, inexpensive and has high concordance with L-J drug susceptibility test.</p>
Subject(s)
Bacteriological Techniques , Methods , Drug Resistance, Multiple, Bacterial , Microbial Sensitivity Tests , Methods , Mycobacterium tuberculosis , Predictive Value of Tests , Sensitivity and Specificity , Tuberculosis, Multidrug-Resistant , MicrobiologyABSTRACT
<p><b>OBJECTIVE</b>To detect the mutations of rpoB gene in Mycobacterium tuberculosis by pyrosequencing and to evaluate the values on detection of rifampin resistance in clinical isolates.</p><p><b>METHODS</b>Using the new technology of pyrosequencing, the mutations in the rifampin resistance determining region (RRDR) of rpoB gene were analyzed. The results were compared with those obtained from methods of the absolute concentration and the minimum inhibitory concentration (MIC).</p><p><b>RESULTS</b>Among the 150 Mycobacterium tuberculosis clinical isolates, 84 were susceptible and 66 resistant to RIF. 54 of the 66 resistant isolates were multidrug-resistant (MDR) strains. Ser531Leu and His526Asp or Tyr, including twelve different genotypes and six codons, were the most common mutations. In the drug susceptibility testing, the accordance rates of the pyrosequencing and the absolute concentration method as well as MIC were 92.7% and 97.8% respectively.</p><p><b>CONCLUSION</b>Not only is the pyrosequencing technology a fast, sensitive and high throughput method in detecting rifampin resistance in Mycobacterium tuberculosis, but also a useful tool in the research of rifampin resistance mechanism.</p>