Transmission of extensively drug-resistant and multidrug resistant Mycobacterium tuberculosis in families identified by genotyping / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Diagnosis and appropriate treatment of multidrug-resistant tuberculosis (MDR-TB) remain major challenges. We sought to elucidate that persons who share a household with drug resistance tuberculosis patients are at high risk for primary drug resistance tuberculosis and how to prevent these outbreaks.</p><p><b>METHODS</b>We used 12-locus mycobacterial interspersed repetitive unit and 7-locus variable-number tandem repeat to identify household transmission of extensively drug resistant and multiple drug resistant Mycobacterium tuberculosis in three families admitted in Shanghai Pulmonary Hospital affiliated with Tongji University. Drug susceptibility tests were done by the modified proportion method in the MGIT 960 system in the same time. Clinical data were also obtained from the subjects' medical records.</p><p><b>RESULTS</b>All of the six strains were defined as Beijing genotype by the deletion-targeted multiplex PCR (DTM-PCR) identification on the genomic deletion RD105. Strains from family-1 had the same minisatellite interspersed repetitive unit (MIRU) pattern (232225172531) and the same MIRU pattern (3677235). Strains from family-2 had the same MIRU pattern (2212261553323) and the same MIRU pattern (3685134). Strains from family-3 did not have the same MIRU pattern and they differed at only one locus (223326173533, 223325173533), and did not have the same VNTR pattern with two locus differed (3667233, 3677234).</p><p><b>CONCLUSIONS</b>Household transmission exists in the three families. A clear chain of tuberculosis transmission within family exists. Tuberculosis susceptibility should be considered when there is more than one tuberculosis patients in a family. Household tuberculosis transmission could be prevented with adequate treatment of source patients.</p>

Evaluation of pyrosequencing for the detection of rpoB gene mutation in Mycobacterium tuberculosis / 中华预防医学杂志

<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>