Associations between Mycobacterium tuberculosis Beijing genotype and drug resistance to four first-line drugs: a survey in China / 医学前沿

Investigations on the genetic diversity of Mycobacterium tuberculosis in China have shown that Beijing genotype strains play a dominant role. To study the association between the M. tuberculosis Beijing genotype and the drug-resistance phenotype, 1286 M. tuberculosis clinical isolates together with epidemiological and clinical information of patients were collected from the center for tuberculosis (TB) prevention and control or TB hospitals in Beijing municipality and nine provinces or autonomous regions in China. Drug resistance testing was conducted on all the isolates to the four first-line anti-TB drugs (isoniazid, rifampicin, streptomycin, and ethambutol). A total of 585 strains were found to be resistant to at least one of the four anti-TB drugs. The Beijing family strains consisted of 499 (53.20%) drug-sensitive strains and 439 (46.80%) drug-resistant strains, whereas the non-Beijing family strains comprised 202 (58.05%) drug-sensitive strains and 146 (41.95%) drug-resistant strains. No significant difference was observed in prevalence (χ= 2.41, P > 0.05) between the drug-resistant and drugsensitive strains among the Beijing family strains. Analysis of monoresistance, multidrug-resistant TB, and geographic distribution of drug resistance did not find any relationships between the M. tuberculosis Beijing genotype and drug-resistance phenotype in China. Results confirmed that the Beijing genotype, the predominant M. tuberculosis genotype in China, was not associated with drug resistance.

Establishment and application of a standard IS6110-RFLP method in the study of molecular genotyping analysis on Mycobacterium tuberculosis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To develop a standardized IS6110-restriction fragment length polymorphism (RFLP) method, used for evaluating the capacity of genotyping.</p><p><b>METHODS</b>IS6110-RFLP of 78 Mycobacterium (M.) tuberculosis strains were studied by bio-molecular techniques including DNA isolation, PCR, restriction endonuclease enzyme analysis, southern blotting, agarose gel electrophoresis, together with data analysis by software Gel-Pro analyzer 3.1 and BioNumerics (Version 5.0).</p><p><b>RESULTS</b>IS6110-RFLP method was established and standardized successfully, including DNA isolation, PCR, restriction endonuclease enzyme analysis, southern blotting, agarose gel electrophoresis and usage of the analysis software with standard parameters. By this method, 78 M. tuberculosis isolates were classified into 75 genotypes which belonged to 11 different clusters. Of all the isolates, 66.7% (52/78) belonged to a main cluster.</p><p><b>CONCLUSION</b>Standard IS6110-RFLP method was established successfully. This method had powerful capacity for genotyping and strain level identification and could be used for the surveillance on pathogens of M. tuberculosis in China.</p>