Genotyping of drug-resistant Mycobacterium tuberculosis strains isolated from the patients in Anhui province with variable number tandem repeat method

Objective To genotype resistant Mycobacterium tuberculosis strains isolated from the patients in Anhui province with a new genotyping method based on the variable number tandem repeats(VNTR). MethodsTo select 13 VNTR loci and develop a fast fingerprinting technology for M.tuberculosis strains by polymerase chain reaction(PCR) and agarose gel electrophoresis technique and analyzed the polymorphism of DNA fingerprinting of drug resistant M.tuberculosis . Results Seventy eight M.tuberculosis strains detected with 13 VNTR loci were classified into four types(Ⅰ, Ⅱ, Ⅲ, Ⅳ) based on their characters of PCR amplified fingerprints, type Ⅰ 3.8%(3/78),type Ⅱ 6.4%(5/78), type Ⅲ 10.3%(8/78) and type Ⅳ 79.5%(62/78). In type Ⅳ group, the main drug resistant strains were multidrug resistant ones(45.8%) and rifampin resistant strains(22.6%). ConclusionThe results showed that the prevalence of drug resistant tuberculosis was primarily due to the transmission of type Ⅳ in Anhui province. It is suggested that surveillance of genotype Ⅳ needs to be strengthened.