Highest prevalence of the Mycobacterium tuberculosis Beijing genotype isolates in patients newly diagnosed with tuberculosis in the Novosibirsk oblast, Russian Federation

In order to assess the genetic diversity of Mycobacterium tuberculosis in the Novosibirsk Region and determine profiles of resistance, 106 M. tuberculosis isolates were analysed. Fifty (47%) isolates were identified using variable number tandem repeat typing as being in the Beijing family, of which eight (16%) were type M2 isolates with the genetic profile 233325153533424 and eight (16%) were type M11 isolates with the genetic profile 233325173533424, both of which are widespread in Russia. Mutations associated with resistance to isoniazid and rifampicin were identified. Of 48 isolates with resistance to isoniazid, 42 (87.5%) contained a Ser(315)-> Thr substitution in the katG gene and one contained a T -> A substitution at position -34 of the promoter region of the ahpC gene. Of 31 isolates with resistance to rifampicin, 19 (61 %) each contained a mutation (TCG -> JTG) at codon 531 of the rpoB gene. Two isolates each contained a mutation (GAC -> GTC) at codon 516 of the rpoB gene and two others each contained a substitution at codon 526 of the rpoB gene, leading to a His -> Asn substitution in one case and a His -> Asp substitution in another case. One isolate contained a mutation (CTG -> CCG) at codon 533 of the rpoB gene. An association between the Beijing genotype and multidrug resistance was demonstrated (R=0.2, P=0.032). However, it was interesting to note that a significant proportion (46%) of isolates were sensitive to all drugs tested.