The WHO has declared tuberculosis (TB) a global health emergency. Therefore, there is an urgent need to discover and develop new anti–TB drugs. Here we report on a new category of 5–substituted pyrimidine nucleosides as potent inhibitors of Myco–bacterium tuberculosis growth in vitro. A series of 2ʹ–deoxy–, 3ʹ–azido–2ʹ,3ʹ–dideoxy–, and 3ʹ–amino–2ʹ,3ʹ–dideoxypyrimidine nucleoside analogues bearing lengthy flexible alkyloxymethyl substituents exhibited marked inhibitory activity against M. tuberculosis in vitro. 5–Dodecyloxymethyl–2ʹ–deoxyuridine was found to be a potent inhibitor of M. tuberculosis propagation in vitro. In contrast, monophosphates of the tested nucleosides were devoid of antimycobacterial activity. This new class of inhibitors seems to be a promising chemotherapeutic agent against TB and merits further studies.

To study the transmissibility of drug resistant mutant clones, M. tuberculosis samples were isolated from the patients of the clinical department and the polyclinic of the Central TB Research Institute (n = 1455) for 2011-2014. A number of clones were phenotypically resistant to rifampicin (n = 829), isoniazid (n = 968), and fluoroquinolones (n = 220). We have detected 21 resistance-associated variants in eight codons of rpoB, six variants in three codons of katG, three variants in two positions of inhA, four variants in four positions of ahpC, and nine variants in five codons of gyrA, which were represented in the analyzed samples with varied frequencies. Most common mutations were rpoB 531 Ser→Leu (77.93%), katG 315 (Ser→Thr) (94.11%), and gyrA 94 (Asp→Gly) (45.45%). We found that the mutations at position 15 of inhA (C→T) (frequency of 25.72%) are commonly associated with katG 315 (Ser→Thr). This association of two DNA variants may arise due to the double selection by coexposure of M. tuberculosis to isoniazid and ethionamide. The high transmissibility of mutated strains was observed, which may be explained by the minimal influence of the resistance determinants on strain viability. The high transmissibility of resistant variants may also explain the large populational prevalence of drug-resistant TB strains.

No abstract

С целью характеристики фенотипической лекарственной чувствительности штаммов МБТ с мутациями, ассоциированными с устойчивостью к изониазиду и рифампицину, представлены результаты внедрения разработанного в отделе микробиологии ЦНИИТ алгоритма ускоренного определения ЛЧ МБТ к расширенному спектру ПТП за период 2011-2015 гг. на примере 859 культур мБт, у которых на первом этапе исследования были выявлены мутации в генах rpoB, katG и inhA. Генотипическое определение ЛУ к рифампицину и изониазиду проводили с использованием набора «Амплитуб-МЛУ-РВ» (Синтол, Россия). Определение лекарственной чувствительности МБТ к расширенному спектру ПТП (8 основных ПТП 1 и 2 ряда- H, R, E, Z, Eto, Am, Cm, Lfx, и 3 препарата резерва - Mfx, PАS, Lzd) проводили в системе BACTEC MGIT 960. Среди штаммов с генотипической МЛУ часто встречались штаммы с пре-ШЛУ (300/859, 34,9%) и ШЛУ (268/859, 31,2%), включая штаммы с тотальной устойчивостью к 8-ми основным ПТП155/859 (18,04%). Для штаммов, устойчивых к левофлоксацину, в более чем 90% случаев показана перекрестная резистентность к моксифлоксацину в концентрации 0,5 мкг/мл и в 65% случаев чувствительность к моксифлоксацину в концентрации к 2 мкг/мл, что демонстрирует целесообразность проведения для левофлоксацин-устойчивых штаммов ТЛЧ к моксифлоксацину с использованием двух критических концентраций. Полученные результаты подтверждают необходимость применения комплекса генотипических и фенотипических методов определения лекарственной чувствительности МБТ для быстрой изоляции наиболее опасных групп бактериовыделителей и получения максимально полной информации о чувствительности возбудителя.

The WHO has declared tuberculosis ( TB ) a global health emergency. Therefore, there is an urgent need to discover and develop new anti– TB drugs. Here we report on a new category of 5–substituted pyrimidine nucleosides as potent inhibitors of Myco–bacterium tuberculosis growth in vitro. A series of 2ʹ–deoxy–, 3ʹ–azido–2ʹ,3ʹ–dideoxy–, and 3ʹ–amino–2ʹ,3ʹ–dideoxypyrimidine nucleoside analogues bearing lengthy flexible alkyloxymethyl substituents exhibited marked inhibitory activity against M. tuberculosis in vitro. 5–Dodecyloxymethyl–2ʹ–deoxyuridine was found to be a potent inhibitor of M. tuberculosis propagation in vitro. In contrast, monophosphates of the tested nucleosides were devoid of antimycobacterial activity. This new class of inhibitors seems to be a promising chemotherapeutic agent against TB and merits further studies.