Primary drug resistance of M. tuberculosis according to the Center of Excellence of the WHO Network of Supranational Reference Laboratories of the CTRI in 2016–2021

Abstract

Introduction. Culture research and testing of Mycobacterium tuberculosis (MBT) for drug susceptibility in the Russian Federation is carried out with uneven quality, which distorts the idea of primary drug resistance (DR). Aim. To study the primary DR of MBT to the main combinations of anti-TB drugs for 2016–2021 according at the Center of Excellence of the WHO Supranational Reference Laboratories Network at the Central Tuberculosis Research Institute. Methods. Data on drug susceptability and frequency of resistance to the main combinations of anti-TB drugs (in accordance with updated definitions) of MBT isolated before treatment were studied in 966 new TB cases from 69 regions of the Russian Federation examined at the Center of Excellence of the WHO Supranational Reference Laboratories Network at the Central Tuberculosis Research Institute from 2016 to 2021. Results. The rate of any primary drug resistance to rifampicin was 46.2%; 95% CI [43.0–49.3], MDR — 45.8%; 95% CI [42.6–48.9], pre-XDR — 24.2%; 95% CI [21.5–27.0], XDR — 5.4%; 95% CI [3.3–8.0]. Over time, there was a decrease in primary MDR MBT from 48.7% in 2016 and 54.9% in 2017 to 36.8% in 2021. The frequency of pre-XDR did not change during the observation period. There was a statistically significant increase in the incidence of primary XDR from 2.1%; 95% CI [0.4–11.1] in 2016 and 0.0% in 2017 to 11.0%; 95% CI [6.1–19.1] in 2021 (p=0.03). Conclusion. The rate of primary MBT drug resistance to the main anti-TB combinations, according to our study, significantly exceeds the overall figures for Russian Federation. This suggests that the situation with MDR, pre-XDR, and XDR tuberculosis in the Russian Federation is much more alarming than we see from the regular reports, while the quality of local microbiological diagnostics on is insufficient.