Treatment Outcomes of Isoniazid-Resistant (Rifampicin Susceptible) Tuberculosis Patients in Uzbekistan, 2017-2018.

Tuberculosis patients "resistant to isoniazid and susceptible to rifampicin (Hr-TB)" remain neglected, despite a high burden and poor outcomes. The World Health Organization (WHO) recommends a 6 month regimen consisting of levofloxacin, rifampicin, ethambutol, and pyrazinamide (LRZE) to treat Hr-TB. In contrast, Uzbekistan uses a 9 month regimen (LRZE plus a second-line injectable in the first 3 months). We aimed to assess the treatment outcomes of this novel regimen among Hr-TB patients treated in two regions of Uzbekistan (Fergana and Bukhara) in 2017-2018. We conducted a cohort study involving secondary analysis of routine surveillance data. Of 132 Hr-TB patients, 105 (80%) were successfully treated. Death was the predominant unsuccessful outcome (13, 10%) followed by "treatment failure" (10, 8%) and "lost to follow-up" (4, 2%). High treatment success is an indicator of the potential effectiveness of the novel regimen and adds to the limited global evidence on this issue. However, the sample size was small and there was no comparison group. Since the study was conducted in two regions of Uzbekistan only, the findings have limited generalizability. We recommend future research using an adequate sample size and an appropriate study design (randomized controlled trial or prospective cohort with a control group receiving the WHO-recommended regimen).

Rapid Tuberculosis Diagnostics Including Molecular First- and Second-Line Resistance Testing Based on a Novel Microfluidic DNA Extraction Cartridge.

Xpert MTB/RIF testing has improved tuberculosis (TB) diagnostics and rifampicin (Rif) resistance testing worldwide. However, it has weaknesses, such as its restriction to Rif resistance testing and the inability to use extracted DNA for further testing. Herein, a holistic diagnostic workflow, including TB detection and resistance testing toward Rif, isoniazid, and important second-line drugs (SLDs), based on a novel microfluidic DNA extraction cartridge (TB-Disk), is presented. DNA from 73 precharacterized sputum samples was extracted with TB-Disk, including 45 clinical and bacteriologically confirmed TB samples, nine TB-negative samples, and 19 sputum samples spiked with twofold dilutions of TB bacteria. The extracted DNA was subjected to further testing with FluoroType MTB (FT-MTB), GenoType MTBDRplus (GT-plus), and GenoType MTBDRsl. A total of 100% (20/20) and 72% (18/25) of smear-positive and smear-negative TB samples were identified as Mycobacterium tuberculosis complex positive. A total of 79% (33/42) of subsequently GT-plus tested samples yielded a valid result. Eight samples were identified as multidrug-resistant TB by GT-plus and further tested for resistance toward SLDs using GenoType MTBDRsl, yielding 75% (6/8) valid results. FT-MTB with cartridge-based DNA extraction (Disk-DNA) and DNA extracted with FluoroLyse yielded similar analytical sensitivities. FT-MTB with Disk-DNA was 100% specific. TB-Disk in combination with FT-MTB enables sensitive TB detection. The Disk-DNA can be further used for screening resistance toward first-line drugs and SLDs.