There is limited understanding of the role of host metabolism in the pathophysiology of human tuberculosis (TB). Using high-resolution metabolomics with an unbiased approach to metabolic pathway analysis, we discovered that the tryptophan pathway is highly regulated throughout the spectrum of TB infection and disease. This regulation is characterized by increased catabolism of tryptophan to kynurenine, which was evident not only in active TB disease but also in latent TB infection (LTBI). Further, we found that tryptophan catabolism is reversed with effective treatment of both active TB disease and LTBI in a manner commensurate with bacterial clearance. Persons with active TB and LTBI also exhibited increased expression of indoleamine 2,3-dioxygenase-1 ( IDO-1 ), suggesting IDO-1 mediates observed increases in tryptophan catabolism. Together, these data indicate IDO-1–mediated tryptophan catabolism is highly preserved in the human response to Mycobacterium tuberculosis and could be a target for biomarker development as well as host-directed therapies.

The WHO has recommended the implementation of rapid diagnostic tests to detect and help combat M/XDR tuberculosis (TB). There are limited data on the performance and impact of these tests in field settings. The performance of the commercially available Genotype MTBDRplus molecular assay was compared to conventional methods including AFB smear, culture and drug susceptibility testing (DST) using both an absolute concentration method on Löwenstein-Jensen media and broth-based method using the MGIT 960 system. Sputum specimens were obtained from TB suspects in the country of Georgia who received care through the National TB Program. Among 500 AFB smear-positive sputum specimens, 458 (91.6%) had both a positive sputum culture for Mycobacterium tuberculosis and a valid MTBDRplus assay result. The MTBDRplus assay detected isoniazid (INH) resistance directly from the sputum specimen in 159 (89.8%) of 177 specimens and MDR-TB in 109 (95.6%) of 114 specimens compared to conventional methods. There was high agreement between the MTBDRplus assay and conventional DST results in detecting MDR-TB (kappa = 0.95, p<0.01). The most prevalent INH resistance mutation was S315T (78%) in the katG codon and the most common rifampicin resistance mutation was S531L (68%) in the rpoB codon. Among 13 specimens from TB suspects with negative sputum cultures, 7 had a positive MTBDRplus assay (3 with MDR-TB). The time to detection of MDR-TB was significantly less using the MTBDRplus assay (4.2 days) compared to the use of standard phenotypic tests (67.3 days with solid media and 21.6 days with broth-based media). Compared to conventional methods, the MTBDRplus assay had high accuracy and significantly reduced time to detection of MDR-TB in an area with high MDR-TB prevalence. The use of rapid molecular diagnostic tests for TB and drug resistance should increase the proportion of patients promptly placed on appropriate therapy.

Mentoring is a critical component of career development for research scientists and is related to mentee success both in terms of career selection and advancement. However, there are limited data on the role of mentoring in low- and middle-income countries (LMICs). Cross-cultural mentorship programs have the potential to foster the transfer of knowledge and the development of capacity to resource-poor settings. This formative evaluation explores the cultural context of mentoring in the countries of Georgia and Ethiopia. Results were used to build culturally relevant mentor training programs for two Global Infectious Disease Research Training Programs focused on tuberculosis funded by the Fogarty International Center at the US National Institutes of Health. Four focus group discussions were conducted with research trainees and mentors to explore the perceptions of mentorship, identify obstacles for successful mentoring, and generate recommendations to strengthen mentoring in each program situated in a LMIC. Data revealed the barriers to mentoring in Ethiopia and Georgia included gaps in knowledge about mentoring roles and responsibilities, lack of knowledge about the responsibilities of the trainee in a mentoring relationship, and the need to set clear expectations between mentors and trainees. All of the focus group participants desired formal mentor training. These data informed six key components of the development and implementation of the mentor training programs in both countries. The topics included the following: a foundation in mentoring, establishing expectations between mentees and mentors, increasing interactions between mentees and mentors, additional mentor training, a case study curriculum, and methods of evaluating mentoring relationships.

SETTING: The country of Georgia has a high burden of multi- (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). OBJECTIVE: To assess the performance of the GenoType® MTBDRsl assay in the detection of resistance to kanamycin (KM), capreomycin (CPM) and ofloxacin (OFX), and of XDR-TB. DESIGN: Consecutive acid-fast bacilli smear-positive sputum specimens identified as MDR-TB using the MTBDRplus test were evaluated with the MTBDRsl assay and conventional second-line drug susceptibility testing (DST). RESULTS: Among 159 specimens, amplification was adequate in 154 (97%), including 9 of 9 culture-negative and 2 of 3 contaminated specimens. Second-line DST revealed that 17 (12%) Mycobacterium tuberculosis isolates were XDR-TB. Compared to DST, the MTBDRsl had 41% sensitivity and 98% specificity in detecting XDR-TB and 81% sensitivity and 99% specificity in detecting OFX resistance. Sensitivity was low in detecting resistance to KM (29%) and CPM (57%), while specificity was respectively 99% and 94%. Median times from sputum collection to second-line DST and MTBDRsl results were 70–104 vs. 10 days. CONCLUSION: Although the MTBDRsl assay had a rapid turnaround time, detection of second-line drug resistance was poor compared to DST. Further genetic mutations associated with resistance to second-line drugs should be included in the assay to improve test performance and clinical utility.

Tuberculosis treatment is challenging, especially among people with drug-resistant forms of tuberculosis. The introduction of fully oral modified short treatment regimen has a great potential to shorten duration of treatment, improve safety and ultimately increase treatment success rate. In 2019 Georgia has piloted the modified fully oral shorter treatment regimen in a routine programmatic condition. Our study aimed to evaluate effectiveness and safety of the modified shorter treatment regimen in Georgia among the first 25 consecutively enrolled patients with rifampicin-resistant tuberculosis with proven sensitivity to fluoroquinolone and without prior exposure to second-line tuberculosis drugs. Regimen consisted of 9-month daily administration of bedaquilline, linezolid, levofloxacin, clofazimine and cycloserine. Study patients were enrolled between March-August 2019. We used a national electronic surveillance system, medical records and active TB drug-safety monitoring and management database to extract study related data. The mean age of the study participants was 48 years, 68% were male, 8% were HIV positive, 16% had diabetes and 12% tested positive for hepatitis C infection. The median time to culture conversion among 16 patients who were culture positive at treatment initiation was 1.0 (95% CI: 1.0-2.0) month. Of those, by the end of treatment 15 patients converted to negative. Out of the 25 patients in the study cohort 22 (88%) had successful treatment outcome, one patient (4%) died and two (8%) were lost to follow up. The regimen was largely well tolerated. Three patients (12%) experienced serious adverse events, of which in two cases were possibly related to TB drugs in the regimen. Seven patients developed adverse events of interest in eight instances, including musculoskeletal (twice), psychiatric, gastrointestinal disorders, hepatotoxicity, peripheral neuropathy, cardiotoxicity and myelosuppression (once each). In four patients (16%) the duration of the treatment was extended beyond nine months due to insufficient radiological improvements. Our findings demonstrate that good treatment outcomes are achievable in people with fluoroquinolone-sensitive tuberculosis within routine programmatic conditions using fully oral modified short treatment regimen. The extensive use of fully oral modified shorter treatment regimen in Georgia and other high priority countries in the World Health Organization European Region is warranted.

Background: High-resolution metabolomics has shown promise for identifying blood-based biomarkers of tuberculosis (TB). We sought to discover a metabolic signature to detect pulmonary TB disease and monitor treatment response. Methods: Plasma from Ethiopian persons with pulmonary TB at diagnosis (n = 82) was compared to household contacts with TB symptoms (n = 104) and 2, 6, and 12 months after treatment initiation. Participants were divided into training and test sets for model building, with additional validation using independent cohorts from the countries of Georgia (n = 89) and South Africa (n = 85). Signatures were further evaluated in nonhuman primates infected with Mycobacterium tuberculosis (Mtb). Results: Among the metabolites that most significantly differed in concentration, tryptophan (Trp) and retinol were significantly decreased in persons with TB disease (45.2 vs 62.5 μM and 4.1 vs 8.2 μM, respectively), while kynurenine (Kyn) was significantly increased (2.1 vs 1.6 μM; q < .0001 for all). A signature that included the Kyn/Trp ratio and retinol showed excellent classification for TB disease (area under the curve [AUC] = 0.97). The signature had an AUC of 0.97 in HIV-positive and 0.95 in HIV-negative persons with TB disease from South Africa and 0.93 in TB patients from Georgia. In Ethiopian participants, signature scores decreased after 2 months (0.85 to 0.42) and 6 months of TB treatment (0.42 to 0.18; P < .0001 for both) to similar levels as controls. Plasma retinol also declined in nonhuman primates infected with Mtb 15–16 weeks after infection (5.9 vs 3.6 μM; P < .001). Conclusions: The plasma Kyn/Trp ratio and retinol represents a promising metabolic signature that could advance TB diagnostics.