Nyaditum Resae® as a Co-adjuvant During Treatment for Active Pulmonary Tuberculosis and Its Impact on the Gut Microbiota

About one tenth of the 1.7 billion individuals infected with Mycobacterium tuberculosis (Mtb) will progress to active tuberculosis (TB). This probability increases in people with human immunodeficiency virus (HIV) and other risk co-morbidities such as malnutrition, diabetes and substance abuse. Chronic microbial colonisation with unrelated bacteria are associated with TB pathogenesis (e.g., mice colonised with Helicobacter hepaticus exhibit poor control of TB), indicating that the gut microbiota may modulate progression to active TB. Furthermore, first-line TB treatment (Isoniazid, Rifampicin, Ethambutol, Pyrazinamide; HREZ) depletes gut commensal bacteria (Ruminococcus, Coprococcus and Bifidobacterium) with immunomodulatory roles \[interleukin (IL)-1, interferon (IFN)-γ and Th17 responses, respectively). Recent work identified heat-killed Mycobacterium manresensis (hkMm), a harmless member of the fortuitum complex naturally found in drinking water, as a promising candidate for reducing the risk of active TB. Mtb-infected mice treated with hkMm had significantly reduced lung pathology (fewer and smaller lesions,) bacillary load and proinflammatory cytokines (TNF-α, IFN-γ, IL-6, and IL-17) compared to untreated control mice, and in mice receiving hkMm with HREZ, survival rates were significantly increased. Moreover, mice treated with hkMm had increased microbial diversity and an altered gut microbial composition relative to untreated mice. This could prove beneficial for TB patients during prolonged antibiotic treatment as supplementation with hkMm may help protect gut microbiota, and potentially improve clinical outcome. In individuals with and without latent M. tuberculosis infection, two weeks of daily oral doses of Nyaditum resae® (a preparation of hkMm approved as a food supplement by Manremyc) demonstrated enhanced effector and memory specific regulatory T-cell responses. Similar clinical trials with Nyaditum resae® are currently being done in paediatrics (NCT02581579) and close contacts of active TB cases in Tbilisi, Georgia (NCT02897180; 2017-2023). The probiotic is also being registered as a food supplement in several countries. In the proposed study, the efficacy of Nyaditum resae® in reducing antibiotic-associated gut dysbiosis and disease progression in patients with active TB will be tested. To do this, the investigators will assess changes in the microbiota during treatment (with or without Nyaditum resae® supplementation) and attempt to identify genera associated with a favourable or unfavourable treatment outcome in TB patients.