Exploring the Link Between Tuberculosis Treatment and Re-Infection Risk

Impact of Anti-Tuberculosis Drugs on Microbiota and Re-Infection Risk

Understanding Tuberculosis

A recent study has examined how anti-tuberculosis medications might influence the microbiota and potentially heighten the risk of re-infection. Tuberculosis, caused by the microbe Mycobacterium tuberculosis, is one of humanity’s oldest diseases. This bacterium has evolved over time, enabling it to persist within the human body. The World Health Organization estimates that approximately one-third of the global population carries M. tuberculosis, which primarily targets the lungs and can lead to multiple infections. Upon entering the body, M. tuberculosis establishes a primary infection, often with few or no symptoms, which can resolve on its own. However, the bacterium can remain dormant for years and may reactivate under favorable conditions, leading to active tuberculosis.

Challenges in Diagnosis and Treatment

Diagnosing tuberculosis can be quite challenging due to the similarity of its symptoms to other respiratory and non-respiratory illnesses. Laboratory methods face difficulties, including the slow growth rate of the bacterium and varying sensitivities to skin tests among individuals. Treatment typically involves a regimen of multiple drugs over several months, complicating adherence and increasing the risk of toxic liver effects. While antibiotics effectively eliminate pathogens, they can also disrupt the beneficial human microbiota.

Effects of Tuberculosis Treatment on Gut Microbiota

Research has indicated that antibiotic use can elevate the risk of infectious diseases by affecting the microbiota. A recent study aimed to investigate the interactions between anti-tuberculosis drugs and the intestinal microbiota, as well as their implications for re-infection risk by M. tuberculosis. The findings were published in Mucosal Immunology.

The researchers studied the effects of commonly prescribed anti-tuberculosis drugs, isoniazid (INH), pyrazinamide (PYZ), and rifampicin (RIF), on the microbiota of mice. INH and PYZ specifically target the bacterium’s cell wall, while RIF is a broader-spectrum antibiotic. Mice were treated with either a combination of INH and PYZ or RIF for eight weeks, after which the gut microbiota composition was analyzed. Results indicated that both treatment regimens altered the microbiota, but the combination of INH and PYZ increased susceptibility to infection compared to RIF treatment alone.

Link Between Gut Microbiota and Lung Immune Defenses

The researchers further explored the relationship between the intestinal microbiota and immune responses in the lungs, which are primarily affected by tuberculosis. They demonstrated that the INH/PYZ treatment altered the metabolism of alveolar macrophages—immune cells that serve as the first line of defense against M. tuberculosis in the lungs. These metabolic changes compromised the macrophages’ ability to control the infection.

Future Research Directions

In conclusion, the study highlights how anti-tuberculosis drugs impact the intestinal microbiota in mice, noting that the combination of INH and PYZ not only disrupts this microbial community but also raises the risk of M. tuberculosis re-infection. The alterations in the microbiota trigger metabolic changes in lung immune cells, impairing their function against the bacterium. Further research is essential to elucidate the specific mechanisms connecting gut microbiota to lung immunity. This study sets the foundation for future investigations into the effects of tuberculosis treatment on the microbiota of human patients.

References

Khan, N., Mendonca, L., Dhariwal, A., Fontes, G., Menzies, D., Xia, J., Divangahi, M., & King, I. L. (2019). Intestinal dysbiosis compromises alveolar macrophage immunity to Mycobacterium tuberculosis. Mucosal Immunology.
Anti-TB drugs can increase risk of TB re-infection. https://www.eurekalert.org/pub_releases/2019-03/mu-ad032219.php
Lyon, S. M., & Rossman, M. D. (2017). Pulmonary Tuberculosis. Microbiology Spectrum, 5(1), 1–13.
Leung, C. C., Lange, C., & Zhang, Y. (2013). Tuberculosis: Current state of knowledge: An epilogue. Respirology. 18(7), 1047-1055.
Dobbs, T. E., & Webb, R. M. (2017). Chemotherapy of Tuberculosis. Microbiology Spectrum, 5(2), 1–16.