A woman came to the clinic with her 41-year old husband. Her husband was diagnosed with pulmonary tuberculosis (TB) last month and had come back for a follow-up consult. The husband reported that he had been routinely taking the prescribed anti-TB drugs since then. During the consultation, she mentioned that she read some information online regarding the benefits of vitamin D supplements for TB patients. She was wondering whether or not vitamin D supplements could improve her husband's treatment outcome if he were to take them along with his anti-TB drugs.
Tuberculosis infection (TB) is one of the top ten causes of death worldwide and is due to Mycobacterium tuberculosis (Mtb) infection. Although this bacterium can affect numerous organs, the respiratory system remains the most prominently affected. TB is a contagious disease, and air serves as the main mode of transmission.
Due to its ease of transmission, early prevention and treatment are crucial. Early diagnosis can be done since a susceptible patient is suspected of having a TB infection. The examination includes taking a history, physical examination, radiological chest examination, and the laboratory culture of Mycobacterium tuberculosis by culture of sputum or tissue biopsy. A sputum smear test can also be conducted to assess the degree of infection. Treatment for tuberculosis includes a combination of drugs administered for at least 6 months, and the conversion of sputum smear test (SSC) from positive to negative indicates successful treatment and generally occurs after two months of treatment. The two-month sputum conversion rate is currently considered as the preferred endpoint because this marker has a significant correlation with combined response rates, relapse, and intermediate bacteriological endpoint. Standard treatment for TB consists of 4 antituberculosis drugs, which are isoniazid, rifampin, pyrazinamide, and either ethambutol or streptomycin. This regimen is given for 2 months with 60 doses, followed by 4 months of treatment with only isoniazid and rifampin with 120 doses. The choice of treatment depends on the patients' drug susceptibility and the response following treatment.
Vitamin D has a vital role in the body's natural defense mechanism towards infection since it promotes the role of macrophages and monocytes which is important in pathogenesis. In infection caused by Mycobacterium tuberculosis (Mtb), calcidiol, the major circulating metabolite of vitamin D, supports the induction of innate antimicrobial immune response by causing Mtb growth restriction. Calcidiol is metabolized by CYP27B1 into its active form, calcitriol. Calcitriol exerts its antimicrobial activity by modulating the reactive oxygen intermediates, the induction of antimicrobial peptides, and autophagy. Calcitriol plays a key role in the maintenance of immune homeostasis and in tuberculosis and works indirectly by suppressing MHC class II and directly suppresses IFN-gamma and IL-2 from CD4 Th1 cells. Coussens et al. have also shown that high dose of vitamin D supplementation suppresses antigen-stimulated proinflammatory cytokine responses and accelerates the resolution of IL-4, CC chemokine ligand 5, and IFN-alpha secretion during the administration of antituberculosis drugs.
Thus, some studies have suggested adjunct vitamin D supplementation to enhance the response to antituberculosis therapy. However, several studies have differing results regarding the impact of vitamin D as adjunctive therapy to TB patients. Therefore, the purpose of this article is to update and clarify the impact of adjunct vitamin D supplementation in achieving an early smear sputum conversion rate among pulmonary TB patients.