Effect of Mycobacterium vaccae (SRL172) immunotherapy on radiographic healing in tuberculosis

Controlled trials have failed to show an effect of Mycobacterium vaccae immunotherapy on treatment outcome and mortality in patients with tuberculosis (TB); however, several studies have suggested improvement in radiographic clearing and resolution of cavitary disease.

To assess the effect of M. vaccae immunotherapy on radiographic healing in pulmonary TB, chest X-rays from three randomized placebo-controlled trials of M. vaccae given as a single injection during the first 2 weeks of treatment were interpreted by a single, masked assessor using a standard scheme. Endpoints were the overall degree of radiographic improvement or deterioration and changes in cavitary disease at the end of antituberculosis treatment and follow-up.

Of 1018 patients (478 HIV-infected; 540 HIV-uninfected) with an end of treatment or end of follow-up X-ray analyzed, 496 received M. vaccae and 522 received placebo. There was no difference in radiographic improvement or deterioration or cavitary disease at the end of treatment or follow-up comparing the M. vaccae and placebo groups. Results were similar comparing HIV-infected and HIV-uninfected patients.

Adjunctive immunotherapy of drug-susceptible pulmonary TB with M. vaccae during the first 2 weeks of treatment did not improve radiographic responses to treatment or resolution of cavitary disease.