Emulsifying Mycobacterium brumae in olive oil appeared promising for producing a robust immune response in preclinical tests. Recent research has indicated that M brumae is a safer alternative to M bovis bacillus Calmette-Guerin (BCG), an effective treatment routinely used for high-risk non-muscle–invasive bladder cancer and carcinoma in situ.1

Currently, approximately 5% of patients treated with BCG develop serious side effects, including BCG infection. In contrast, no cases of infection with M brumae were described in humans or animals.

The challenge with M brumae is that mycobacteria cells, which have a high lipid content in their cell walls, tend to clump when placed in the water-based solutions used for intravesical instillation in patients with bladder cancer. This clumping may interfere with the interaction of the mycobacteria-host cells and negatively influence their antitumor effects.

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Dispersing the M brumae in olive oil led to favorable conditions for reaching the bladder epithelium in vivo. Specifically, the emulsion of M brumae in olive oil was less hydrophobic, had a lower pH, more neutralized zeta potential, and an increased affinity for fibronectin than nonemulsified M brumae. Mice treated with the olive oil-suspended M brumae had a significantly higher systemic immune response.

“These results highlight the potential of the olive oil-based emulsion as a promising delivery vehicle for the mycobacterial treatment of bladder cancer,” said Esther Julián, a professor in the Department of Genetics and Microbiology at the Universitat Autònoma de Barcelona, Barcelona, Spain, and senior author of the study.


1. Noguera-Ortega E, Blanco-Cabra N, Rabanal RM, et al. Mycobacteria emulsified in olive oil-in-water trigger a robust immune response in bladder cancer treatment. Scientific Reports. 2016 Jun 6. doi:10.1038/srep27232. [Epub ahead of print]