Flagellated bacteria used as bio-actuators may prove to be efficient propulsion mechanisms for future hybrid medical nanorobots when operating in the microvasculature. Here, we briefly describe a medical interventional procedure where flagellated bacteria and more specifically MC-1 Magnetotactic Bacteria (MTB) can be used to propel and steer micro-devices and nanorobots under computer control to reach remote locations in the human body. In particular, we show through experimental results the potential of using MTB-tagged robots to deliver therapeutic agents to tumors even the ones located in deep regions of the human body. We also show that such bacterial nanorobots can be tracked inside the human body for enhanced targeting under computer guidance using MRI as imaging modality. MTB can not only be guided and controlled directly towards a specific target, but we also show experimentally that these flagellated bacterial nanorobots can be propelled and steered in vivo deeply through the interstitial region of a tumor. The targeting efficacy is increased when combined with larger ferromagnetic micro-carriers being propelled by magnetic gradients generated by a MRI platform to carry and release nanorobots propelled by a single flagellated bacterium near the arteriocapillar entry. Based on the experimental data obtained and the experience gathered during several experiments conducted in vivo with this new approach, a general medical interventional procedure is briefly described here in a biomedical engineering context.