As an extremely simple and efficiency way to kill Gram-positive, -negative, -multidrug resistant bacteria, and in particular methicillin-resistant Staphylococcus aureus, gold nanoparticles were grown self-assembling to yield gold nanoshells on the surface of bacteria (bacteria coated with gold nanoshells or bacterial nanomaterials) by the solution contained gold ion but no adding reductant. The bacteria with gold nanoshells still kept their vitality and mobility for weeks. Due to gold with the high efficiently to convert absorbed radiation into heat for serving as photothermal therapeutic agents, enabled the bacteria coated with gold nanoshells acted as photothermal agents to kill bacteria efficiently. As a result, these bacterial nanomaterials showed impressive photothermolytic efficacy to reduce the viability of bacteria with laser irradiation and an excellent ability to emit photoluminescence after laser irradiation which was generated from the dead bacteria coated with bacterial nanomaterials. The stronger photoluminescence was emitted, the more bacteria were killed. Moreover, the photoluminescence which was able to sustain femtosecond laser exposure, keep luminescence emitted and prevent from photobleaching was still generated after being exposed for hours. It is very eligible to act as optical contrast agents. As a result, these nanomaterials were definitely able to serve as brand-new contrast agents or indicators to determine viability, track and localize bacteria in clinical applications.