A transform domain digital image watermarking technique is proposed using bacterial foraging optimization (BFO) for telemedicine applications. To make a trade-off between robustness, imperceptibility, and authenticity is a significant focus of our work. The field of telemedicine is one of the critical areas for an intruder to make unwanted changes. The size of medical data is exponentially increasing since the pandemic. So, the security of medical data is also a big concern. One of the most important techniques to safeguard medical data is image watermarking. The digital imaging and communications in medical images of liver ultrasound are taken as input host images. Peak signal-to-noise ratio, Kullback–Leibler distance, and root-mean-square difference are used for BFO. The proposed BacterialWmark technique shows a significant improvement in robustness and imperceptibility compared with other existing techniques. The computational complexity of the proposed work is also less. The authentication of the watermarked image is successfully executed as the features are perfectly matched with the aid of the MinEigen algorithm. So, the BacterialWmark algorithm can be used in the field of telemedicine efficiently.