A portion of a treatment device for treating bacteria may be coupled with the bacteria through direct or indirect contact. Mechanical stress energy and electromagnetic energy are generated with the treatment device, and are transmitted from the treatment device to the bacteria during the coupling. The bacteria are treated with both the mechanical stress energy and the electromagnetic energy to produce a killing effect on the bacteria. A treatment device may include a mechanical stress energy emitting portion, an electromagnetic energy emitting portion, and a contacting portion for coupling into direct or indirect contact with the bacteria and transmitting mechanical stress energy to the bacteria during the coupling. The mechanical stress energy emitting portion and the electromagnetic energy emitting portion are operable to treat the bacteria with a combination of mechanical stress energy and electromagnetic energy to produce a killing effect on the bacteria.