An antibacterial virus, also known as a phage (5 letters), is a virus that infects and replicates within bacteria. Phages are the most abundant biological entities on Earth and can be used to treat bacterial infections. DIAL (4 letters) is an antibacterial soap that contains certain chemicals that can kill bacteria. Sulfa (5 letters) is an antibiotic drug that is used to treat bacterial infections. It works by inhibiting the growth of bacteria.