Immunology in bacteriology studies how the immune system defends the body against bacterial infections. It focuses on the roles of innate immunity (like phagocytes and inflammation) and adaptive immunity (such as antibodies and memory cells). Bacterial components like toxins, capsules, and surface proteins can trigger immune responses. Some bacteria evade immunity through strategies like antigenic variation or biofilm formation. Understanding these mechanisms helps in developing effective vaccines and immunotherapies. Serological tests detect antibodies to diagnose bacterial infections. Immune responses also guide the choice of treatments, including antibiotics. This field is vital for preventing and controlling bacterial diseases.