Pathogenic bacteria are harmful microorganisms that can cause diseases in humans, animals, and plants. These tiny organisms invade the body, multiply, and produce toxins that disrupt normal bodily functions. Common examples of pathogenic bacteria include Escherichia coli, which can lead to food poisoning, and Streptococcus pneumoniae, responsible for pneumonia. To protect ourselves from these harmful bacteria, good hygiene practices are essential. Washing hands regularly, cooking food thoroughly, and keeping surfaces clean can help prevent infections. Vaccines also play a crucial role in defending against certain bacterial diseases, such as those caused by Haemophilus influenzae.