Is pneumonia a harmful bacteria or benificial bacteria?

Pneumonia is an infection of the lungs, usually caused by bacteria. Some types of bacteria that can cause pneumonia are harmful, while others are beneficial. Harmful bacteria, such as Streptococcus pneumoniae and Staphylococcus aureus, can cause serious illness and even death. Beneficial bacteria, such as Lactobacillus and Bifidobacterium, help to keep the lungs healthy and free of infection.