If you do not seek out medical treatment for your bronchitis, even though it can go away on its own, it may turn into pneumonia. Pneumonia is an infection that is caused in either one or both sides of your lungs. If left untreated, the infection will then travel from the airways into your lungs which may lead to pneumonia. There are four different types of pneumonia that you can get if you leave bronchitis untreated. They are: • Bacterial pneumonia • Viral pneumonia • Mycoplasma pneumonia • Fungal pneumonia Untreated viral or bacterial bronchitis can easily turn into a viral or bacterial pneumonia.