Bronchitis should be treated, if it is left untreated, it can lead to pneumonia. Bronchitis is an infection of the airways that leads to your lungs. Pneumonia is an infection that can be located inside on or both of your lungs. There are different types of pneumonia: • Bacterial pneumonia Which is caused by the bacteria Streptococcus, Chlamydophila, or Legionella. • Viral pneumonia Viral pneumonia is caused by respiratory viruses. • Mycoplasma pneumonia Organisms which are neither bacterial or viral, cause mycoplasma pneumonia. • Fungal pneumonia Which can be caused by fungi from soil or bird droppings. Individuals can develop it if you are exposed to and inhale large quantities of the fungi. Viral or Bacterial bronchitis that goes untreated can turn into a viral or bacterial pneumonia quickly.