Question: what are the causes of pneumonia in babies?
Answer: Streptococcus pneumoniae.
Mycoplasma pneumonia. This often causes a mild form of the illness called walking pneumonia.
Group B streptococcus.
Staphylococcus aureus.
Respiratory syncytial virus (RSV). ... 
Parainfluenza virus.
Influenza virus.
Adenovirus.