Lobar pneumonia is caused predominantly by:
Most cases of lobar pneumonia are caused by S. pneumoniae (reclassification of the pneumococcus). Streptococcal or pneumococcal pneumonia involves one or more lobes and is often seen in alcoholics or debilitated persons.
Klebsiella pneumoniae
Staphylococcus pyogenes
Haemophilus influenzae
Streptococcus pneumoniae