<prompt> Lobar pneumonia is caused predominantly by:Klebsiella pneumoniaeStaphylococcus pyogenesHaemophilus influenzaeStreptococcus pneumoniae  <response>: 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. 