Bacterial pneumonia is an acute inflammation and consolidation (exudate fills alveoli) of lung tissue caused by bacteria.



Pneumonias may be classified according to etiology, host reaction or gross anatomic distribution of the inflammation.

Grossly, in lobar pneumonia the lung appears red and consolidated (red hepatization), followed by grey-white appearance (grey hepatization) due to lysis of RBC's , followed by either complete resolution or fibrosis 

Micro: All bacterial pneumonias are characterized by presence of neutrophils in air spaces and small bronchioles


Varied and many. Culture and sensitivity results, extent of involvement and host resistance are much more important than histologic changes .

Etiology of infectious pneumonia

Clinical picture

Acute onset of fever, cough, chills, pleuritic pain and shortness of breath.

Intensity varies with the etiological agent.

Unique synptoms depending on the infectious agent Eg 


Hypoxia secondary V/Q mismatch.

The possible outcomes of pneumonia?

Gram positive bacilli
Bacteria A93-21