Bacterial pneumonia overview

Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org] Phone:617-632-7753; Philip Marcus, M.D., M.P.H.[mailto:pmarcus192@aol.com]

Overview
Bacterial pneumonia is an infection of the lungs by bacteria.

Streptococcus pneumoniae is the most common bacterial cause of pneumonia in all age groups except newborn infants. Streptococcus pneumoniae is a Gram-positive bacteria which often lives in the throat of people who do not have pneumonia. Another important Gram-positive cause of pneumonia is Staphylococcus aureus.

Gram-negative bacteria are seen less frequently; Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli , Pseudomonas aeruginosa and Moraxella catarrhalis are the most common. These bacteria often live in the gut and enter the lungs when contents of the gut (such as vomit) are inhaled.

The "atypical" bacteria are Coxiella burnetti, Chlamydophila pneumoniae, Mycoplasma pneumoniae , and Legionella pneumophila. They are "atypical" because they commonly affect teenagers and young adults, are less severe, and require different antibiotics than typical bacteria such as Streptococcus pneumoniae.