Bacterial pneumonia overview
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Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753; Philip Marcus, M.D., M.P.H.[2]
Overview
Bacterial pneumonia is an infection of the lungs by bacteria.
Streptococcus pneumoniae (J13) 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 (J15.2).
Gram-negative bacteria are seen less frequently; Haemophilus influenzae (J14), Klebsiella pneumoniae(J15.0), Escherichia coli (J15.5), Pseudomonas aeruginosa(J15.1) 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 (J16.0), Mycoplasma pneumoniae (J15.7), 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.
Treatment
Medical Therapy
Antibiotics are the treatment of choice for bacterial pneumonia. The antibiotic choice depends on the nature of the pneumonia, the microorganisms most commonly causing pneumonia in the geographical region, and the immune status and underlying health of the individual. In the United Kingdom, amoxicillin is used as first-line therapy in the vast majority of patients who acquire pneumonia in the community, sometimes with added clarithromycin. In North America, where the "atypical" forms of community-acquired pneumonia are becoming more common, clarithromycin, azithromycin, or fluoroquinolones as single therapy, have displaced the amoxicillin as first-line therapy. Local patterns of antibiotic-resistance should always be considered when initiating pharmacotherapy. In hospitalized individuals or those with immune deficiencies, local guidelines determine the selection of antibiotics. These antibiotics are typically given through an intravenous line.