Bacterial pneumonia is caused by an infection with bacteria. The infection results in inflammation and swelling of the lung, which causes fluid to collect in the lungs. The fluid blocks oxygen from passing into the bloodstream.

The most common bacteria that cause pneumonia include:

• Chlamydia:
• 1 out 10 cases of pneumonia in the US are chlamydia pneumonia
• Streptococcus:
• Streptococcus pneumonia is the most common cause of community-acquired pneumonia
• Mycoplasma
• Can cause atypical pneumonia

Additional bacteria that cause pneumonia include:

• Haemophilus influenza
• Causes haemophilus pneumonia
• Staphylococcus aureus
• Most serious form is caused by MRSA
• Klebsiella pneumoniae
• May cause lung abscess
• More common in alcoholics
• Legionnaire's disease
• Tuberculosis