Causes

Pneumonia

Major causes of pneumonia include:

• Mycoplasmas: the smallest free-living organisms that cause disease
• Viruses
• Bacteria: Streptococcus, or strep throat, is the most common cause of bacterial pneumonia

Other causes:

• Pneumocystis carinii, a fungus that causes pneumonia in many people with AIDS
• Inhaled food, liquid, gases, dust or fungi
• Spirochete: causes Rocky Mountain spotted fever, Q fever and typhus, which may all affect the lungs
• Tuberculosis

Bronchitis

Usually acute bronchitis is caused by viruses, often the same virus that causes colds, and may happen after a cold or other respiratory infection.

Major causes of chronic bronchitis also include:

• Tobacco smoke
• Pollutants
• Dust
• Bacteria

More on Pneumonia and Bronchitis

	What Factors Can Increase My Risk of Getting Pneumonia and Bronchitis?
	Tracking Respiratory Infections

In the Encyclopedia:

	Bronchodilators
	Bronchitis
	Chronic obstructive lung disease
	Cough
	Emphysema

Pneumonia Symptoms

	Fever
	Chills
	Cough
	Rapid breathing
	Wheezing
	Chest or abdominal pain
	Loss of appetite
	Exhaustion
	Vomiting
	Bronchitis Symptoms
	Thick white, yellow or greenish mucus
	Headache
	Chills
	Fever
	Shortness of breath
	Soreness/tightness in the chest
	Wheezing

This article was reviewed and updated June 2007.