What is pneumonia?
Pneumonia is an infection of the lungs. It involves the tiny air sacs, called alveoli, which are located at the tips of the body’s smallest breathing tubes, called the bronchi. The alveoli are responsible for passing oxygen into the blood. Pneumonia is an inflammation of the lung caused by infection with bacteria, viruses, or other organisms. Pneumonia is usually triggered when a person's defense system is weakened, most often by a simple viral upper respiratory tract infection or a case of
influenza (the flu). Such infections or other triggers do not cause pneumonia directly but they alter the protective blanket of mucous in the lungs (that prevents foreign substances from getting into the lungs), thus encouraging bacterial growth. Other factors can also make specific people susceptible to bacterial growth in the lungs and pneumonia.
Pneumonia affects the lungs in two ways. Lobar pneumonia affects a lobe of the lungs, and bronchial pneumonia can affect patches throughout both lungs. Bacteria are the most common cause of pneumonia in adults who are older than 30 years. Of these, Streptococcus pneumoniae is the most common. Other pathogens include anaerobic bacteria, Staphylococcus aureus, Haemophilus influenzae, Chlamydia pneumoniae, C. psittaci, C. trachomatis, Moraxella (Branhamella) catarrhalis, Legionella pneumophila, Klebsiella pneumoniae, and other gram-negative bacilli. Mycoplasma pneumoniae, a bacteria-like organism, is particularly common in older children and young adults, typically in the spring. Major pulmonary pathogens in infants and children are viruses: respiratory syncytial virus, parainfluenza virus, and influenza A and B viruses. These agents may also cause pneumonia in adults; however, the only common viruses in previously healthy adults are influenza A, occasionally influenza B, and rarely varicella-zoster. Among other agents are higher bacteria including Nocardia and Actinomyces sp; mycobacteria, including Mycobacterium tuberculosis and atypical strains (primarily M. kansasii and M. avium-intracellulare); fungi, including Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Cryptococcus neoformans, Aspergillus fumigatus, and Pneumocystis carinii; and rickettsiae, primarily Coxiella burnetii (Q fever).
The major types of pneumonia are bacterial pneumonia, viral pneumonia, and mycoplasma pneumonia. Others include pneumocystis carinii pneumonia (PCP), which is caused by a fungus, primarily in AIDS patients. Viral pneumonia is less common in normal adults with a fully functioning immune system; however, most pneumonia in the very young is caused by viral infection, including respiratory syncytial virus (RSV). Pneumonia also may be caused by the inhalation of food, liquid, gases or dust, and by fungi. Certain diseases, such as tuberculosis, can cause pneumonia. Aspiration (or inhalation) pneumonia is a swelling and irritation of the lungs caused by breathing in vomit, fumes from such chemicals as bug sprays, pool cleaners, gasoline, or other substances. This kind of pneumonia cannot be spread to other people.
Pneumonia can range from mild to severe, even fatal. The severity depends on the type of organism causing pneumonia as well as age and underlying health. The most common symptoms of pneumonia are shortness of breath; chest pain, especially when breathing in; coughing; shallow, rapid breathing; and fever and chills. Coughs usually bring up mucus, also called sputum. The sputum may even be streaked with blood or pus. In serious cases, the patient’s lips or nail bed will appear blue due to lack of oxygen. Pneumonia can turn deadly, for instance, when inflammation from the disease fills the air spaces within your lungs (alveoli) and interferes with your ability to breathe. In some cases the infection may invade your bloodstream (bacteremia). It can then spread quickly to other organs.
More information on pneumonia
What is pneumonia? - Pneumonia is an infection of the lungs. Pneumonia is an inflammation of the lung caused by infection with bacteria, viruses, or other organisms.
What types of pneumonia are there? - Types of pneumonia are bacterial pneumonia, viral pneumonia, mycoplasma pneumonia, pneumocystis carinii pneumonia, aspiration (or inhalation) pneumonia.
What is walking pneumonia? - Walking pneumonia is pneumonia that is usually mild enough that the child does not have to stay in bed.
What is aspiration pneumonia? - Aspiration pneumonia is an inflammation of the lungs and bronchial tubes caused by inhaling foreign material.
What is bacterial pneumonia? - Bacterial pneumonia is pneumonia caused by bacteria. Streptococcus pneumoniae is the most common cause of bacterial pneumonia.
What is viral pneumonia? - Viral pneumonia is caused by various viruses. Viral pneumonia is usually milder than bacterial pneumonia.
What is bronchial pneumonia? - Bronchial pneumonia is when the pneumonia spreads to several patches in one or both lungs.
What is community-acquired pneumonia? - Community-acquired pneumonia occurs most commonly in very young and very old people.
What is hospital-acquired pneumonia? - Hospital-acquired pneumonia, also called nosocomial pneumonia, is an infection that patients get while they're in the hospital.
What is atypical pneumonia? - Atypical pneumonia is a pneumonia that does not respond to the usual antibiotic treatment.
What causes pneumonia? - Pneumonia is caused by viruses, bacteria, or parasites or other organisms such as Streptococcus pneumoniae.
What're the risk factors for pneumonia? - Alcohol or drug abuse is strongly associated with pneumonia. The elderly and infants and young children are at greater risk of pneumonia.
What're the complications of pneumonia? - Complications of pneumonia that may occur include buildup of fluid in the space between the lung and chest wall.
What are the symptoms of pneumonia? - Symptoms of pneumonia are shortness of breath, chest pain, coughing, shallow, and fever and chills.
How is pneumonia diagnosed? - The diagnosis of pneumonia is usually made from a medical history, a physical examination, and a chest X-ray.
What's the treatment for pneumonia? - Treatment of pneumonia consists of respiratory support, including O2 if indicated, and antibiotics.
How to prevent pneumonia? - Vaccines are available to protect against pneumococcal pneumonia, pneumonia caused by the bacterium.