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Thousands of microorganisms enter the nose daily, including bacteria, viruses, and fungi. Infection from these organisms can cause pneumonia pathophysiology. The most common causes of pneumonia pathophysiology are those caused by bacteria and viruses. After infection, inflammation of the lungs typically occurs and pneumonia usually develops.
A respiratory tract has several ways to help stop infections. Hairs are present in the nose to filter inhaled air. Sneezing and coughing occur as reflex mechanisms to expel harmful products that enter the nose. The presence of friendly bacteria inside the nose also usually prevents harmful organisms from invading and multiplying. When the health of a person is compromised though, these normal defenses of the body usually weaken and allow infection and pneumonia to take root.
The most common pneumonia pathophysiology begins when the defense mechanisms of the body fail. Examples include malnutrition, the presence of chronic diseases, immune deficiencies, and the use of some potent drugs. Smoking, inhalation of corrosive gases, alcohol intake, and genetic disorders also could lead to the infection.
If bacteria or viruses enter the nose and meet no resistance, they typically begin to multiply and eventually enter the lungs. In the lungs, many cells are capable of engulfing the invading organisms and killing them. When the organisms outnumber these cells, other cells of the immune system usually gather in the lungs to help stop the infection. During this process, inflammation and secretions increase, typically resulting in a fever and a cough with sputum production.
The symptoms of pneumonia vary. Some patients show mild symptoms while others will have severe manifestations that can be life-threatening. Early symptoms might include fever and a cough, and could be misconstrued as a simple case of the flu. Continued fever, sweating, coughing, breathing difficulty, chills, headache, fatigue, muscle pains, and chest pains are the common symptoms typically seen as the pneumonia progresses.
Pneumonia pathophysiology usually depends on the infecting organism. Bacterial pneumonia can be caused by Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Moraxella catarrhalis, and Legionella species. Viral pneumonia can be caused by adenoviruses, respiratory syncytial viruses, Influenza A and B viruses, and parainfluenza viruses.
Fungal pneumonia could occur from infection with Histoplasma capsulatum, Coccidioides immitis, Pneumocystis jiroveci, or Cryptococcus neoformans. Infections with fungi are rare. It mostly occurs in patients whose immune systems have been compromised, such as those with acquired immune deficiency syndrome (AIDS).
Some parasites also might invade the lungs and cause parasitic pneumonia. These parasites could include Ascaris lumbricoides, Toxoplasma gondii, and Strongyloides stercoralis. Aspiration pneumonia can happen when stomach contents make its way into the lungs. This mostly occurs in stroke patients who have abnormal swallowing reflexes.