Pneumonia is an inflammation of the lung caused by infection with bacteria, viruses, and other organisms. Pneumonia is usually triggered when a patient's defense system is weakened, most often by a simple viral upper respiratory tract infection or a case of influenza. Such infections or other triggers do not cause pneumonia directly but they alter the mucous blanket, thus encouraging bacterial growth. Other factors can also make specific people susceptible to bacterial growth and pneumonia.
Cause of pneumonia
Bacteria are the most common causes of pneumonia, but these infections can also be caused by other microbial organisms. It is often impossible to identify the specific culprit. The most common cause of pneumonia is the gram-positive bacterium Streptococcus pneumoniae (also called S. pneumoniae or pneumococcal pneumonia ). The most common gram-negative species causing pneumonia is Haemophilus influenzae (generally occurring in patients with chronic lung disease, older patients, and alcoholics).
Atypical pneumonias are generally caused by tiny nonbacterial organisms called Mycoplasma or Chlamydia pneumoniae and produce mild symptoms with a dry cough. Viruses that can cause or lead to pneumonia include influenza, respiratory syncytial virus (RSV), herpes simplex virus, varicella-zoster (the cause of chicken pox), and adenovirus.
PNEUMONIA - Symptoms of Common Pneumonias
The symptoms of bacterial pneumonia develop abruptly and may include chest pain, fever, shaking, chills, shortness of breath, and rapid breathing and heart beat.
Symptoms of pneumonia indicating a medical emergency include high fever, a rapid heart rate, low blood pressure, bluish-skin, and mental confusion.
Coughing up sputum containing pus or blood is an indication of serious infection.
Severe abdominal pain may accompany pneumonia occurring in the lower lobes of the lung.
In advanced cases, the patient's skin may become bluish (cyanotic), breathing may become labored and heavy, and the patient may become confused.
Symptoms in the Elderly. It is important to note that older people may have fewer or different symptoms than younger people have. An elderly person who experiences even a minor cough and weakness for more than a day should seek medical help. Some may exhibit confusion, lethargy, and general deterioration.
Symptoms of Pneumonia Causes by Anaerobic Bacteria
People with pneumonia caused by anaerobic bacteria such as Bacteroides, which can produce abscesses, often have prolonged fever and productive cough, frequently showing blood in the sputum, which indicates necrosis (tissue death) in the lung. About a third of these patients experience weight loss.
Symptoms of Atypical Pneumonia
General Symptoms for Atypical Pneumonias. Atypical nonbacterial pneumonia is most commonly caused by Mycoplasma and usually appears in children and young adults.
Symptoms progress gradually, often beginning with general flu-like symptoms, such as fatigue, fever, weakness, headache, nasal discharge, sore throat, ear ache, and stomach and intestinal distress.
Vague pain under and around the breast bone may occur, but the severe chest pain associated with typical bacterial pneumonia is uncommon.
Patients may experience a severe hacking cough, but it usually does not produce sputum.
Symptoms of Legionnaire's Disease
Symptoms of Legionnaire's disease usually evolve more rapidly and include high fever, a dry cough, and shortness of breath, often accompanied by headache, muscle pains, fatigue, gastrointestinal problems, and mental confusion.