Necrotizing pneumonia

Pneumonia is an inflammatory condition of the lung affecting primarily the small air sacs known as alveoli. Typically symptoms include some combination of productive or dry cough, chest pain, fever, and trouble breathing. Severity is variable. Pneumonia is usually caused by infection with viruses or bacteria and less commonly by other microorganisms, certain medications and conditions such as autoimmune diseases. Risk factors include other lung diseases such as cystic fibrosis, COPD, and asthma, diabetes, heart failure, a history of smoking, a poor ability to cough such as following a stroke, or a weak immune system. Diagnosis is often based on the symptoms and physical examination. Chest X-ray, blood tests, and culture of the sputum may help confirm the diagnosis. The disease may be classified by where it was acquired with community, hospital, or health care associated pneumonia. Vaccines to prevent certain types of pneumonia are available. Other methods of prevention include handwashing and not smoking. Treatment depends on the underlying cause. Pneumonia believed to be due to bacteria is treated with antibiotics. If the pneumonia is severe, the affected person is generally hospitalized. Oxygen therapy may be used if oxygen levels are low. Pneumonia affects approximately 450 million people globally (7% of the population) and results in about 4 million deaths per year. Pneumonia was regarded by William Osler in the 19th century as 'the captain of the men of death'. With the introduction of antibiotics and vaccines in the 20th century, survival improved. Nevertheless, in developing countries, and among the very old, the very young, and the chronically ill, pneumonia remains a leading cause of death. Pneumonia often shortens suffering among those already close to death and has thus been called 'the old man's friend'. People with infectious pneumonia often have a productive cough, fever accompanied by shaking chills, shortness of breath, sharp or stabbing chest pain during deep breaths, and an increased rate of breathing. In elderly people, confusion may be the most prominent sign. The typical signs and symptoms in children under five are fever, cough, and fast or difficult breathing. Fever is not very specific, as it occurs in many other common illnesses and may be absent in those with severe disease, malnutrition or in the elderly. In addition, a cough is frequently absent in children less than 2 months old. More severe signs and symptoms in children may include blue-tinged skin, unwillingness to drink, convulsions, ongoing vomiting, extremes of temperature, or a decreased level of consciousness. Bacterial and viral cases of pneumonia usually result in similar symptoms. Some causes are associated with classic, but non-specific, clinical characteristics. Pneumonia caused by Legionella may occur with abdominal pain, diarrhea, or confusion. Pneumonia caused by Streptococcus pneumoniae is associated with rusty colored sputum. Pneumonia caused by Klebsiella may have bloody sputum often described as 'currant jelly'. Bloody sputum (known as hemoptysis) may also occur with tuberculosis, Gram-negative pneumonia, lung abscesses and more commonly acute bronchitis. Pneumonia caused by Mycoplasma pneumoniae may occur in association with swelling of the lymph nodes in the neck, joint pain, or a middle ear infection. Viral pneumonia presents more commonly with wheezing than bacterial pneumonia. Pneumonia was historically divided into 'typical' and 'atypical' based on the belief that the presentation predicted the underlying cause. However, evidence has not supported this distinction, therefore it is no longer emphasized. Pneumonia is due to infections caused primarily by bacteria or viruses and less commonly by fungi and parasites. Although there are over 100 strains of infectious agents identified, only a few are responsible for the majority of the cases. Mixed infections with both viruses and bacteria may occur in roughly 45% of infections in children and 15% of infections in adults. A causative agent may not be isolated in approximately half of cases despite careful testing.