Pneumonia is an illness in which the small, air-filled sacs in the lungs (alveoli) responsible for absorbing oxygen from the atmosphere are flooded with fluid. Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, or parasites. Pneumonia may also result from chemical or physical irritation of the lungs.
Symptoms associated with pneumonia include cough, chest pain, fever, and difficulty breathing. Diagnostic tools include X-rays and examination of the sputum. Treatment depends on the cause of pneumonia; bacterial pneumonia is treated with antibiotics.
Pneumonia is a common illness, occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically ill. Vaccines to prevent certain types of pneumonia are available. The prognosis for an individual depends on the type of pneumonia, the correct treatment, any complications, and his or her underlying health. Pneumonia may occur as the result of another medical illness, such as lung cancer or alcohol abuse.
http://img44.imageshack.us/img44/7066/diagram14pw.jpg
Symptoms
People with infectious pneumonia often have a cough that produces greenish or yellow sputum and a high fever that may be accompanied by shaking chills. Shortness of breath is also common, as is pleuritic chest pain, a sharp or stabbing pain, either felt or worse during deep breaths or coughs. People with pneumonia may cough up blood, experience headaches, or develop sweaty and clammy skin. Other symptoms may include loss of appetite, fatigue, blueness of the skin, nausea, vomiting, and joint pains or muscle aches. Less common forms of pneumonia can cause a variety of other symptoms. For instance, pneumonia caused by Legionella may cause abdominal pain and diarrhea, while pneumonia caused by tuberculosis or Pneumocystis may cause only weight loss and night sweats. In elderly people the manifestations of pneumonia may not be typical. Instead, they may develop new or worsening confusion or may experience unsteadiness leading to falls. Infants with pneumonia may have many of the symptoms above, but often they are simply sleepy or have decreased appetite.
Diagnosis
To diagnose pneumonia, health care providers rely on a patient's symptoms and findings from physical examination. Information from chest x-rays, blood tests, and sputum cultures may also be helpful. The chest x-ray is typically used for diagnosis in hospitals and some clinics with x-ray facilities. However, in a community setting (general practice), pneumonia is usually diagnosed on the basis of symptoms and physical examination alone. Diagnosing pneumonia can be difficult in some people, especially those who have other illnesses. Occasionally a chest CT scan or other tests may be needed to distinguish pneumonia from other illnesses.
Physical examination
Individuals with symptoms of pneumonia need medical evaluation. Physical examination by a health care provider may reveal fever or sometimes low body temperature, an increased respiratory rate, low blood pressure, a fast heart rate, or a low amount of oxygen in the blood, as indicated by pulse oxymetry or blood gas analysis. People who are struggling to breathe, confused, or who have a blue-tinged skin require immediate attention.
Listening (auscultation) to the lungs with a stethoscope can reveal several things. A lack of normal breath sounds, the presence of crackling sounds (rales), or increased loudness of whispered speech (whispered pectoriloquy) can identify areas of the lung which are stiff and full of fluid (called "consolidation"). The examiner may also feel the way the chest expands (palpation) and tap the chest wall (percussion) to further localize consolidation. The examiner may also palpate for increased vibration of the chest when speaking (tactile fremitus).
http://img44.imageshack.us/img44/2351/xray7sv.jpg
Chest X-rays, sputum cultures and other tests
Pneumonia as seen on chest x-ray. A: Normal chest x-ray. B: Abnormal chest x-ray with shadowing from pneumonia in the right lung (left side of image).An important test for detecting pneumonia in unclear situations is a chest x-ray. Chest x-rays can reveal areas of opacity (seen as white) which represent consolidation. Although a normal chest x-ray makes pneumonia less likely, pneumonia is sometimes not seen on x-rays because the disease is either in its initial stages or because it involves a part of the lung not easily seen by x-ray. In some cases, chest CT (computed tomography) can reveal pneumonia which is not seen on chest x-ray. However, x-rays can be misleading, because other problems, like lung scarring and congestive heart failure, can mimic pneumonia on x-ray. [2] Chest x-rays are also used to evaluate for complications of pneumonia.
If an individual is not getting better with antibiotics, or if the health care provider has concerns about the diagnosis, a culture of the person's sputum may be requested. Sputum cultures generally take at least two to three days, so they are mainly used to confirm that the infection is sensitive to an antibiotic that has already been started. A blood sample may similarly be cultured to look for infection in the blood (blood culture). Any bacteria identified are then tested to see which antibiotics will be most effective.
A complete blood count may show a high white blood cell count, indicating the presence of an infection or inflammation. In some people with immune system problems, the white blood cell count may appear deceptively normal. Blood tests may be used to evaluate kidney function (important when prescribing certain antibiotics) or to look for low blood sodium. Low blood sodium in pneumonia is thought to be due to extra anti-diuretic hormone produced when the lungs are diseased. Specific blood serology tests for other bacteria (Mycoplasma, Legionella and Chlamydophila) and a urine test for Legionella antigen are available. Respiratory secretions can also be tested for the presence of viruses such as influenza, respiratory syncytial virus, and adenovirus.
Although over one hundred microorganisms can cause pneumonia, only a few of them are responsible for most cases. The most common causes of pneumonia are viruses and several types of bacteria: Streptococcus pneumoniae, Gram-negative bacteria and "atypical" bacteria. The terms "Gram-positive" and "Gram-negative" refer to the bacteria's color (purple or red, respectively) when stained using a process called the Gram stain. Less common causes of pneumonia include fungi and irritants, as discussed below.
Streptococcus pneumoniae, often called "pneumococcus", is the most common bacterial cause of pneumonia in all age groups except newborn infants. This is a Gram-positive bacteria which often lives in the throats of people who do not have pneumonia. Another important Gram-positive cause of pneumonia is Staphylococcus aureus. Gram-negative bacteria cause pneumonia less frequently than gram-positive bacteria. Some of the gram-negative bacteria that cause pneumonia include Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Moraxella catarrhalis. These bacteria often live in the stomach or intestines and may enter the lungs if vomit is inhaled. The "atypical" bacteria which cause pneumonia include Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila. They are called "atypical" because they commonly affect healthier people, may be less severe, and usually require different antibiotics than bacteria such as Streptococcus pneumoniae.
Viral pneumonia is commonly caused by viruses such as influenza virus, respiratory syncytial virus (RSV), adenovirus, and metapneumovirus. Herpes simplex virus is a rare cause of pneumonia except in newborns. Although viral pneumonia is usually less severe than bacterial pneumonia, it can damage the lungs and may allow bacteria to cause a more serious infection.
Fungi are uncommon causes of pneumonia which may occur in individuals with immune system problems due to AIDS, immunosuppresive drugs, or other medical problems. Fungal pneumonia is most often caused by Histoplasma capsulatum, Cryptococcus neoformans, and Coccidioides immitis. Histoplasmosis is most common in the Mississippi River basin and Coccidioides is most common in the southwestern United States. Other important causes of pneumonia in people with impaired immune systems include the fungus Pneumocystis jiroveci, the atypical bacterium Mycobacterium avium, and the virus cytomegalovirus (CMV).
Not all pneumonias are caused by infections. Eosinophilic pneumonia, chemical pneumonia, and bronchiolitis obliterans organizing pneumonia (BOOP) each have unique characteristics covered in their individual articles.
Types of pneumonia
There are many different ways to classify infectious pneumonia. Early scientists first classified pneumonias using the various anatomic changes visible in the lungs during autopsies. Later, as more became known about the microorganisms causing pneumonia, a microbiologic classification arose. With the advent of x-rays, a radiological classification was developed. Another important classification system used for pneumonia is the combined clinical classification. It combines many factors, including age, risk factors for certain microorganisms, the person's underlying health, and whether he or she has recently been hospitalized. Finally, there are classification systems for other types of pneumonia.
Anatomic classification
A lobar pneumonia is an infection that only involves a single lobe, or section, of a lung. Lobar pneumonia is often due to Streptococcus pneumoniae. Anatomic changes in the affected part of the lung can be seen during autopsy. Multilobar pneumonia involves more than one lobe, and it often is a more severe illness than lobar pneumonia. Interstitial pneumonia involves the areas in between the alveoli, and it may be called "interstitial pneumonitis." Interstitial pneumonia is more likely to be caused by viruses or by atypical bacteria.
Radiologic classification
The discovery of x-rays made it possible to determinine the anatomic type of pneumonia without direct examination of the lungs at autopsy. Early investigators distinguished between typical lobar pneumonia and atypical (e.g. Chlamydophila) or viral pneumonia using the location, distribution, and appearance of the opacities they saw on chest x-rays. Certain x-ray findings can be used to help predict the course of illness, although it is not possible to clearly determine the microbiologic cause of a pneumonia based on x-rays alone.
Microbiologic classification
Determining which microorganism is causing an individual's pneumonia is an important step in deciding treatment type and length. Sputum cultures, blood cultures, tests on respiratory secretions, and specific blood tests are used to determine the microbiologic classification. Because such laboratory testing typically takes several days, microbiologic classification is usually not possible at the time of initial diagnosis.
Combined clinical classification
The combined clinical classification attempts to identify all of a person's important risk factors when he or she first comes to medical attention. The goal of this classification scheme is to select appropriate initial treatments before the microbiologic cause of the disease is known. There are two broad categories of pneumonia in this scheme: Community acquired pneumonia and Hospital acquired pneumonia.
Community-acquired pneumonia
Community-acquired pneumonia (CAP) is infectious pneumonia in a person who has not recently been hospitalized. CAP is the most common type of pneumonia, and it is the type experienced by most people who get pneumonia. The most common causes of CAP differ depending on a person's age, but they include Streptococcus pneumoniae, viruses, the atypical bacteria, and Haemophilus influenzae. Overall, Streptococcus pneumoniae is the most common cause of community-acquired pneumonia worldwide. Gram negative bacteria cause CAP in certain at-risk populations. CAP is the fourth most common cause of death in the United Kingdom and the sixth in the United States.
An outdated term, walking pneumonia, has been used to describe a type of community-acquired pneumonia that does not restrict a person's ability to walk. Walking pneumonia is usually caused by a virus or by atypical bacteria.
Hospital-acquired pneumonia
Hospital-acquired pneumonia, also called nosocomial pneumonia, is pneumonia acquired during or after hospitalization for another illness or procedure. The causes, microbiology, treatment and prognosis are different from community-acquired pneumonia. Up to 5% of patients admitted to a hospital for other causes subsequently develop pneumonia. Hospitalized patients may have many risk factors for pneumonia, including mechanical ventilation, prolonged malnutrition, underlying heart and lung diseases, decreased amounts of stomach acid, and immune disturbances. Additionally, the microorganisms a person is exposed to in a hospital are often different from those at home. Hospital-acquired microorganisms may include resistant bacteria such as MRSA, Pseudomonas, Enterobacter, and Serratia. Because individuals with hospital-acquired pneumonia usually have underlying illnesses and are exposed to more dangerous bacteria, it tends to be more deadly than community-acquired pneumonia.
Treatment for pneumonia should ideally be selected based on the causative microorganism and its known antibiotic sensitivity. However, a specific cause for pneumonia is identified in only 50% of people, even after extensive evaluation. Empiric treatment is usually started well before laboratory reports are available because such treatment generally cannot be delayed in any patient with a serious pneumonia. Antibiotics used for hospital-acquired pneumonia include vancomycin, third and fourth generation cephalosporins, carbapenems, fluoroquinolones, and aminoglycosides. Multiple antibiotics are usually administered in combination to cover all the possible causative organisms. Antibiotic choices vary from hospital to hospital because of differences in likely microrganisms and resistance patterns.
Ventilator-associated pneumonia (VAP) is a subset of hospital-acquired pneumonia. VAP is pneumonia which occurs after at least 48 hours of intubation and mechanical ventilation
Other types of pneumonia
Severe acute respiratory syndrome (SARS)
SARS is a highly contagious and deadly type of pneumonia which occurred in 2002 and 2003 after initial outbreaks in China. SARS is caused by the SARS coronavirus, a previously unknown pathogen. The last SARS case was seen in June 2003.
Bronchiolitis obliterans organizing pneumonia (BOOP)
BOOP is caused by inflammation of the small airways of the lungs. It is also known as cryptogenic organizing pneumonitis (COP).
Eosinophilic pneumonia
Eosinophilic pneumonia is invasion of the lung by eosinophils, a particular kind of white blood cell. Eosinophilic pneumonia often occurs in response to infection with a parasite or after exposure to certain types of environmental factors.
Chemical pneumonia
Also known as chemical pneumonitis, chemical pneumonia is caused by chemical toxins such as pesticides which enter the body by inhalation or by skin contact. When the toxic substance is an oil, the pneumonia may be called lipoid pneumonia.
Prevention
There are several ways to prevent infectious pneumonia. Treating underlying illness (such as AIDS) can decrease a person's risk. Smoking cessation is important not only for treatment of any underlying lung disease, but also because cigarette smoke interferes with many of the body's natural defenses against pneumonia.
Vaccination is important in both children and adults. Vaccinations against Haemophilus influenzae and Streptococcus pneumoniae in the first year of life have greatly reduced their role in pneumonia in children. Vaccination of children against Streptococcus pneumoniae has also led to a decreased incidence in adults because many adults acquire infection from children. A vaccine against Streptococcus pneumoniae is also available for adults and is currently recommended for all healthy individuals older than 65 and any adults with emphysema, congestive heart failure, diabetes mellitus, cirrhosis of the liver, alcoholism, cerebrospinal fluid leaks, or who do not have a spleen. A repeat vaccination may also be required after five or ten years.
Influenza vaccines should be given yearly to the same individuals who receive vaccination against Streptococcus pneumoniae. In addition, health care workers, nursing home residents, and pregnant women should receive the vaccine. When an influenza outbreak is occurring, medications such as amantadine, rimantadine, zanamivir, and oseltamivir have been shown to prevent cases of influenza
Epidemiology
Pneumonia is a common illness in all parts of the world. It is a major cause of death among all age groups. In children, the majority of deaths occur in the newborn period, with over two million deaths a year worldwide. In fact, the WHO estimates that one in three newborn infant deaths are due to pneumonia. Mortality decreases with age until late adulthood; elderly individuals are at particular risk for pneumonia and associated mortality.
More cases of pneumonia occur during winter months than during other times of the year. Pneumonia occurs more commonly in males than females and in blacks than Caucasians. Individuals with underlying illnesses such as Alzheimer's disease, cystic fibrosis, emphysema, tobacco smoking, alcoholism, or immune system problems are at increased risk for pneumonia. These individuals are also more likely to have repeated episodes of pneumonia. People who are hospitalized for any reason are also at high risk for pneumonia.
SakuraGuy
ZEROTOHUNDRED.COM
Source: INTERNATIONAL
Symptoms associated with pneumonia include cough, chest pain, fever, and difficulty breathing. Diagnostic tools include X-rays and examination of the sputum. Treatment depends on the cause of pneumonia; bacterial pneumonia is treated with antibiotics.
Pneumonia is a common illness, occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically ill. Vaccines to prevent certain types of pneumonia are available. The prognosis for an individual depends on the type of pneumonia, the correct treatment, any complications, and his or her underlying health. Pneumonia may occur as the result of another medical illness, such as lung cancer or alcohol abuse.
http://img44.imageshack.us/img44/7066/diagram14pw.jpg
Symptoms
People with infectious pneumonia often have a cough that produces greenish or yellow sputum and a high fever that may be accompanied by shaking chills. Shortness of breath is also common, as is pleuritic chest pain, a sharp or stabbing pain, either felt or worse during deep breaths or coughs. People with pneumonia may cough up blood, experience headaches, or develop sweaty and clammy skin. Other symptoms may include loss of appetite, fatigue, blueness of the skin, nausea, vomiting, and joint pains or muscle aches. Less common forms of pneumonia can cause a variety of other symptoms. For instance, pneumonia caused by Legionella may cause abdominal pain and diarrhea, while pneumonia caused by tuberculosis or Pneumocystis may cause only weight loss and night sweats. In elderly people the manifestations of pneumonia may not be typical. Instead, they may develop new or worsening confusion or may experience unsteadiness leading to falls. Infants with pneumonia may have many of the symptoms above, but often they are simply sleepy or have decreased appetite.
Diagnosis
To diagnose pneumonia, health care providers rely on a patient's symptoms and findings from physical examination. Information from chest x-rays, blood tests, and sputum cultures may also be helpful. The chest x-ray is typically used for diagnosis in hospitals and some clinics with x-ray facilities. However, in a community setting (general practice), pneumonia is usually diagnosed on the basis of symptoms and physical examination alone. Diagnosing pneumonia can be difficult in some people, especially those who have other illnesses. Occasionally a chest CT scan or other tests may be needed to distinguish pneumonia from other illnesses.
Physical examination
Individuals with symptoms of pneumonia need medical evaluation. Physical examination by a health care provider may reveal fever or sometimes low body temperature, an increased respiratory rate, low blood pressure, a fast heart rate, or a low amount of oxygen in the blood, as indicated by pulse oxymetry or blood gas analysis. People who are struggling to breathe, confused, or who have a blue-tinged skin require immediate attention.
Listening (auscultation) to the lungs with a stethoscope can reveal several things. A lack of normal breath sounds, the presence of crackling sounds (rales), or increased loudness of whispered speech (whispered pectoriloquy) can identify areas of the lung which are stiff and full of fluid (called "consolidation"). The examiner may also feel the way the chest expands (palpation) and tap the chest wall (percussion) to further localize consolidation. The examiner may also palpate for increased vibration of the chest when speaking (tactile fremitus).
http://img44.imageshack.us/img44/2351/xray7sv.jpg
Chest X-rays, sputum cultures and other tests
Pneumonia as seen on chest x-ray. A: Normal chest x-ray. B: Abnormal chest x-ray with shadowing from pneumonia in the right lung (left side of image).An important test for detecting pneumonia in unclear situations is a chest x-ray. Chest x-rays can reveal areas of opacity (seen as white) which represent consolidation. Although a normal chest x-ray makes pneumonia less likely, pneumonia is sometimes not seen on x-rays because the disease is either in its initial stages or because it involves a part of the lung not easily seen by x-ray. In some cases, chest CT (computed tomography) can reveal pneumonia which is not seen on chest x-ray. However, x-rays can be misleading, because other problems, like lung scarring and congestive heart failure, can mimic pneumonia on x-ray. [2] Chest x-rays are also used to evaluate for complications of pneumonia.
If an individual is not getting better with antibiotics, or if the health care provider has concerns about the diagnosis, a culture of the person's sputum may be requested. Sputum cultures generally take at least two to three days, so they are mainly used to confirm that the infection is sensitive to an antibiotic that has already been started. A blood sample may similarly be cultured to look for infection in the blood (blood culture). Any bacteria identified are then tested to see which antibiotics will be most effective.
A complete blood count may show a high white blood cell count, indicating the presence of an infection or inflammation. In some people with immune system problems, the white blood cell count may appear deceptively normal. Blood tests may be used to evaluate kidney function (important when prescribing certain antibiotics) or to look for low blood sodium. Low blood sodium in pneumonia is thought to be due to extra anti-diuretic hormone produced when the lungs are diseased. Specific blood serology tests for other bacteria (Mycoplasma, Legionella and Chlamydophila) and a urine test for Legionella antigen are available. Respiratory secretions can also be tested for the presence of viruses such as influenza, respiratory syncytial virus, and adenovirus.
Although over one hundred microorganisms can cause pneumonia, only a few of them are responsible for most cases. The most common causes of pneumonia are viruses and several types of bacteria: Streptococcus pneumoniae, Gram-negative bacteria and "atypical" bacteria. The terms "Gram-positive" and "Gram-negative" refer to the bacteria's color (purple or red, respectively) when stained using a process called the Gram stain. Less common causes of pneumonia include fungi and irritants, as discussed below.
Streptococcus pneumoniae, often called "pneumococcus", is the most common bacterial cause of pneumonia in all age groups except newborn infants. This is a Gram-positive bacteria which often lives in the throats of people who do not have pneumonia. Another important Gram-positive cause of pneumonia is Staphylococcus aureus. Gram-negative bacteria cause pneumonia less frequently than gram-positive bacteria. Some of the gram-negative bacteria that cause pneumonia include Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Moraxella catarrhalis. These bacteria often live in the stomach or intestines and may enter the lungs if vomit is inhaled. The "atypical" bacteria which cause pneumonia include Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila. They are called "atypical" because they commonly affect healthier people, may be less severe, and usually require different antibiotics than bacteria such as Streptococcus pneumoniae.
Viral pneumonia is commonly caused by viruses such as influenza virus, respiratory syncytial virus (RSV), adenovirus, and metapneumovirus. Herpes simplex virus is a rare cause of pneumonia except in newborns. Although viral pneumonia is usually less severe than bacterial pneumonia, it can damage the lungs and may allow bacteria to cause a more serious infection.
Fungi are uncommon causes of pneumonia which may occur in individuals with immune system problems due to AIDS, immunosuppresive drugs, or other medical problems. Fungal pneumonia is most often caused by Histoplasma capsulatum, Cryptococcus neoformans, and Coccidioides immitis. Histoplasmosis is most common in the Mississippi River basin and Coccidioides is most common in the southwestern United States. Other important causes of pneumonia in people with impaired immune systems include the fungus Pneumocystis jiroveci, the atypical bacterium Mycobacterium avium, and the virus cytomegalovirus (CMV).
Not all pneumonias are caused by infections. Eosinophilic pneumonia, chemical pneumonia, and bronchiolitis obliterans organizing pneumonia (BOOP) each have unique characteristics covered in their individual articles.
Types of pneumonia
There are many different ways to classify infectious pneumonia. Early scientists first classified pneumonias using the various anatomic changes visible in the lungs during autopsies. Later, as more became known about the microorganisms causing pneumonia, a microbiologic classification arose. With the advent of x-rays, a radiological classification was developed. Another important classification system used for pneumonia is the combined clinical classification. It combines many factors, including age, risk factors for certain microorganisms, the person's underlying health, and whether he or she has recently been hospitalized. Finally, there are classification systems for other types of pneumonia.
Anatomic classification
A lobar pneumonia is an infection that only involves a single lobe, or section, of a lung. Lobar pneumonia is often due to Streptococcus pneumoniae. Anatomic changes in the affected part of the lung can be seen during autopsy. Multilobar pneumonia involves more than one lobe, and it often is a more severe illness than lobar pneumonia. Interstitial pneumonia involves the areas in between the alveoli, and it may be called "interstitial pneumonitis." Interstitial pneumonia is more likely to be caused by viruses or by atypical bacteria.
Radiologic classification
The discovery of x-rays made it possible to determinine the anatomic type of pneumonia without direct examination of the lungs at autopsy. Early investigators distinguished between typical lobar pneumonia and atypical (e.g. Chlamydophila) or viral pneumonia using the location, distribution, and appearance of the opacities they saw on chest x-rays. Certain x-ray findings can be used to help predict the course of illness, although it is not possible to clearly determine the microbiologic cause of a pneumonia based on x-rays alone.
Microbiologic classification
Determining which microorganism is causing an individual's pneumonia is an important step in deciding treatment type and length. Sputum cultures, blood cultures, tests on respiratory secretions, and specific blood tests are used to determine the microbiologic classification. Because such laboratory testing typically takes several days, microbiologic classification is usually not possible at the time of initial diagnosis.
Combined clinical classification
The combined clinical classification attempts to identify all of a person's important risk factors when he or she first comes to medical attention. The goal of this classification scheme is to select appropriate initial treatments before the microbiologic cause of the disease is known. There are two broad categories of pneumonia in this scheme: Community acquired pneumonia and Hospital acquired pneumonia.
Community-acquired pneumonia
Community-acquired pneumonia (CAP) is infectious pneumonia in a person who has not recently been hospitalized. CAP is the most common type of pneumonia, and it is the type experienced by most people who get pneumonia. The most common causes of CAP differ depending on a person's age, but they include Streptococcus pneumoniae, viruses, the atypical bacteria, and Haemophilus influenzae. Overall, Streptococcus pneumoniae is the most common cause of community-acquired pneumonia worldwide. Gram negative bacteria cause CAP in certain at-risk populations. CAP is the fourth most common cause of death in the United Kingdom and the sixth in the United States.
An outdated term, walking pneumonia, has been used to describe a type of community-acquired pneumonia that does not restrict a person's ability to walk. Walking pneumonia is usually caused by a virus or by atypical bacteria.
Hospital-acquired pneumonia
Hospital-acquired pneumonia, also called nosocomial pneumonia, is pneumonia acquired during or after hospitalization for another illness or procedure. The causes, microbiology, treatment and prognosis are different from community-acquired pneumonia. Up to 5% of patients admitted to a hospital for other causes subsequently develop pneumonia. Hospitalized patients may have many risk factors for pneumonia, including mechanical ventilation, prolonged malnutrition, underlying heart and lung diseases, decreased amounts of stomach acid, and immune disturbances. Additionally, the microorganisms a person is exposed to in a hospital are often different from those at home. Hospital-acquired microorganisms may include resistant bacteria such as MRSA, Pseudomonas, Enterobacter, and Serratia. Because individuals with hospital-acquired pneumonia usually have underlying illnesses and are exposed to more dangerous bacteria, it tends to be more deadly than community-acquired pneumonia.
Treatment for pneumonia should ideally be selected based on the causative microorganism and its known antibiotic sensitivity. However, a specific cause for pneumonia is identified in only 50% of people, even after extensive evaluation. Empiric treatment is usually started well before laboratory reports are available because such treatment generally cannot be delayed in any patient with a serious pneumonia. Antibiotics used for hospital-acquired pneumonia include vancomycin, third and fourth generation cephalosporins, carbapenems, fluoroquinolones, and aminoglycosides. Multiple antibiotics are usually administered in combination to cover all the possible causative organisms. Antibiotic choices vary from hospital to hospital because of differences in likely microrganisms and resistance patterns.
Ventilator-associated pneumonia (VAP) is a subset of hospital-acquired pneumonia. VAP is pneumonia which occurs after at least 48 hours of intubation and mechanical ventilation
Other types of pneumonia
Severe acute respiratory syndrome (SARS)
SARS is a highly contagious and deadly type of pneumonia which occurred in 2002 and 2003 after initial outbreaks in China. SARS is caused by the SARS coronavirus, a previously unknown pathogen. The last SARS case was seen in June 2003.
Bronchiolitis obliterans organizing pneumonia (BOOP)
BOOP is caused by inflammation of the small airways of the lungs. It is also known as cryptogenic organizing pneumonitis (COP).
Eosinophilic pneumonia
Eosinophilic pneumonia is invasion of the lung by eosinophils, a particular kind of white blood cell. Eosinophilic pneumonia often occurs in response to infection with a parasite or after exposure to certain types of environmental factors.
Chemical pneumonia
Also known as chemical pneumonitis, chemical pneumonia is caused by chemical toxins such as pesticides which enter the body by inhalation or by skin contact. When the toxic substance is an oil, the pneumonia may be called lipoid pneumonia.
Prevention
There are several ways to prevent infectious pneumonia. Treating underlying illness (such as AIDS) can decrease a person's risk. Smoking cessation is important not only for treatment of any underlying lung disease, but also because cigarette smoke interferes with many of the body's natural defenses against pneumonia.
Vaccination is important in both children and adults. Vaccinations against Haemophilus influenzae and Streptococcus pneumoniae in the first year of life have greatly reduced their role in pneumonia in children. Vaccination of children against Streptococcus pneumoniae has also led to a decreased incidence in adults because many adults acquire infection from children. A vaccine against Streptococcus pneumoniae is also available for adults and is currently recommended for all healthy individuals older than 65 and any adults with emphysema, congestive heart failure, diabetes mellitus, cirrhosis of the liver, alcoholism, cerebrospinal fluid leaks, or who do not have a spleen. A repeat vaccination may also be required after five or ten years.
Influenza vaccines should be given yearly to the same individuals who receive vaccination against Streptococcus pneumoniae. In addition, health care workers, nursing home residents, and pregnant women should receive the vaccine. When an influenza outbreak is occurring, medications such as amantadine, rimantadine, zanamivir, and oseltamivir have been shown to prevent cases of influenza
Epidemiology
Pneumonia is a common illness in all parts of the world. It is a major cause of death among all age groups. In children, the majority of deaths occur in the newborn period, with over two million deaths a year worldwide. In fact, the WHO estimates that one in three newborn infant deaths are due to pneumonia. Mortality decreases with age until late adulthood; elderly individuals are at particular risk for pneumonia and associated mortality.
More cases of pneumonia occur during winter months than during other times of the year. Pneumonia occurs more commonly in males than females and in blacks than Caucasians. Individuals with underlying illnesses such as Alzheimer's disease, cystic fibrosis, emphysema, tobacco smoking, alcoholism, or immune system problems are at increased risk for pneumonia. These individuals are also more likely to have repeated episodes of pneumonia. People who are hospitalized for any reason are also at high risk for pneumonia.
SakuraGuy
ZEROTOHUNDRED.COM
Source: INTERNATIONAL
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