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Pneumonia
Other namesPneumonitis
Chest radiograph in influensa and H influenzae, posteroanterior, annotated.jpg
Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)
Pronunciation
SpecialtyPulmonology, Infectious disease
SymptomsCough, difficulty breathing, rapid breathing, fever[1]
DurationFew weeks[2]
CausesBacteria, virus, aspiration[3][4]
Risk factorsCystic fibrosis, COPD, sickle cell disease, asthma, diabetes, heart failure, history of smoking, older age[5][6][7]
Diagnostic methodBased on symptoms, chest X-ray[8]
Differential diagnosisCOPD, asthma, pulmonary edema, pulmonary embolism[9]
PreventionVaccines, handwashing, not smoking[10]
MedicationAntibiotics, antivirals, oxygen therapy[11][12]
Frequency450 million (7%) per year[12][13]
DeathsFour million per year[12][13]

Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.[3][14] Symptoms typically include some combination of productive or dry cough, chest pain, fever and difficulty breathing.[1] The severity of the condition is variable.

inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.[3][14] Symptoms typically include some combination of productive or dry cough, chest pain, fever and difficulty breathing.[1] The severity of the condition is variable.[1] Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms.[a] Identifying the responsible pathogen can be difficult. Diagnosis is often based on symptoms and physical examination.[8] Chest X-rays, blood tests, and culture of the sputum may help confirm the diagnosis.[8] The disease may be classified by where it was acquired, such as community- or hospital-acquired or healthcare-associated pneumonia.[17]

Risk factors for pneumonia include cystic fibrosis, chronic obstructive pulmonary disease (COPD), sickle cell disease, asthma, diabetes, heart failure, a history of smoking, a poor ability to cough (such as following a stroke), and a weak immune system.[5][7]

Vaccines to prevent certain types of pneumonia (such as those caused by Streptococcus pneumoniae bacteria or that linked to influenza) are available.[10] Other methods of prevention include hand washing to prevent infection, and not smoking.[10]

Treatment depends on the underlying cause.[18] Pneumonia believed to be due to bacteria is treated with antibiotics.[11] If the pneumonia is severe, the affected person is generally hospitalized.[18] Oxygen therapy may be used if oxygen levels are low.[11]

Each year, pneumonia affects about 450 million people globally (7% of the population) and results in about 4 million deaths.[12][13] With the introduction of antibiotics and vaccines in the 20th century, survival has greatly improved.[12] Nevertheless, pneumonia remains a leading cause of death in developing countries, and also among the very old, the very young, and the chronically ill.[12][19] Pneumonia often shortens the period of suffering among those already close to death and has thus been called "the old man's friend".[20]

Video summary (script)
  • Right middle lobe pneumonia in a child as seen on plain X ray

  • Right middle lobe pneumonia in a child as seen on plain X ray

    Microbiology

    In people managed in the community, determining the causative agent is not cost-effective and typically does not alter management.[22] For people who do not respond to treatment, sputum culture should be considered, and culture for Mycobacterium tuberculosis should be carried out in persons with a chronic productive cou

    In people managed in the community, determining the causative agent is not cost-effective and typically does not alter management.[22] For people who do not respond to treatment, sputum culture should be considered, and culture for Mycobacterium tuberculosis should be carried out in persons with a chronic productive cough.[61] Microbiological evaluation is also indicated in severe pneumonia, alcoholism, asplenia, immunosuppression, HIV infection, and those being empirically treated for MRSA of pseudomonas.[34][70] Although positive blood culture and pleural fluid culture definitively establish the diagnosis of the type of micro-organism involved, a positive sputum culture has to be interpreted with care for the possibility of colonisation of respiratory tract.[34] Testing for other specific organisms may be recommended during outbreaks, for public health reasons.[61] In those hospitalized for severe disease, both sputum and blood cultures are recommended,[61] as well as testing the urine for antigens to Legionella and Streptococcus.[71] Viral infections, can be confirmed via detection of either the virus or its antigens with culture or polymerase chain reaction (PCR), among other techniques.[12] Mycoplasma, Legionella, Streptococcus, and Chlamydia can also be detected using PCR techniques on bronchoalveolar lavage and nasopharyngeal swab.[34] The causative agent is determined in only 15% of cases with routine microbiological tests.[9]

    Classification

    Pneumonitis refers to lung inflammation; pneumonia refers to pneumonitis, usually due to infection but sometimes non-infectious, that has the additional feature of pulmonary consolidation.[72] Pneumonia is most commonly classified by where or how it was acquired: community-acquired, aspiration, healthcare-associated, hospital-acquired, and ventilator-associated pneumonia.[35] It may also be classified by the area of the lung affected: lobar pneumonia, bronchial pneumonia and acute interstitial pneumonia;[35] or by the causative organism.[73] Pneumonia in children may additionally be classified based on signs and symptoms as non-severe, severe, or very severe.[74]

    The setting in which pneumonia develops is important to treatment,[75][76]The setting in which pneumonia develops is important to treatment,[75][76] as it correlates to which pathogens are likely suspects,[75] which mechanisms are likely, which antibiotics are likely to work or fail,[75] and which complications can be expected based on the person's health status.

    Community-acquired pneumonia (CAP) is acquired in the community,[75][76] outside of health care facilities. Compared with health care–associated pneumonia, it is less likely to involve multidrug-resistant bacteria. Although the latter are no longer rare in CAP,[75] they are still less likely.

    Healthcare

    Health care–associated pneumonia (HCAP) is an infection associated with recent exposure to the health care system,health care system,[75] including hospitals, outpatient clinics, nursing homes, dialysis centers, chemotherapy treatment, or home care.[76] HCAP is sometimes called MCAP (medical care–associated pneumonia).

    People may become infected with pneumonia in a hospital; this is de

    People may become infected with pneumonia in a hospital; this is defined as pneumonia not present at the time of admission (symptoms must start at least 48 hours after admission).[76][75] It is likely to involve hospital-acquired infections, with higher risk of multidrug-resistant pathogens. People in a hospital often have other medical conditions, which may make them more susceptible to pathogens in the hospital.

    Ventilator-associated pneumonia occurs in people breathing with the help of mechanical ventilation.[75][32] Ventilator-associated pneumonia is specifically defined as pneumonia that arises more than 48 to 72 hours after endotracheal intubation.[76]

    Several diseases can present with similar signs and symptoms to pneumonia, such as: chronic obstructive pulmonary disease, asthma, pulmonary edema, bronchiectasis, lung cancer, and pulmonary emboli.[9] Unlike pneumonia, asthma and COPD typically present with wheezing, pulmonary edema presents with an abnormal electrocardiogram, cancer and bronchiectasis present with a cough of longer duration, and pulmonary emboli present with acute onset sharp chest pain and shortness of breath.[9] Mild pneumonia should be differentiated from upper respiratory tract infection (URTI). Severe pneumonia should be differentiated from acute heart failure. Pulmonary infiltrates that resolved after giving mechanical ventilation should point to heart failure and atelectasis rather than pneumonia. For recurrent pneumonia, underlying lung cancer, metastasis, tuberculosis, a foreign bodies, immunosuppression, and hypersensitivity should be suspected.[34]

    Prevention

    Prevention includes <

    Prevention includes vaccination, environmental measures and appropriate treatment of other health problems.[22] It is believed that, if appropriate preventive measures were instituted globally, mortality among children could be reduced by 400,000; and, if proper treatment were universally available, childhood deaths could be decreased by another 600,000.[24]

    VaccinationVaccination prevents against certain bacterial and viral pneumonias both in children and adults. Influenza vaccines are modestly effective at preventing symptoms of influenza,[12][77] The Center for Disease Control and Prevention (CDC) recommends yearly influenza vaccination for every person 6 months and older.[78] Immunizing health care workers decreases the risk of viral pneumonia among their patients.[71]

    Vaccinations against Vaccinations against Haemophilus influenzae and Streptococcus pneumoniae have good evidence to support their use.[48] There is strong evidence for vaccinating children under the age of 2 against Streptococcus pneumoniae (pneumococcal conjugate vaccine).[79][80][81] Vaccinating children against Streptococcus pneumoniae has led to a decreased rate of these infections in adults, because many adults acquire infections from children. A Streptococcus pneumoniae vaccine is available for adults, and has been found to decrease the risk of invasive pneumococcal disease by 74%, but there is insufficient evidence to suggest using the pneumococcal vaccine to prevent pneumonia or death in the general adult population.[82] The CDC recommends that young children and adults over the age of 65 receive the pneumococcal vaccine, as well as older children or younger adults who have an increased risk of getting pneumococcal disease.[81] The pneumococcal vaccine has been shown to reduce the risk of community acquired pneumonia in people with chronic obstructive pulmonary disease, but does not reduce mortality or the risk of hospitalization for people with this condition.[83] People with COPD are recommended by a number of guidelines to have a pneumococcal vaccination.[83] Other vaccines for which there is support for a protective effect against pneumonia include pertussis, varicella, and measles.[84]

    When influenza outbreaks occur, medications such as amantadine or rimantadine may help prevent the condition, but they are associated with side effects.[85] Zanamivir or oseltamivir decrease the chance that people who are exposed to the virus will develop symptoms; however, it is recommended that potential side effects are taken into account.[86]

    Other

    Smoking cessation[61] and reducing indoor air pollution, such as that from cooking indoors with wood, crop residues or dung, are both recommended.[22][24] Smoking appears to be the single biggest risk factor for pneumococcal pneumonia in otherwise-healthy adults.[71] Hand hygiene and coughing into one's sleeve may also be effective preventative measures.[84] Wearing surgical masks by the sick may also prevent illness.[71]

    Appropriately treating underlying illnesses (such as Appropriately treating underlying illnesses (such as HIV/AIDS, diabetes mellitus, and malnutrition) can decrease the risk of pneumonia.[24][84][87] In children less than 6 months of age, exclusive breast feeding reduces both the risk and severity of disease.[24] In people with HIV/AIDS and a CD4 count of less than 200 cells/uL the antibiotic trimethoprim/sulfamethoxazole decreases the risk of Pneumocystis pneumonia[88] and is also useful for prevention in those that are immunocompromised but do not have HIV.[89]

    Testing pregnant women for Group B Streptococcus and Chlamydia trachomatis, and administering antibiotic treatment, if needed, reduces rates of pneumonia in infants;[90][91] preventive measures for HIV transmission from mother to child may also be efficient.[92] Suctioning the mouth and throat of infants with meconium-stained amniotic fluid has not been found to reduce the rate of aspiration pneumonia and may cause potential harm,[93] thus this practice is not recommended in the majority of situations.[93] In the frail elderly good oral health care may lower the risk of aspiration pneumonia.[94] Zinc supplementation in children 2 months to five years old appears to reduce rates of pneumonia.[95]

    For people with low levels of vitamin C in their diet or blood, taking vitamin C supplements may be suggested to decrease the risk of pneumonia, although there is no strong evidence of benefit.[96] There is insufficient evidence to recommend that the general population take vitamin C to prevent pneumonia.[97]

    For adults and children in the hospital who require a respirator, there is no strong evidence indicating a difference between heat and moisture exchangers and heated humidifiers for preventing pneumonia.[98] There is no good evidence that one approach to mouth care is better than others in preventing nursing home acquired pneumonia.[99] There is tentative evidence that laying flat on the back compared to semi-raised increases pneumonia risks in people who are intubated.[100]

    Antibiotics by mouth, rest, simple analgesics, and fluids usually suffice for complete resolution.[61] However, those with other medical conditions, the elderly, or those with significant trouble breathing may require more advanced care. If the symptoms worsen, the pneumonia does not improve with home treatment, or complications occur, hospitalization may be required.[61] Worldwide, approximately 7–13% of cases in children result in hospitalization,[22] whereas in the developed world between 22 and 42% of adults with community-acquired pneumonia are admitted.[61] The CURB-65 score is useful for determining the need for admission in adults.[61] If the score is 0 or 1, people can typically be managed at home; if it is 2, a short hospital stay or close follow-up is needed; if it is 3–5, hospitalization is recommended.[61] In children those with respiratory distress or oxygen saturations of less than 90% should be hospitalized.[101] The utility of chest physiotherapy in pneumonia has not yet been determined.[102][103] Over-the-counter cough medicine has not been found to be effective,[104] nor has the use of zinc in children.[105] There is insufficient evidence for mucolytics.[104] There is no strong evidence to recommend that children who have non-measles related pneumonia take vitamin A supplements.[106] Vitamin D, as of 2018 is of unclear benefit in children.[107]

    Pneumonia can cause severe illness in a number of ways, and pneumonia with evidence of organ dysfunction may require intensive care unit admission for observation and specific treatment.[108] The main impact is on the respiratory and the circulatory system. Respiratory failure not responding to normal oxygen therapy may require heated humidified high-flow therapy delivered through nasal cannulae,intensive care unit admission for observation and specific treatment.[108] The main impact is on the respiratory and the circulatory system. Respiratory failure not responding to normal oxygen therapy may require heated humidified high-flow therapy delivered through nasal cannulae,[108] non-invasive ventilation,[109] or in severe cases invasive ventilation through an endotracheal tube.[108] Regarding circulatory problems as part of sepsis, evidence of poor blood flow or low blood pressure is initially treated with 30 ml/kg of crystalloid infused intravenously.[34] In situations where fluids alone are ineffective, vasopressor medication may be required.[108]

    For adults with moderate or severe acute respiratory distress syndrome (ARDS) undergoing mechanical ventilation, there is a reduction in mortality when people lay on their front for at least 12 hours a day. However, this increases the risk of endotracheal tube obstruction and pressure sores.[110]

    Antibiotics improve outcomes in those with bacterial pneumonia.[13] The first dose of antibiotics should be given as soon as possible.[34] Increased use of antibiotics, however, may lead to the development of antimicrobial resistant strains of bacteria.[111] Antibiotic choice depends initially on the characteristics of the person affected, such as age, underlying health, and the location the infection was acquired. Antibiotic use is also associated with side effects such as nausea, diarrhea, dizziness, taste distortion, or headaches.[111] In the UK, treatment before culture results with amoxicillin is recommended as the first line for community-acquired pneumonia, with doxycycline or clarithromycin as alternatives.[61] In North America, amoxicillin, doxycycline, and in some areas a macrolides (such as azithromycin or erythromycin) is the first-line outpatient treatment in adults.[36][112][70] In children with mild or moderate symptoms, amoxicillin taken by mouth is the first line.[101][113][114] The use of fluoroquinolones in uncomplicated cases is discouraged due to concerns about side-effects and generating resistance in light of there being no greater benefit.[36][115]

    For those who require hospitalization and caught their pneumonia in

    For those who require hospitalization and caught their pneumonia in the community the use of a β-lactam such as cephazolin plus macrolide such as azithromycin is recommended.[116][70] A fluoroquinolone may replace azithromycin but is less preferred.[70] Antibiotics by mouth and by injection appear to be similarly effective in children with severe pneumonia.[117]

    The duration of treatment has traditionally been seven to ten days, but increasing evidence suggests that shorter courses (3–5 days) may be effective for certain types of pneumonia and may reduce the risk of antibiotic resistance.[118][119][120][121] For pneumonia that is associated with a ventilator caused by non-fermenting Gram-negative bacilli (NF-GNB), a shorter course of antibiotics increases the risk that the pneumonia will return.[120] Recommendations for hospital-acquired pneumonia include third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and vancomycin.[76] These antibiotics are often given intravenously and used in combination.[76] In those treated in hospital, more than 90% improve with the initial antibiotics.[27] For people with ventilator-acquired pneumonia, the choice of antibiotic therapy will depend on the person's risk of being infected with a strain of bacteria that is multi-drug resistant.[32] Once clinically stable, intravenous antibiotics should be switched to oral antibiotics.[34] For those with Methicillin resistant Staphylococcus aureus (MRSA) or Legionella infections, prolonged antibiotics may be beneficial.[34]

    The addition of corticosteroids to standard antibiotic treatment appears to improve outcomes, reducing death and morbidity for adults with severe community acquired pneumonia, and reducing death for adults and children with non-severe community acquired pneumonia.[122][123] A 2017 review therefore recommended them in adults with severe community acquired pneumonia.[122] A 2019 guideline however recommended against there general use, unless refractory shock was present.[70] Side effects associated with the use of corticosteroids include high blood sugar.[122] There is some evidence that adding corticosteroids to the standard PCP pneumonia treatment may be beneficial for people who are infected with HIV.[42]

    The use of granulocyte colony stimulating factor (G-CSF) along with antibiotics does not appear to reduce mortality and routine use for treating pneumonia is not supported by evidence.[124]

    Neuraminidase inhibitors may be used to treat viral pneumonia caused by influenza viruses (influenza A and influenza B).[12] No specific antiviral medications are recommended for other types of community acquired viral pneumonias including SARS coronavirus, adenovirus, hantavirus, and parainfluenza virus.[12] Influenza A may be treated with rimantadine or amantadine, while influenza A or B may be treated with oseltamivir, zanamivir or peramivir.[12] These are of most benefit if they are started within 48 hours of the onset of symptoms.[12] Many strains of H5N1 influenza A, also known as avian influenza or "bird flu", have shown resistance to rimantadine and amantadine.[12] The use of antibiotics in viral pneumonia is recommended by some experts, as it is impossible to rule out a complicating bacterial infection.[12] The British Thoracic Society recommends that antibiotics be withheld in those with mild disease.[12] The use of corticosteroids is controversial.[12]

    AspirationIn general, aspiration pneumonitis is treated conservatively with antibiotics indicated only for aspiration pneumonia.[125] The choice of antibiotic will depend on several factors, including the suspected causative organism and whether pneumonia was acquired in the community or developed in a hospital setting. Common options include clindamycin, a combination of a beta-lactam antibiotic and metronidazole, or an aminoglycoside.[126] Corticosteroids are sometimes used in aspiration pneumonia, but there is limited evidence to support their effectiveness.[125]

    Follow-up

    The British Thoracic Society recommends that a follow-up chest radiograph be taken in people with persistent symptoms, smokers, and people older than 50.[61] American guidelines vary, from generally recommending a follow-up chest radiograph[127] to not mentioning any follow-up.[71]

    Prognosis

    With treatment, most types of bacterial pneumonia will stabilize in 3–6 days.[2] It often takes a few weeks before most symptoms resolve.[2] X-ray findings typically clear within four weeks and mortality is low (less than 1%).[23][128] In the elderly or people with other lung problems, recovery may take more than 12 weeks. In persons requiring hospitalization, mortality may be as high as 10%, and in those requiring intensive care it may reach 30–50%.[23] Pneumonia is the most common hospital-acquired infection that causes death.[27] Before the advent of antibiotics, mortality was typically 30% in those that were hospitalized.[20] However, for those whose lung condition deteriorates within 72 hours, the problem is usually due to sepsis.[34] If pneumonia deteriorates after 72 hours, it could be due to nosocomial infection or excerbation of other underlying comorbidities.[34] About 10% of those discharged from hospital are readmitted due to underlying co-morbidities such as heart, lung, or neurological disorders, or due to new onset of pneumonia.[34]

    Complications may occur in particular in the elderly and those wi

    Complications may occur in particular in the elderly and those with underlying health problems.[128] This may include, among others: empyema, lung abscess, bronchiolitis obliterans, acute respiratory distress syndrome, sepsis, and worsening of underlying health problems.[128]

    Clinical prediction rules have been developed to more objectively predict outcomes of pneumonia.[27] These rules are often used to decide whether to hospitalize the person.[27]

    • Pneumonia severit

      In pneumonia, a collection of fluid may form in the space that surrounds the lung.[130] Occasionally, microorganisms will infect this fluid, causing an empyema.[130] To distinguish an empyema from the more common simple parapneumonic effusion, the fluid may be collected with a needle (thoracentesis), and examined.[130] If this shows evidence of empyema, complete drainage of the fluid is necessary, often requiring a drainage catheter.[130] In severe cases of empyema, surgery may be needed.[130] If the infected fluid is not drained, the infection may persist, because antibiotics do not penetrate well into the pleural cavity. If the fluid is sterile, it must be drained only if it is causing symptoms or remains unresolved.[130]

      In rare circumstances, bacteria in the lung will form a pocket of infected fluid called a lung abscess.[130] Lung abscesses can usually be seen with a chest X-ray but frequently require a chest CT scan to confirm the diagnosis.[130] Abscesses typically occur in aspiration pneumonia, and often contain several types of bacteria. Long-term antibiotics are usually adequate to treat a lung abscess, but sometimes the abscess must be drained by a surgeon or radiologist.[130]

      Respiratory and circulatory failure

      Pneumonia can cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response. The lungs quickly fill with fluid and become stiff. This stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid, may require long periods of mechanical ventilation for survival.[37] Other causes of circulatory failure are hypoxemia

      In rare circumstances, bacteria in the lung will form a pocket of infected fluid called a lung abscess.[130] Lung abscesses can usually be seen with a chest X-ray but frequently require a chest CT scan to confirm the diagnosis.[130] Abscesses typically occur in aspiration pneumonia, and often contain several types of bacteria. Long-term antibiotics are usually adequate to treat a lung abscess, but sometimes the abscess must be drained by a surgeon or radiologist.[130]

      Pneumonia can cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response. The lungs quickly fill with fluid and become stiff. This stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid, may require long periods of mechanical ventilation for survival.[37] Other causes of circulatory failure are hypoxemia, inflammation, and increased coagulability.[34]

      Sepsis is a potential complication of pneumonia but usually occurs in peopl

      Sepsis is a potential complication of pneumonia but usually occurs in people with poor immunity or hyposplenism. The organisms most commonly involved are Streptococcus pneumoniae, Haemophilus influenzae, and Klebsiella pneumoniae. Other causes of the symptoms should be considered such as a myocardial infarction or a pulmonary embolism.[131]

      Pneumonia is a common illness affecting approximately 450 million people a year and occurring in all parts of the world.[12] It is a major cause of death among all age groups resulting in 4 million deaths (7% of the world's total death) yearly.[12][13] Rates are greatest in children less than five, and adults older than 75 years.[12] It occurs about five times more frequently in the developing world than in the developed world.[12] Viral pneumonia accounts for about 200 million cases.[12] In the United States, as of 2009, pneumonia is the 8th leading cause of death.[23]

      Children

      In 2008, pneumonia occurred in approximately 156 million children (151 million in the developing world and 5 million in the developed world).[12] In 2010, it resulted in 1.3 million deaths, or 18% of all deaths in those under five years, of which 95% occurred in the developing world.[12][22][133] Countries with the greatest burden of disease include India (43 million), China (21 million) and Pakistan (10 million).[134] It is the leading cause of death among children in low income countries.[12][13] Many of these deaths occur in the newborn period. The World Health Organization estimates that one in three newborn infant deaths is due to pneumonia.[135] Approximately half of these deaths can be prevented, as they are caused by the bacteria for which an effective vaccine is available.[136] In 2011, pneumonia was the most common reason for admission to the hospital after an emergency department visit in the U.S. for infants and children.[137]

      History

      A poster with a shark in the middle of it, which reads "Pneumonia Strikes Like a Man Eating Shark Led by its Pilot Fish the Common Cold"
      WPA poster, 1936/1937

      Pneumonia has been a common disease throughout human history.[138] The word is from Greek πνεύμων (pneúmōn) meaning "lung".[139] The symptoms were described by Hippocrates (c. 460–370 BC):[138] "Peripneumonia, and pleuritic affections, are to be thus observed: If the fever be acute, and if there be pains on either side, or in both, and if expiration be if cough be present, and the sputa expectorated be of a blond or livid color, or likewise thin, frothy, and florid, or having any other character different from the common... When pneumonia is at its height, the case is beyond remedy if he is not purged, and it is bad if he has dyspnoea, and urine that is thin and acrid, and if sweats come out about the neck and head, for such sweats are bad, as proceeding from the suffocation, rales, and the violence of the disease which is obtaining the upper hand."[140] However, Hippocrates referred to pneumonia as a disease "named by the ancients". He also reported the results of surgical drainage of empyemas. Maimonides (1135–1204 AD) observed: "The basic symptoms that occur in pneumonia and that are never lacking are as follows: acute fever, sticking pleuritic pain in the side, short rapid breaths, serrated pulse and cough."[141] This clinical description is quite similar to those found in modern textbooks, and it reflected the extent of medical knowledge through the Middle Ages into the 19th century.

      Edwin Klebs was the first to observe bacteria in the airways of persons having died of pneumonia in 1875.[142] Initial work identifying the two common bacterial causes, Streptococcus pneumoniae and Klebsiella pneumoniae, was performed by Carl Friedländer[143] and Albert Fraenkel[144] in 1882 and 1884, respectively. Friedländer's initial work introduced the Gram stain, a fundamental laboratory test still used today to identify and categorize bacteria. Christian Gram's paper describing the procedure in 1884 helped to differentiate the two bacteria, and showed that pneumonia could be caused by more than one microorganism.[145]

      Sir William Osler, known as "the father of modern medicine", appreciated the death and disability caused by pneumonia, describing it as the "captain of the men of death" in 1918, as it had overtaken tuberculosis as one of the leading causes of death in this time. This phrase was originally coined by John Bunyan in reference to "consumption" (tuberculosis).[146][147] Osler also described pneumonia as "the old man's friend" as death was often quick and painless when there were much slower and more painful ways to die.[20]

      Viral pneumonia was first described by Hobart Reimann in 1938. Reimann, Chairman of the Department of Medicine at Jefferson Medical College, had established the practice of routinely typing the pneumoccocal organism in cases where pneumonia presented. Out of this work, the distinction between viral and bacterial strains was noticed.[148]

      Several developments in the 1900s improved the outcome for those with pneumonia. With the advent of penicillin and other antibiotics, modern surgical techniques, and intensive care in the 20th century, mortality from pneumonia, which had approached 30%, dropped precipitously in the developed world. Vaccination of infants against Haemophilus influenzae type B began in 1988 and led to a dramatic decline in cases shortly thereafter.[149] Vaccination against Streptococcus pneumoniae in adults began in 1977, and in children in 2000, resulting in a similar decline.[150]

      Society and culture

      AwarenessIn 2008, pneumonia occurred in approximately 156 million children (151 million in the developing world and 5 million in the developed world).[12] In 2010, it resulted in 1.3 million deaths, or 18% of all deaths in those under five years, of which 95% occurred in the developing world.[12][22][133] Countries with the greatest burden of disease include India (43 million), China (21 million) and Pakistan (10 million).[134] It is the leading cause of death among children in low income countries.[12][13] Many of these deaths occur in the newborn period. The World Health Organization estimates that one in three newborn infant deaths is due to pneumonia.[135] Approximately half of these deaths can be prevented, as they are caused by the bacteria for which an effective vaccine is available.[136] In 2011, pneumonia was the most common reason for admission to the hospital after an emergency department visit in the U.S. for infants and children.[137]

      History

      Pneumonia has been a common disease throughout human history.[138] The word is from Greek πνεύμων (pneúmōn) meaning "lung".[139] The symptoms were described by Hippocrates (c. 460–370 BC):[138] "Peripneumonia, and pleuritic affections, are to be thus observed: If the fever be acute, and if there be pains on either side, or in both, and if expiration be if cough be present, and the sputa expectorated be of a blond or livid color, or likewise thin, frothy, and florid, or having any other character different from the common... When pneumonia is at its height, the case is beyond remedy if he is not purged, and it is bad if he has dyspnoea, and urine that is thin and acrid, and if sweats come out about the neck and head, for such sweats are bad, as proceeding from the suffocation, rales, and the violence of the disease which is obtaining the upper hand."[140] However, Hippocrates referred to pneumonia as a disease "named by the ancients". He also reported the results of surgical drainage of empyemas. Maimonides (1135–1204 AD) observed: "The basic symptoms that occur in pneumonia and that are never lacking are as follows: acute fever, sticking pleuritic pain in the side, short rapid breaths, serrated pulse and cough."[141] This clinical description is quite similar to those found in modern textbooks, and it reflected the extent of medical knowledge through the Middle Ages into the 19th century.

      Edwin Klebs was the first to observe bacteria in the airways of persons having died of pneumonia in 1875.[142] Initial work identifying the two common bacterial causes, Streptococcus pneumoniae and Klebsiella pneumoniae, was performed by Carl Friedländer[143] and Albert Fraenkel[144] in 1882 and 1884, respectively. Friedländer's initial work introduced the Gram stain, a fundamental laboratory test still used today to identify an

      Edwin Klebs was the first to observe bacteria in the airways of persons having died of pneumonia in 1875.[142] Initial work identifying the two common bacterial causes, Streptococcus pneumoniae and Klebsiella pneumoniae, was performed by Carl Friedländer[143] and Albert Fraenkel[144] in 1882 and 1884, respectively. Friedländer's initial work introduced the Gram stain, a fundamental laboratory test still used today to identify and categorize bacteria. Christian Gram's paper describing the procedure in 1884 helped to differentiate the two bacteria, and showed that pneumonia could be caused by more than one microorganism.[145]

      Sir William Osler, known as "the father of modern medicine", appreciated the death and disability caused by pneumonia, describing it as the "captain of the men of death" in 1918, as it had overtaken tuberculosis as one of the leading causes of death in this time. This phrase was originally coined by John Bunyan in reference to "consumption" (tuberculosis).[146][147] Osler also described pneumonia as "the old man's friend" as death was often quick and painless when there were much slower and more painful ways to die.[20]

      Viral pneumonia was first described by Hobart Reimann in 1938. Reimann, Chairman of the Department of Medicine at Jefferson Medical College, had established the practice of routinely typing the pneumoccocal organism in cases where pneumonia presented. Out of this work, the distinction between viral and bacterial strains was noticed.[148]

      Several developments in the 1900s improved the outcome for those with pneumonia. With the advent of penicillin and other antibiotics, modern surgical techniques, and intensive care in the 20th century, mortality from pneumonia, which had approached 30%, dropped precipitously in the developed world. Vaccination of infants against Haemophilus influenzae type B began in 1988 and led to a dramatic decline in cases shortly thereafter.[149] Vaccination against Streptococcus pneumoniae in adults began in 1977, and in children in 2000, resulting in a similar decline.[150]

      Due to the relatively low awareness of the disease, 12 November was declared as the annual World Pneumonia Day, a day for concerned citizens and policy makers to take action against the disease, in 2009.[151][152]

      Costs

      The global economic cost of community-acquired pneumonia has been estimated at $17 billion annually.[23] Other estimates are considerably higher. In 2012 the estimated aggregate costs of treating pne

      The global economic cost of community-acquired pneumonia has been estimated at $17 billion annually.[23] Other estimates are considerably higher. In 2012 the estimated aggregate costs of treating pneumonia in the United States were $20 billion;[153] the median cost of a single pneumonia-related hospitalization is over $15,000.[154] According to data released by the Centers for Medicare and Medicaid Services, average 2012 hospital charges for inpatient treatment of uncomplicated pneumonia in the U.S. were $24,549 and ranged as high as $124,000. The average cost of an emergency room consult for pneumonia was $943 and the average cost for medication was $66.[155] Aggregate annual costs of treating pneumonia in Europe have been estimated at €10 billion.[156]

      ReferencesFootnotes

      Citations

      1. ^ a b c Ashby B, Turkington C (2007). The encyclopedia of infectious diseases (3rd ed.). New York: Facts on File. p. 242. ISBN 978-0-8160-6397-0. Retrieved 21 April 2011.