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===Early classification schemes=== | ===Early classification schemes=== | ||
Pneumonias can be classified in several ways. Pathologists originally classified them according to the [[anatomy|anatomic]] changes that were found in the lungs during [[autopsy|autopsies]]. As more became known about the microorganisms causing pneumonia, a [[microbiology|microbiologic]] classification arose, and with the advent of [[x-ray]]s, a [[radiology|radiological]] classification. Another important system of classification is the combined clinical classification, which combines factors such as age, risk factors for certain microorganisms, the presence of underlying lung disease and underlying systemic disease, and whether the person has recently been hospitalized. | |||
Initial descriptions of pneumonia focused on the anatomic or [[pathology|pathologic]] appearance of the lung, either by direct inspection at [[autopsy]] or by its appearance under a [[microscope]]. 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]]''. ''Multilobar'' pneumonia involves more than one lobe, and it often causes a more severe illness.''Interstitial'' pneumonia involves the areas in between the alveoli, and it may be called "interstitial pneumonitis." It is more likely to be caused by viruses or by atypical bacteria. | Initial descriptions of pneumonia focused on the anatomic or [[pathology|pathologic]] appearance of the lung, either by direct inspection at [[autopsy]] or by its appearance under a [[microscope]]. 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]]''. ''Multilobar'' pneumonia involves more than one lobe, and it often causes a more severe illness.''Interstitial'' pneumonia involves the areas in between the alveoli, and it may be called "interstitial pneumonitis." It is more likely to be caused by viruses or by atypical bacteria. | ||
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Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753; Philip Marcus, M.D., M.P.H.[2]
Historical Perspective
The symptoms of pneumonia were described by Hippocrates (c. 460 BC–380 BC):
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.
However, Hippocrates himself referred to pneumonia as a disease "named by the ancients." He also reported the results of surgical drainage of empyemas. Maimonides (1138–1204 AD) observed "The basic symptoms which occur in pneumonia and which are never lacking are as follows: acute fever, sticking [pleuritic] pain in the side, short rapid breaths, serrated pulse and cough."[1] 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.
Bacteria were first seen in the airways of individuals who died from pneumonia by Edwin Klebs in 1875.[2] Initial work identifying the two common bacterial causes Streptococcus pneumoniae and Klebsiella pneumoniae was performed by Carl Friedländer[3] and Albert Fränkel (1848-1916)[4] in 1882 and 1884, respectively. Friedländer's initial work introduced the Gram stain, a fundamental laboratory test still used to identify and categorize bacteria. Christian Gram's paper describing the procedure in 1884 helped differentiate the two different bacteria and showed that pneumonia could be caused by more than one microorganism.[5]
Sir William Osler, known as "the father of modern medicine," appreciated the morbidity and mortality of pneumonia, describing it as the "captain of the men of death" in 1918. However, several key 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 twentieth century, mortality from pneumonia 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.[6] Vaccination against Streptococcus pneumoniae in adults began in 1977 and in children began in 2000, resulting in a similar decline.[7]
Early classification schemes
Pneumonias can be classified in several ways. Pathologists originally classified them according to the anatomic changes that were found in the lungs during autopsies. As more became known about the microorganisms causing pneumonia, a microbiologic classification arose, and with the advent of x-rays, a radiological classification. Another important system of classification is the combined clinical classification, which combines factors such as age, risk factors for certain microorganisms, the presence of underlying lung disease and underlying systemic disease, and whether the person has recently been hospitalized.
Initial descriptions of pneumonia focused on the anatomic or pathologic appearance of the lung, either by direct inspection at autopsy or by its appearance under a microscope. 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. Multilobar pneumonia involves more than one lobe, and it often causes a more severe illness.Interstitial pneumonia involves the areas in between the alveoli, and it may be called "interstitial pneumonitis." It is more likely to be caused by viruses or by atypical bacteria.
The discovery of x-rays made it possible to determine the anatomic type of pneumonia without direct examination of the lungs at autopsy and led to the development of a radiological classification. 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 with x-rays alone.
With the advent of modern microbiology, classification based upon the causative microorganism became possible. 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.
References
- ↑ Maimonides, Fusul Musa ("Pirkei Moshe").
- ↑ Klebs E. Beiträge zur Kenntniss der pathogenen Schistomyceten. VII Die Monadinen. Arch. exptl. Pathol. Parmakol. 1875 Dec 10;4(5/6):40–488.
- ↑ Friedländer C. Über die Schizomyceten bei der acuten fibrösen Pneumonie. Virchow's Arch pathol. Anat. u. Physiol. 1882 Feb 4;87(2):319–324.
- ↑ Fraenkel A. Über die genuine Pneumonie, Verhandlungen des Congress für innere Medicin. Dritter Congress. 1884 April 21;3:17–31.
- ↑ Gram C. Über die isolierte Färbung der Schizomyceten in Schnitt- und Trocken-präparaten. Fortschr. Med. 1884 March 15;2(6):185–189.
- ↑ Adams WG, Deaver KA, Cochi SL, et al. Decline of childhood Haemophilus influenzae type b (Hib) disease in the Hib vaccine era.JAMA1993;269:221-6. PMID 8417239
- ↑ Whitney CG, Farley MM, Hadler J, et al. Decline in invasive pneumococcal disease after the introduction of pneumococcal protein-polysaccharide conjugate vaccine. New Engl J Med. 2003;348:1737–1746. PMID 12724479