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{{Pneumonia}}
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==Overview==
==Overview==
Several pneumonia classification schemes have been described. The earliest classification was based on the anatomical distribution of the infectious process observed on [[autopsy]] and eventually on [[medical imaging]]. Advances in [[microbiology]] led to a classification based on etiologic group ([[Bacteria|bacterial]], [[Virus|viral]], [[Fungus|fungal]]) despite difficulties often encountered in identifying the etiologic agent. With the advent of [[Antibiotic|antibiotics]] and the rise in resistance, a classification scheme taking into account the setting in which the pneumonia was acquired was introduced to guide empiric therapy. Pneumonia was classified into [[community-acquired pneumonia]] (CAP), healthcare-associated pneumonia (HCAP), [[ventilator-associated pneumonia]] (VAP), and [[hospital-acquired pneumonia]] (HAP). Despite significant overlap, this classification is essential in selecting appropriate [[antimicrobial]] therapy.


==Classification==
==Classification==
Pneumonia can be classified according to the source of infection, either in the community or in a healthcare setting. The following are the 4 categories described by the Infectious Diseases Society of America and American Thoracic Society:<ref name="MandellWunderink2007">{{cite journal|last1=Mandell|first1=L. A.|last2=Wunderink|first2=R. G.|last3=Anzueto|first3=A.|last4=Bartlett|first4=J. G.|last5=Campbell|first5=G. D.|last6=Dean|first6=N. C.|last7=Dowell|first7=S. F.|last8=File|first8=T. M.|last9=Musher|first9=D. M.|last10=Niederman|first10=M. S.|last11=Torres|first11=A.|last12=Whitney|first12=C. G.|title=Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults|journal=Clinical Infectious Diseases|volume=44|issue=Supplement 2|year=2007|pages=S27–S72|issn=1058-4838|doi=10.1086/511159}}</ref><ref>{{cite journal|title=Guidelines for the Management of Adults with Hospital-acquired, Ventilator-associated, and Healthcare-associated Pneumonia|journal=American Journal of Respiratory and Critical Care Medicine|volume=171|issue=4|year=2005|pages=388–416|issn=1073-449X|doi=10.1164/rccm.200405-644ST}}</ref>
===Classification by Setting===
Despite having several classification schemes, the most clinically relevant classification relates to the setting in which pneumonia was acquired. The following 5 categories are defined by the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS):<ref name="MandellWunderink2007">{{cite journal|last1=Mandell|first1=L. A.|last2=Wunderink|first2=R. G.|last3=Anzueto|first3=A.|last4=Bartlett|first4=J. G.|last5=Campbell|first5=G. D.|last6=Dean|first6=N. C.|last7=Dowell|first7=S. F.|last8=File|first8=T. M.|last9=Musher|first9=D. M.|last10=Niederman|first10=M. S.|last11=Torres|first11=A.|last12=Whitney|first12=C. G.|title=Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults|journal=Clinical Infectious Diseases|volume=44|issue=Supplement 2|year=2007|pages=S27–S72|iss#=1058-4838|doi=10.1086/511159}}</ref><ref>{{cite journal|title=Guidelines for the Management of Adults with Hospital-acquired, Ventilator-associated, and Healthcare-associated Pneumonia|journal=American Journal of Respiratory and Critical Care Medicine|volume=171|issue=4|year=2005|pages=388–416|issn=1073-449X|doi=10.1164/rccm.200405-644ST}}</ref>


*[[Community-acquired pneumonia]] (CAP)
# '''Community-acquired pneumonia (CAP)''': Pneumonia not acquired in a hospital setting or in a long-term care facility.<ref name="pmid12682561">{{cite journal| author=Andrews J, Nadjm B, Gant V, Shetty N| title=Community-acquired pneumonia. | journal=Curr Opin Pulm Med | year= 2003 | volume= 9 | issue= 3 | pages= 175-80 | pmid=12682561 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12682561  }} </ref>
# '''Hospital-acquired pneumonia (HAP)''': Pneumonia that occurs after 48 hours (or more) of hospitalization that was absent on admission.
# '''Healthcare-associated pneumonia (HCAP)''':  Pneumonia in patients hospitalized within 90 days of infection, residents of long-term care facility, patients receiving parenteral antibiotics and  chemotherapy within 30 days of infection.
# '''Ventilator-associated pneumonia (VAP)''': Pneumonia that occurs after 48 hours (or more) of endotracheal intubation.<ref name="pmid15699079">{{cite journal| author=American Thoracic Society. Infectious Diseases Society of America| title=Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. | journal=Am J Respir Crit Care Med | year= 2005 | volume= 171 | issue= 4 | pages= 388-416 | pmid=15699079 | doi=10.1164/rccm.200405-644ST | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15699079  }} </ref>
# '''Aspiration pneumonia''': Pneumonia occuring after inhalation of colonized oropharyngeal material.<ref name="pmid11228282">{{cite journal| author=Marik PE| title=Aspiration pneumonitis and aspiration pneumonia. | journal=N Engl J Med | year= 2001 | volume= 344 | issue= 9 | pages= 665-71 | pmid=11228282 | doi=10.1056/NEJM200103013440908 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11228282  }} </ref>


*Healthcare-associated pneumonia (HCAP)
===Classification by Microbiological Agent===
Another important clinical and [[Medical laboratory|laboratory]] classification of pneumonia is based on the identification of the causative agent. Although it is of major importance for tailoring therapy, approximately one half of pneumonia do not have an identifiable causative [[organism]]. This is the main rationale behind using [[empirical]] therapy. The main groups of by causative agent are:
#[[Bacteria|Bacterial]] pneumonia
#[[Viral]] pneumonia
#[[Fungus|Fungal]] pneumonia
#[[Protozoa|Protozoal]] pneumonia
#Idiopathic interstitial pneumonia (non-infectious)
===Classification by Symptoms===
Pneumonia can also be classified as '''typical''' or '''atypical''' pneumonia, depending on the clinical manifestations, [[Chest X-ray|chest x-ray]] findings, and the [[pathogen]] that causes the [[infection]].
{| style="border: 0px; font-size: 85%; margin: 3px; width:600px;" align="center"
| valign="top" |
|+'''Typical and atypical pneumonias'''
! style="background: #4479BA; color:#FFF;  width: 150px;" |
! style="background: #4479BA; color:#FFF;  width: 250px;" | Typical Pneumonia
! style="background: #4479BA; color:#FFF;  width: 250px;" | Atypical Pneumonia
|-
| style="padding: 5px 5px; background: #F5F5F5;" | '''Common Pathogens'''
| style="padding: 5px 5px; background: #F5F5F5;" |
* ''[[Streptococcus pneumoniae]]''
* ''[[Haemophilus influenzae]]''
* ''[[Staphylococcus aureus]]''
* ''[[Escherichia coli]]''
* ''[[Klebsiella pneumoniae]]''
* ''[[Pseudomonas aeruginosa]]''
| style="padding: 5px 5px; background: #F5F5F5;" |
* ''[[Mycoplasma pneumoniae]]''
* ''[[Chlamydophila pneumoniae]]''
* ''[[Legionella pneumophila]]''
* ''[[Influenza]]''
* ''[[Parainfluenza]]''
* ''[[Respiratory syncytial virus|Respiratory syncytial virus (RSV)]]''
* ''[[Adenovirus]]''
|-
| style="padding: 5px 5px; background: #F5F5F5;" | '''Common Findings'''
| style="padding: 5px 5px; background: #F5F5F5;" |
*[[Fever]], [[Rigor|chills]]
*[[Cough|Productive cough]]
*[[Pleurisy|Pleuritic chest pain]]
*[[Dyspnea]]
*[[Leukocytosis]] with [[neutrophilia]]
*[[Chest X-ray]] with [[Consolidation (medicine)|consolidation]] and air bronchograms


*[[Ventilator-associated pneumonia]] (VAP)
| style="padding: 5px 5px; background: #F5F5F5;" |
*Gradual onset of [[fever]], without [[Rigor|chills]]
*Non-productive cough
*Normal [[White blood cells|WBC]] count or mild [[leukocytosis]]
*[[Myalgia]]
*[[Chest X-ray]] may be normal or show interstitial infiltrates
|}


*[[Hospital-acquired pneumonia]] (HAP)
===Classification by Anatomic Involvement===
Despite being the initial classification scheme developed based on findings on [[autopsy]], the [[Anatomy|anatomic]] classification is no longer of major clinical importance. Three major classes are observed:
#[[Pneumonia|Lobar]] pneumonia (involving only one lobe of the [[lung]]; mostly observed  with ''[[Streptococcus|Streptoccocus pneumoniae]]'' or ''[[Klebsiella pneumoniae]]'')
#Multilobar pneumonia
#[[Interstitial]] pneumonia (involves the [[Interstitial|interstitium]] rather than airways and [[Pulmonary alveolus|alveoli]]; mostly seen with [[Virus|viral]] and atypical pneumonia)


==Classification of Idiopathic Interstitial Pneumonias<small><small><ref name="TravisCostabel2013">{{cite journal|last1=Travis|first1=William D.|last2=Costabel|first2=Ulrich|last3=Hansell|first3=David M.|last4=King|first4=Talmadge E.|last5=Lynch|first5=David A.|last6=Nicholson|first6=Andrew G.|last7=Ryerson|first7=Christopher J.|last8=Ryu|first8=Jay H.|last9=Selman|first9=Moisés|last10=Wells|first10=Athol U.|last11=Behr|first11=Jurgen|last12=Bouros|first12=Demosthenes|last13=Brown|first13=Kevin K.|last14=Colby|first14=Thomas V.|last15=Collard|first15=Harold R.|last16=Cordeiro|first16=Carlos Robalo|last17=Cottin|first17=Vincent|last18=Crestani|first18=Bruno|last19=Drent|first19=Marjolein|last20=Dudden|first20=Rosalind F.|last21=Egan|first21=Jim|last22=Flaherty|first22=Kevin|last23=Hogaboam|first23=Cory|last24=Inoue|first24=Yoshikazu|last25=Johkoh|first25=Takeshi|last26=Kim|first26=Dong Soon|last27=Kitaichi|first27=Masanori|last28=Loyd|first28=James|last29=Martinez|first29=Fernando J.|last30=Myers|first30=Jeffrey|last31=Protzko|first31=Shandra|last32=Raghu|first32=Ganesh|last33=Richeldi|first33=Luca|last34=Sverzellati|first34=Nicola|last35=Swigris|first35=Jeffrey|last36=Valeyre|first36=Dominique|title=An Official American Thoracic Society/European Respiratory Society Statement: Update of the International Multidisciplinary Classification of the Idiopathic Interstitial Pneumonias|journal=American Journal of Respiratory and Critical Care Medicine|volume=188|issue=6|year=2013|pages=733–748|issn=1073-449X|doi=10.1164/rccm.201308-1483ST}}</ref></small></small>==
=====Major idiopathic interstitial pneumonias=====
* [[Idiopathic pulmonary fibrosis]]
* Idiopathic nonspecific [[interstitial]] pneumonia
* Respiratory bronchiolitis–[[interstitial]] lung disease
* Desquamative interstitial pneumonia
* Cryptogenic organizing pneumonia
* Acute [[interstitial]] pneumonia
=====Rare idiopathic interstitial pneumonias=====
* Idiopathic [[Lymphatic system|lymphoid]] interstitial pneumonia
* Idiopathic pleuroparenchymal fibroelastosis
==References==
==References==
{{reflist|2}}
{{reflist|2}}

Latest revision as of 21:47, 5 March 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hamid Qazi, MD, BSc [2], Alejandro Lemor, M.D. [3], Serge Korjian M.D.

Overview

Several pneumonia classification schemes have been described. The earliest classification was based on the anatomical distribution of the infectious process observed on autopsy and eventually on medical imaging. Advances in microbiology led to a classification based on etiologic group (bacterial, viral, fungal) despite difficulties often encountered in identifying the etiologic agent. With the advent of antibiotics and the rise in resistance, a classification scheme taking into account the setting in which the pneumonia was acquired was introduced to guide empiric therapy. Pneumonia was classified into community-acquired pneumonia (CAP), healthcare-associated pneumonia (HCAP), ventilator-associated pneumonia (VAP), and hospital-acquired pneumonia (HAP). Despite significant overlap, this classification is essential in selecting appropriate antimicrobial therapy.

Classification

Classification by Setting

Despite having several classification schemes, the most clinically relevant classification relates to the setting in which pneumonia was acquired. The following 5 categories are defined by the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS):[1][2]

  1. Community-acquired pneumonia (CAP): Pneumonia not acquired in a hospital setting or in a long-term care facility.[3]
  2. Hospital-acquired pneumonia (HAP): Pneumonia that occurs after 48 hours (or more) of hospitalization that was absent on admission.
  3. Healthcare-associated pneumonia (HCAP): Pneumonia in patients hospitalized within 90 days of infection, residents of long-term care facility, patients receiving parenteral antibiotics and chemotherapy within 30 days of infection.
  4. Ventilator-associated pneumonia (VAP): Pneumonia that occurs after 48 hours (or more) of endotracheal intubation.[4]
  5. Aspiration pneumonia: Pneumonia occuring after inhalation of colonized oropharyngeal material.[5]

Classification by Microbiological Agent

Another important clinical and laboratory classification of pneumonia is based on the identification of the causative agent. Although it is of major importance for tailoring therapy, approximately one half of pneumonia do not have an identifiable causative organism. This is the main rationale behind using empirical therapy. The main groups of by causative agent are:

  1. Bacterial pneumonia
  2. Viral pneumonia
  3. Fungal pneumonia
  4. Protozoal pneumonia
  5. Idiopathic interstitial pneumonia (non-infectious)

Classification by Symptoms

Pneumonia can also be classified as typical or atypical pneumonia, depending on the clinical manifestations, chest x-ray findings, and the pathogen that causes the infection.

Typical and atypical pneumonias
Typical Pneumonia Atypical Pneumonia
Common Pathogens
Common Findings

Classification by Anatomic Involvement

Despite being the initial classification scheme developed based on findings on autopsy, the anatomic classification is no longer of major clinical importance. Three major classes are observed:

  1. Lobar pneumonia (involving only one lobe of the lung; mostly observed with Streptoccocus pneumoniae or Klebsiella pneumoniae)
  2. Multilobar pneumonia
  3. Interstitial pneumonia (involves the interstitium rather than airways and alveoli; mostly seen with viral and atypical pneumonia)

Classification of Idiopathic Interstitial Pneumonias[6]

Major idiopathic interstitial pneumonias
Rare idiopathic interstitial pneumonias
  • Idiopathic lymphoid interstitial pneumonia
  • Idiopathic pleuroparenchymal fibroelastosis

References

  1. Mandell, L. A.; Wunderink, R. G.; Anzueto, A.; Bartlett, J. G.; Campbell, G. D.; Dean, N. C.; Dowell, S. F.; File, T. M.; Musher, D. M.; Niederman, M. S.; Torres, A.; Whitney, C. G. (2007). "Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults". Clinical Infectious Diseases. 44 (Supplement 2): S27–S72. doi:10.1086/511159. Unknown parameter |iss#= ignored (help)
  2. "Guidelines for the Management of Adults with Hospital-acquired, Ventilator-associated, and Healthcare-associated Pneumonia". American Journal of Respiratory and Critical Care Medicine. 171 (4): 388–416. 2005. doi:10.1164/rccm.200405-644ST. ISSN 1073-449X.
  3. Andrews J, Nadjm B, Gant V, Shetty N (2003). "Community-acquired pneumonia". Curr Opin Pulm Med. 9 (3): 175–80. PMID 12682561.
  4. American Thoracic Society. Infectious Diseases Society of America (2005). "Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia". Am J Respir Crit Care Med. 171 (4): 388–416. doi:10.1164/rccm.200405-644ST. PMID 15699079.
  5. Marik PE (2001). "Aspiration pneumonitis and aspiration pneumonia". N Engl J Med. 344 (9): 665–71. doi:10.1056/NEJM200103013440908. PMID 11228282.
  6. Travis, William D.; Costabel, Ulrich; Hansell, David M.; King, Talmadge E.; Lynch, David A.; Nicholson, Andrew G.; Ryerson, Christopher J.; Ryu, Jay H.; Selman, Moisés; Wells, Athol U.; Behr, Jurgen; Bouros, Demosthenes; Brown, Kevin K.; Colby, Thomas V.; Collard, Harold R.; Cordeiro, Carlos Robalo; Cottin, Vincent; Crestani, Bruno; Drent, Marjolein; Dudden, Rosalind F.; Egan, Jim; Flaherty, Kevin; Hogaboam, Cory; Inoue, Yoshikazu; Johkoh, Takeshi; Kim, Dong Soon; Kitaichi, Masanori; Loyd, James; Martinez, Fernando J.; Myers, Jeffrey; Protzko, Shandra; Raghu, Ganesh; Richeldi, Luca; Sverzellati, Nicola; Swigris, Jeffrey; Valeyre, Dominique (2013). "An Official American Thoracic Society/European Respiratory Society Statement: Update of the International Multidisciplinary Classification of the Idiopathic Interstitial Pneumonias". American Journal of Respiratory and Critical Care Medicine. 188 (6): 733–748. doi:10.1164/rccm.201308-1483ST. ISSN 1073-449X.