Pneumonia causes: Difference between revisions

Jump to navigation Jump to search
m (Changes made per Mahshid's request)
No edit summary
Line 1: Line 1:
__NOTOC__
__NOTOC__
{{Pneumonia}}
{{Pneumonia}}
{{CMG}}; {{AE}} [[Priyamvada Singh|Priyamvada Singh, M.D.]] [mailto:psingh13579@gmail.com]; {{AL}}; {{Ochuko}}
{{CMG}}; {{AE}}, {{HQ}}, [[Priyamvada Singh|Priyamvada Singh, M.D.]] [mailto:psingh13579@gmail.com]; {{AL}}; {{Ochuko}}


==Overview==
==Overview==
Line 136: Line 136:
|-
|-
|}
|}
===Community Acquired Pneumonia===
==Causes==
===Most Common Etiologies for Community-Acquired Pneumonia <small><ref name="pmid17278083">{{cite journal |author=Mandell LA, Wunderink RG, Anzueto A, Bartlett JG, Campbell GD, Dean NC, Dowell SF, File TM, Musher DM, Niederman MS, Torres A, Whitney CG |title=Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults |journal=[[Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America]] |volume=44 Suppl 2 |issue= |pages=S27–72 |year=2007 |month=March |pmid=17278083 |doi=10.1086/511159 |url=http://www.cid.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=17278083 |accessdate=2012-09-06}}</ref><ref name="Wong-2013">{{Cite journal  | last1 = Wong | first1 = KK. | last2 = Fistek | first2 = M. | last3 = Watkins | first3 = RR. | title = Community-acquired pneumonia caused by Yersinia enterocolitica in an immunocompetent patient. | journal = J Med Microbiol | volume = 62 | issue = Pt 4 | pages = 650-1 | month = Apr | year = 2013 | doi = 10.1099/jmm.0.053488-0 | PMID = 23242642 }}</ref><ref name="Oh-2013">{{Cite journal  | last1 = Oh | first1 = YJ. | last2 = Song | first2 = SH. | last3 = Baik | first3 = SH. | last4 = Lee | first4 = HH. | last5 = Han | first5 = IM. | last6 = Oh | first6 = DH. | title = A case of fulminant community-acquired Acinetobacter baumannii pneumonia in Korea. | journal = Korean J Intern Med | volume = 28 | issue = 4 | pages = 486-90 | month = Jul | year = 2013 | doi = 10.3904/kjim.2013.28.4.486 | PMID = 23864808 }}</ref></small>===
{| style="border: 0px; font-size: 85%; margin: 3px; width:700px;" align=center
|valign=top|
|+
! style="background: #4479BA; color:#FFF;  width: 250px;" | Outpatient
! style="background: #4479BA; color:#FFF;  width: 250px;" | Inpatient (non-ICU)
! style="background: #4479BA; color:#FFF;  width: 250px;" | Inpatient (ICU)
|-
| style="padding: 5px 5px; background: #F5F5F5;" |
#[[Streptococcus pneumoniae]]
#[[Mycoplasma pneumoniae]]
#[[Haemophilus influenzae]]
#[[Chlamydophila pneumoniae]]
#[[Influenza|Influenza A and B]], [[adenovirus]], [[respiratory syncytial virus]], [[parainfluenza]]
| style="padding: 5px 5px; background: #F5F5F5;" |
#[[Streptococcus pneumoniae]]
#[[Mycoplasma pneumoniae]]
#[[Haemophilus influenzae]]
#[[Legionella]]
#[[Aspiration]]
#[[Influenza|Influenza A and B]], [[adenovirus]], [[respiratory syncytial virus]], [[parainfluenza]]
#[[Yersinia enterocolitica]]
| style="padding: 5px 5px; background: #F5F5F5;" |
#[[Streptococcus pneumoniae]]
#[[Staphylococcus aureus]]
#[[Legionella]]
#[[Gram-negative bacilli]]
#[[Haemophilus influenzae]]
#[[Acinetobacter baumannii]]
|}
===Common Causes by Age Group===
{| style="border: 0px; font-size: 85%; margin: 3px; width:700px;" align=center
|valign=top|
|+
! style="background: #4479BA; color:#FFF;  width: 100px;" | Age Group
! style="background: #4479BA; color:#FFF;  width: 250px;" | Neonates
! style="background: #4479BA; color:#FFF;  width: 250px;" | Children
! style="background: #4479BA; color:#FFF;  width: 250px;" | Adults
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Bacteria
| style="padding: 5px 5px; background: #F5F5F5;" |
# ''[[Listeria monocytogenes]]''
# ''[[Mycobacterium tuberculosis]]''
| style="padding: 5px 5px; background: #F5F5F5;" |
# ''[[Mycoplasma pneumoniae]]''
# ''[[Chlamydophila pneumoniae]]''
# ''[[Legionella pneumophila]]''
# ''[[Chlamydia trachomatis]]''
| style="padding: 5px 5px; background: #F5F5F5;" |
'''Typical Bacteria'''
# ''[[Streptococcus pneumoniae]]''
# ''[[Haemophilus influenzae]]''
# ''[[Escherichia coli]]''
# ''[[Klebsiella pneumoniae]]''
# ''[[Pseudomonas aeruginosa]]''
'''Atypical Bacteria'''
# ''[[Mycoplasma pneumoniae]]''
# ''[[Chlamydophila pneumoniae]]''
# ''[[Legionella pneumophila]]''
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Virus
| style="padding: 5px 5px; background: #F5F5F5;" |
# [[Herpes simplex virus]]
# [[Adenovirus]]
# [[Mumps]]
# [[Enterovirus]]
| style="padding: 5px 5px; background: #F5F5F5;" |
# [[Respiratory syncytial virus|Respiratory syncytial virus (RSV)]]
# [[Metapneumovirus]]
# [[Adenovirus]]
# [[Parainfluenza]]
# [[Influenza]]
# [[Rhinovirus]]
| style="padding: 5px 5px; background: #F5F5F5;" |
# [[Influenza]]
# [[Parainfluenza]]
# [[Respiratory syncytial virus|Respiratory syncytial virus (RSV)]]
# [[Metapneumovirus]]
# [[Adenovirus]]
|}
* Newborn [[infant]]s, [[children]], and [[adult]]s are at risk for different spectrums of disease causing microorganisms.
* In addition, adults with [[chronic (medicine)|chronic]] illnesses, who live in certain parts of the world, who reside in [[nursing home]]s, who have recently been treated with [[antibiotic]]s, or who are [[alcoholism|alcoholics]] are at risk for unique infections.
===Infants and Newborns===
* GBS causes at least 50% of cases of CAP in the first week of life.{{ref|Webber}}
* Other bacterial causes in the newborn period include ''[[Listeria monocytogenes]]'' and ''[[Mycobacterium tuberculosis]]''.
* Viral causes like [[herpes simplex virus]] (most common), [[adenovirus]], [[mumps]], and [[enterovirus]].
===Children===
* For the most part, children older than one month are at risk for the same microorganisms as adults.
* Children less than five years are much less likely to have pneumonia caused by ''[[Mycoplasma pneumoniae]]'', ''[[Chlamydophila pneumoniae]]'', or ''[[Legionella|Legionella pneumophila]]''.<ref name="Shachor-Meyouhas-2012">{{Cite journal  | last1 = Shachor-Meyouhas | first1 = Y. | last2 = Arad-Cohen | first2 = N. | last3 = Zaidman | first3 = I. | last4 = Gefen | first4 = A. | last5 = Kassis | first5 = I. | title = [Legionella pneumonia in a child with leukemia]. | journal = Harefuah | volume = 151 | issue = 8 | pages = 479-82, 496 | month = Aug | year = 2012 | doi =  | PMID = 23350295 }}</ref>
* In contrast, older children and teenagers are more likely to acquire ''[[Mycoplasma pneumoniae]]'' and ''[[Chlamydophila pneumoniae]]'' than adults.{{ref|Wubbel}}
* A unique cause of CAP in this group is ''[[Chlamydia trachomatis]]'', which is acquired during birth but does not cause pneumonia until 2-4 weeks later.
* Common viruses include [[respiratory syncytial virus|respiratory syncytial virus (RSV)]], [[metapneumovirus]], [[adenovirus]], [[parainfluenza]], [[influenza]], and [[rhinovirus]].
* [[RSV]] in particular is a common source of illness and hospitalization.{{ref|Abzug}}
* Fungi and parasites are not typically encountered in otherwise healthy infants, though maternally-derived [[syphilis]] can be a cause of CAP in this age group.
===Adults===
The causes of CAP in adults are outlined in the following categories.
======Viruses======
* Viruses account for about 20% cases of CAP.
* Common viruses are [[influenza]], [[parainfluenza]], [[respiratory syncytial virus]], [[metapneumovirus]], and [[adenovirus]].
* Less common viruses include [[varicella|chicken pox]], [[SARS]], [[H5N1|avian flu]], and [[hantavirus]].{{ref|Roux}}
======''Streptococcus pneumoniae''======
* ''[[Streptococcus pneumoniae]]'' is the most common cause of community-acquired pneumonia.
* [[Aspiration pneumonia]] is most commonly caused by [[anaerobic]] organisms.
* Prior to the development of antibiotics and vaccination, it was a leading cause of death.
* Traditionally, it was highly sensitive to [[penicillin]], but during the 1970s resistance to multiple antibiotics began to develop.
* Current strains of drug resistant ''[[Streptococcus pneumoniae]]'' (DRSP) are common, accounting for twenty percent of all [[streptococcal]] infections.
* risk factors for DRSP in adults include: being older than 65, having exposure to children in day care, [[alcoholism]], other severe underlying disease, or recent treatment with antibiotics; individuals exposed to these risk factors should initially be treated with antibiotics effective against DRSP.{{ref|Ruhe}}
======Atypical Organisms======
* ''[[Mycoplasma pneumoniae]]'', ''[[Chlamydophila pneumoniae]]'', and ''[[Legionella|Legionella pneumophila]]'' are often grouped as atypical pneumonia. Community-acquired pneumonia caused by these agents present insidiously, with a non-productive [[cough]] and prominent extra-pulmonary complaints, such as [[myalgia]]s and [[diarrhea]] (lack the typical [[pneumonia]] symptoms of [[fever]], [[cough]], and [[sputum]]).
* ''[[Mycoplasma pneumoniae]]'' is often referred to as "walking pneumonia." It is transmitted via respiratory droplets and is common among healthy individuals in close contact with one another in settings such as dormitories or military barracks.
* Atypical organisms are more difficult to grow and respond to different antibiotics; they were discovered more recently than the typical bacteria discovered in the early twentieth century.
======''Haemophilus influenzae''======
* ''[[Haemophilus influenzae]]'' used to be a common bacterial cause of CAP.
* First discovered in 1892, it was initially believed to be the cause of [[influenza]] because it commonly causes CAP in people who have suffered recent lung damage from viral pneumonia.
======Enteric Gram-Negative Bacteria======
* Enteric bacteria such as ''[[Escherichia coli]]'' and ''[[Klebsiella pneumoniae]]'' may cause commnity-acquired penumonia.
* risk factors in adults for infection include: living in a [[nursing home]], serious [[heart disease|heart]] and [[lung disease]], and recent antibiotic use; these individuals should initially be treated with antibiotics effective against enteric Gram-negative bacteria.
======''Pseudomonas aeruginosa''======
* ''[[Pseudomonas aeruginosa]]'' is an uncommon cause of CAP, but it is a particularly difficult bacteria to treat.
* Individuals who are malnourished, have [[bronchiectasis]], are on [[corticosteroids]], or have recently had strong antibiotics for a week or more, should initially be treated with antibiotics effective against ''[[Pseudomonas aeruginosa]]''.{{ref|Lieberman}}
======Special Situations======
* [[Coccidioidomycosis|Coccidioides spp.]] are common in southwestern area of the United States.
* [[Anaerobic]] infection is common in alcoholics. [[Pneumococcal]] pneumonia remains the most common cause of CAP in alcoholics.
* [[Psittacosis]] (caused by ''[[Chlamydophila psittaci]]'') should be considered in the patient with exposure to birds or bird droppings.
* [[Anaerobes]] are common in patients with poor dental hygiene and a suspected large volume of aspiration.
* ''[[Streptococcus pneumoniae]]'', ''[[Haemophilus influenzae]]'', ''[[Moraxella catarrhalis]]'', and ''[[Legionella]]'' species are the common causes of community acquired pneumonia in those with chronic obstructive pulmonary disorders and smokers.
* ''[[Streptococcus pneumoniae]]'', [[Gram-negative bacilli]], ''[[Haemophilus influenzae]]'', ''[[Staphylococcus aureus]]'', [[anaerobe]]s, and ''[[Chlamydophila pneumoniae]]'' are more common in nursing home residents.
* ''[[Streptococcus pneumoniae]]'', ''[[Haemophilus influenzae]]'', and ''[[Mycobacterium tuberculosis]]'' are common pathogens in early stages of [[HIV]], whereas, ''[[Pneumocystis jiroveci]]'', ''[[Histoplasma]]'', and ''[[Cryptococcus]]'' are commonly seen in late stages [[HIV]].
* In patients with structural lung disease such as [[bronchiectasis]] and [[cystic fibrosis]], ''[[Pseudomonas aeruginosa]]'', ''[[Burkholderia cepacia]]'', and ''[[Staphylococcus aureus]]'' are the common pathogens involved.
======Aspiration Pneumonia======
* Incompetent [[swallowing]] mechanism, as can be found in neurological disease (a common cause being [[cerebrovascular accident|strokes]]) or while a person is [[Drunkenness|intoxicated]].
* [[Iatrogenic]] causes such as [[general anaesthesia]] for an [[Surgery|operation]]. Patients are therefore instructed to be [[nil per os]] (NPO) for at least four hours before surgery.
* Whether [[aspiration pneumonia]] represents a true bacterial infection or a chemical inflammatory process remains the subject of significant controversy.
===Causes by Organ System===
{|style="width:80%; height:100px" border="1"
|style="height:100px"; style="width:25%" border="1" bgcolor="LightSteelBlue" |'''Cardiovascular'''
|style="height:100px"; style="width:75%" border="1" bgcolor="Beige" | No underlying causes
|-
|bgcolor="LightSteelBlue"| '''Chemical/Poisoning'''
|bgcolor="Beige"| No underlying cause
|-bgcolor="LightSteelBlue"
| '''Dental'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Dermatologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Drug Side Effect'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Ear Nose Throat'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Endocrine'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Environmental'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Gastroenterologic'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Genetic'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Hematologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Iatrogenic'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Infectious Disease'''
|bgcolor="Beige"| [[Acinetobacter baumannii]], [[Actinomycosis]], [[Adenovirus|Adenovirus (serotype 1, 2, 3, 4, 5, 7, 14, 21, 35)]], [[AIDS|AIDS-related opportunistic infections]], [[Aspergillosis]], [[Aspiration]], [[Bacillus anthracis]], [[Bird flu|Bird flu (avian influenza)]], [[Blastomycosis]], [[Burkholderia cepacia]], [[Burkholderia pseudomallei]], [[Chlamydophila pneumoniae]], [[Chickenpox]], [[Coccidioides immitis]], [[Coronavirus]], [[Coxiella burnetii|Coxiella burnetii (Q fever)]], [[Cryptococcus neoformans]], [[Cytomegalovirus]], [[Escherichia coli]], [[Enterovirus]], [[Francisella tularensis]], [[Gram-negative bacilli]], [[Haemophilus influenzae]], [[Influenza A virus subtype H1N1|H1N1 flu]], [[Hantavirus]], [[Herpes simplex virus]], [[Histoplasma capsulatum]], [[Histoplasmosis]], [[Human bocavirus]], [[parechovirus|Human parechovirus types 1, 2, and 3]], [[Influenza]], [[Klebsiella pneumoniae]], [[Legionella micdadei]], [[Legionella pneumophila|Legionella pneumophila (Legionnaires' disease)]], [[Listeria monocytogenes]], [[Mycoplasma pneumoniae]], [[Measles]], [[Melioidosis]], [[Metapneumovirus]], [[Middle East respiratory syndrome coronavirus]], [[Moraxella catarrhalis]], [[Mumps]], [[Mycobacterium avium-intracellulare]], [[Mycobacterium haemophilum]], [[Mycobacterium kansasii]], [[Neisseria meningitidis]], [[Coronavirus|New Haven coronavirus]], [[Nocardia]], [[Paragonimiasis]], [[Parainfluenza]], [[Pneumocystis jiroveci]], [[Pneumonic plague]], [[Proteus]], [[Pseudomonas aeruginosa]], [[Chlamydophila psittaci|Chlamydophila psittaci (psittacosis)]], [[Rat-bite fever]], [[Respiratory syncytial virus|Respiratory syncytial virus (RSV)]], [[Rhinovirus]], [[Rhodococcus equi]], [[Streptococcus pneumoniae|Streptococcus pneumoniae (pneumococcus)]], [[SARS]], [[Serratia]], [[Severe acute respiratory syndrome]], [[Sporotrichosis ]], [[Staphylococcus aureus]], [[Streptococcus agalactiae|Streptococcus agalactiae (group B streptococcus)]], [[Streptococcus pyogenes|Streptococcus pyogenes (group A streptococcus)]], [[Streptococcus pneumoniae]], [[Swine flu]], [[Toxocariasis ]], [[Toxoplasma gondii]], [[Trichosporon ]], [[Trypanosomiasis]], [[Typhus]], [[Varicella-zoster virus]], [[Yersinia enterocolitica]], [[Yersinia pestis]], [[Zygomycosis]]
|-bgcolor="LightSteelBlue"
| '''Musculoskeletal/Orthopedic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Neurologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Nutritional/Metabolic'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Obstetric/Gynecologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Oncologic'''
|bgcolor="Beige"| No underlying cause
|-bgcolor="LightSteelBlue"
| '''Ophthalmologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Overdose/Toxicity'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Psychiatric'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Pulmonary'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Renal/Electrolyte'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Rheumatology/Immunology/Allergy'''
|bgcolor="Beige"| No underlying cause
|-
|-bgcolor="LightSteelBlue"
| '''Sexual'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Trauma'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Urologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Miscellaneous'''
|bgcolor="Beige"| No underlying cause
|-
|}
===Causes in Alphabetical Order===
{{col-begin|width=80%}}
{{col-break|width=33%}}
* [[Acinetobacter baumannii]]
* [[Actinomycosis]]
* [[Adenovirus|Adenovirus (serotype 1, 2, 3, 4, 5, 7, 14, 21, 35)]]
* [[AIDS|AIDS-related opportunistic infections]]
* [[Aspergillosis]]
* [[Aspiration]]
* [[Bacillus anthracis]]
* [[Bird flu|Bird flu (avian influenza)]]
* [[Blastomycosis]]
* [[Burkholderia cepacia]]
* [[Burkholderia pseudomallei]]
* [[Chlamydophila pneumoniae]]
* [[Chickenpox]]
* [[Coccidioides immitis]]
* [[Coronavirus]]
* [[Coxiella burnetii|Coxiella burnetii (Q fever)]]
* [[Cryptococcus neoformans]]
* [[Cytomegalovirus]]
* [[Escherichia coli]]
* [[Enterovirus]]
* [[Francisella tularensis]]
* [[Gram-negative bacilli]]
* [[Influenza A virus subtype H1N1|H1N1 flu]]
* [[Haemophilus influenzae]]
* [[Hantavirus]]
* [[Herpes simplex virus]]
* [[Histoplasma capsulatum]]
{{col-break|width=33%}}
* [[Histoplasmosis]]
* [[Human bocavirus]]
* [[parechovirus|Human parechovirus types 1, 2, and 3]]
* [[Influenza]]
* [[Klebsiella pneumoniae]]
* [[Legionella micdadei]]
* [[Legionella pneumophila|Legionella pneumophila (Legionnaires' disease)]]
* [[Listeria monocytogenes]]
* [[Mycoplasma pneumoniae]]
* [[Measles]]
* [[Melioidosis]]
* [[Metapneumovirus]]
* [[Middle East respiratory syndrome coronavirus]]
* [[Moraxella catarrhalis]]
* [[Mumps]]
* [[Mycobacterium avium-intracellulare]]
* [[Mycobacterium haemophilum]]
* [[Mycobacterium kansasii]]
* [[Mycoplasma pneumoniae]]
* [[Neisseria meningitidis]]
* [[Coronavirus|New Haven coronavirus]]
* [[Nocardia]]
* [[Paragonimiasis]]
* [[Parainfluenza]]
* [[Pneumocystis jiroveci]]
* [[Pneumonic plague]]
{{col-break|width=33%}}
* [[Proteus]]
* [[Pseudomonas aeruginosa]]
* [[Chlamydophila psittaci|Chlamydophila psittaci (psittacosis)]]
* [[Rat-bite fever]]
* [[Respiratory syncytial virus|Respiratory syncytial virus (RSV)]]
* [[Rhinovirus]]
* [[Rhodococcus equi]]
* [[Streptococcus pneumoniae|Streptococcus pneumoniae (pneumococcus)]]
* [[SARS]]
* [[Serratia]]
* [[Severe acute respiratory syndrome]]
* [[Sporotrichosis ]]
* [[Staphylococcus aureus]]
* [[Streptococcus agalactiae|Streptococcus agalactiae (group B streptococcus)]]
* [[Streptococcus pyogenes|Streptococcus pyogenes (group A streptococcus)]]
* [[Streptococcus pneumoniae]]
* [[Swine flu]]
* [[Toxocariasis ]]
* [[Toxoplasma gondii]]
* [[Trichosporon ]]
* [[Trypanosomiasis]]
* [[Typhus]]
* [[Varicella-zoster virus]]
* [[Yersinia enterocolitica]]
* [[Yersinia pestis]]
* [[Zygomycosis]]
{{col-end}}


===Causes in Aphabetical Order===
===Causes in Aphabetical Order===

Revision as of 16:30, 1 March 2018

Pneumonia Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Pneumonia from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Criteria

Diagnostic Algorithm

History and Symptoms

Physical Examination

Laboratory Findings

Chest X Ray

CT

Other Imaging Findings

Treatment

Medical Therapy

Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Pneumonia causes On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Pneumonia causes

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Pneumonia causes

CDC onPneumonia causes

Pneumonia causes in the news

Blogs on Pneumonia causes

Directions to Hospitals Treating Pneumonia

Risk calculators and risk factors for Pneumonia causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: , Hamid Qazi, MD, BSc [2], Priyamvada Singh, M.D. [3]; Alejandro Lemor, M.D. [4]; Ogheneochuko Ajari, MB.BS, MS [5]

Overview

Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, parasites, and chemical or physical injury to the lungs. The etiology will depend upon various factors such as age, immune status, geographical area, and comorbidities.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

Common Causes

Causes by Organ System

Cardiovascular Austrian triad, Dressler syndrome
Chemical/Poisoning Ammonia inhalation, chlorine gas, chloroacetophenone, CS gas, formalin vapors inhalation, gold salts, gold, hydrocarbon poisoning, hydrogen sulfide, nitrogen dioxide, ozone inhalation, phosgene inhalation, sulfur dioxide inhalation
Dental No underlying causes
Dermatologic Chediak-Higashi syndrome, dermatomyositis, Lenz-Majewski hyperostotic dwarfism syndrome, systemic lupus erythematosus , zygomycosis
Drug Side Effect Acebutolol, amiodarone, belimumab, bleomycin, blinatumomab, boceprevir, bucillamine, captopril, carbamazepine, ceritinib, crizotinib, cyclophosphamide, dihydroergocryptine, dihydroergotamine, docetaxel, dornase alfa, dronedarone, enfuvirtide,ethanolamine oleate, felbamate, gemcitabine, hexamethonium, idelalisib, iloperidone, interferon alfacon-1, mefloquine, mesalazine, methotrexate, minocycline, nilutamide, nitrofurantoin, nivolumab, olaparib, paclitaxel, pegylated interferon alfa-2b, pembrolizumab, penicillamine, phenytoin, rituximab, sulfasalazine, ticlopidine, trametinib
Ear Nose Throat Epiglottitis, laryngeal cleft
Endocrine No underlying causes
Environmental Asbestosis, brucella abortus, byssinosis, extrinsic allergic alveolitis, occupational lung disease, pneumoconiosis, talc pneumoconiosis
Gastroenterologic Achalasia, cystic fibrosis, esophageal atresia, gastroesophageal reflux, infantile dysphagia, inflammatory bowel disease, zygomycosis
Genetic Aicardi syndrome, ataxia telangiectasia, Becker's muscular dystrophy, Chediak-Higashi syndrome, chronic granulomatous disease, congenital pulmonary anomalies, Cornelia de Lange syndrome, cystic fibrosis, Down syndrome, Duchenne muscular dystrophy, Jeune's syndrome, Kartagener syndrome, Machado-Joseph disease, Marie type ataxia, Nezelof syndrome, osteogenesis imperfecta, pulmonary surfactant-associated protein C, SCID, Simpson-Golabi-Behmel syndrome, WHIM syndrome, x-linked agammaglobulinemia
Hematologic Agranulocytosis, atransferrinemia, infantile hypophosphatasia, multiple myeloma, neutropenia, pseudophosphatasia, sickle cell anemia, x-linked agammaglobulinemia
Iatrogenic Anesthesia, general anaesthesia, radiotherapy
Infectious Disease Achromobacter xylosoxidans, acinetobacter baumannii, actinomycosis, acute bronchitis, acute upper respiratory infection, acute viral nasopharyngitis (common cold), adenovirus, adiaspiromycosis, allergic bronchopulmonary aspergillosis, anaerobes, anthrax, aspergillosis, aspergillus, aspiration pneumonia, aspiration, atypical pneumonia, aureobasidium pullulans exposure, Austrian triad, avian influenza, bacillus anthracis, blastomyces dermatitidis, blastomycosis, bocavirus, bordetella pertussis, brucella abortus, burkholderia cepacia, burkholderia pseudomallei, candida, chemical pneumonia, chicken pox, chlamydia trachomatis, chlamydophila pneumoniae, chlamydophila psittaci, coccidioides immitis, coccidioidomycosis, common cold, community-acquired pneumonia, coronavirus, coxiella burnetii, cryptococcus neoformans, cytomegalovirus, encephalitozoon cuniculi infection, enterobacter, enterovirus, eosinophilic pneumonia, epiglottitis, escherichia coli, flu, francisella tularensis, gram-negative bacilli, Group A streptococcal infection, Group B streptococcal infection, haemophilus influenzae, hantavirus, herpes simplex virus, histoplasma capsulatum, histoplasmosis, HIV, human T-lymphotropic virus, hypersensitivity pneumonitis, influenza, Kartagener syndrome, klebsiella pneumoniae, klebsiella, Kyasanur-Forrest disease, legionella pneumophila, Legionnaires' disease, leptospira, listeria monocytogenes, listeriosis, lung abscess, malignant buotonneuse fever, measles, melioidosis, metapneumovirus, methicillin-resistant staphylococcus aureus, Middle East respiratory syndrome coronavirus infection, moraxella catarrhalis, MSSA, mumps, mycobacterium avium-intracellulare, mycobacterium haemophilum, mycobacterium kansasii, mycobacterium tuberculosis, mycoplasma hominis, mycoplasma pneumoniae, neisseria meningitidis, nocardia, nocardiosis, paracoccidioides, paragonimiasis, parainfluenza, parechovirus, pertussis, plague, pleurisy, pneumococcal pneumonia, pneumococcus, pneumocystis jiroveci, pneumocystis jirovecii pneumonia, pneumonic plague, proteus, pseudomonas aeruginosa, pseudomonas pseudomallei, psittacosis, Q fever, rat-bite fever, respiratory syncytial virus, rheumatic fever, rhinovirus, rhodococcus equi, rickettsia rickettsii, serratia, severe acute respiratory syndrome, sporotrichosis, staphylococcus aureus, stenotrophomonas maltophilia, sterile pneumonitis, streptococcus agalactiae, streptococcus group A, streptococcus pneumoniae, swine flu, torulopsis, toxocariasis, toxoplasma gondii, treponema pallidum, trichosporon, trypanosomiasis, tularemia, typhoid fever, typhus, ureaplasma urealyticum, varicella, varicella-zoster virus, whooping cough, yersinia enterocolitica, yersinia pestis, zygomycosis
Musculoskeletal/Orthopedic Becker's muscular dystrophy, Duchenne muscular dystrophy, idiopathic myopathy, Jeune's syndrome, Lenz-Majewski hyperostotic dwarfism syndrome, osteogenesis imperfecta, polymyositis, skeletal dysplasia
Neurologic Aicardi syndrome, Alzheimer's disease, Arnold-Chiari malformation, ataxia telangiectasia, cerebrovascular accident, corticobasal degeneration, idiopathic myopathy, idiopathic Parkinson's disease, Machado-Joseph disease, Marie type ataxia, Mobius syndrome, neisseria meningitidis, Parkinson's disease, persistent vegetative state, precocious myoclonic encephalopathy, progressive supranuclear palsy
Nutritional/Metabolic Pulmonary surfactant-associated protein C
Obstetric/Gynecologic Gastric content aspiration
Oncologic Bronchogenic carcinoma, lung cancer, malignancy, multiple myeloma
Ophthalmologic Aicardi syndrome, multiple pterygium syndrome
Overdose/Toxicity Chemical pneumonia, cocaine abuse
Psychiatric Alzheimer's disease, cocaine abuse, corticobasal degeneration
Pulmonary Acute bronchitis, acute interstitial pneumonia, acute respiratory distress syndrome, acute upper respiratory infection, acute viral nasopharyngitis (common cold), allergic bronchopulmonary aspergillosis, asbestosis, aspiration pneumonia, aspiration, atypical pneumonia, Austrian triad, bronchiectasis, bronchogenic carcinoma, byssinosis, chemical pneumonia, cholesterol pneumonia, common cold, community-acquired pneumonia, congenital pulmonary anomalies, cryptogenic organizing pneumonia, eosinophilic pneumonia, extrinsic allergic alveolitis, flu, gastric content aspiration, Hamman-Rich syndrome,hospital-acquired pneumonia hypersensitivity pneumonitis, interstitial lung disease, Kartagener syndrome, Legionnaires' disease, lipoid pneumonia, Löffler's syndrome, lung abscess, lung cancer, lymphocytic interstitial pneumonia, mycobacterium tuberculosis, neonatal pneumonia, Pittsburgh pneumonia, pleurisy, pneumococcal pneumonia, pneumoconiosis, severe acute respiratory syndrome, sterile pneumonitis, usual interstitial pneumonia, whooping cough, Williams-Campbell syndrome
Renal/Electrolyte Chronic renal failure, systemic lupus erythematosus
Rheumatology/Immunology/Allergy Allergic bronchopulmonary aspergillosis, byssinosis, chronic granulomatous disease, common variable immunodeficiency, dermatomyositis, extrinsic allergic alveolitis, hyper-IgE syndrome, hyper-IgM syndrome, hypersensitivity pneumonitis, IgG deficiency, immunoglobulin G subclass deficiency, Nezelof syndrome, polymyositis, rheumatic fever, rheumatoid arthritis, SCID, Sjogren's syndrome, Still's disease, systemic lupus erythematosus, systemic sclerosis, WHIM syndrome, x-linked agammaglobulinemia
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying causes

Community Acquired Pneumonia

Causes

Most Common Etiologies for Community-Acquired Pneumonia [1][2][3]

Outpatient Inpatient (non-ICU) Inpatient (ICU)
  1. Streptococcus pneumoniae
  2. Mycoplasma pneumoniae
  3. Haemophilus influenzae
  4. Chlamydophila pneumoniae
  5. Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
  1. Streptococcus pneumoniae
  2. Mycoplasma pneumoniae
  3. Haemophilus influenzae
  4. Legionella
  5. Aspiration
  6. Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
  7. Yersinia enterocolitica
  1. Streptococcus pneumoniae
  2. Staphylococcus aureus
  3. Legionella
  4. Gram-negative bacilli
  5. Haemophilus influenzae
  6. Acinetobacter baumannii

Common Causes by Age Group

Age Group Neonates Children Adults
Bacteria
  1. Listeria monocytogenes
  2. Mycobacterium tuberculosis
  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
  4. Chlamydia trachomatis

Typical Bacteria

  1. Streptococcus pneumoniae
  2. Haemophilus influenzae
  3. Escherichia coli
  4. Klebsiella pneumoniae
  5. Pseudomonas aeruginosa

Atypical Bacteria

  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
Virus
  1. Herpes simplex virus
  2. Adenovirus
  3. Mumps
  4. Enterovirus
  1. Respiratory syncytial virus (RSV)
  2. Metapneumovirus
  3. Adenovirus
  4. Parainfluenza
  5. Influenza
  6. Rhinovirus
  1. Influenza
  2. Parainfluenza
  3. Respiratory syncytial virus (RSV)
  4. Metapneumovirus
  5. Adenovirus
  • Newborn infants, children, and adults are at risk for different spectrums of disease causing microorganisms.
  • In addition, adults with chronic illnesses, who live in certain parts of the world, who reside in nursing homes, who have recently been treated with antibiotics, or who are alcoholics are at risk for unique infections.

Infants and Newborns

Children

Adults

The causes of CAP in adults are outlined in the following categories.

Viruses
Streptococcus pneumoniae
  • Streptococcus pneumoniae is the most common cause of community-acquired pneumonia.
  • Aspiration pneumonia is most commonly caused by anaerobic organisms.
  • Prior to the development of antibiotics and vaccination, it was a leading cause of death.
  • Traditionally, it was highly sensitive to penicillin, but during the 1970s resistance to multiple antibiotics began to develop.
  • Current strains of drug resistant Streptococcus pneumoniae (DRSP) are common, accounting for twenty percent of all streptococcal infections.
  • risk factors for DRSP in adults include: being older than 65, having exposure to children in day care, alcoholism, other severe underlying disease, or recent treatment with antibiotics; individuals exposed to these risk factors should initially be treated with antibiotics effective against DRSP.[10]
Atypical Organisms
  • Mycoplasma pneumoniae is often referred to as "walking pneumonia." It is transmitted via respiratory droplets and is common among healthy individuals in close contact with one another in settings such as dormitories or military barracks.
  • Atypical organisms are more difficult to grow and respond to different antibiotics; they were discovered more recently than the typical bacteria discovered in the early twentieth century.
Haemophilus influenzae
  • Haemophilus influenzae used to be a common bacterial cause of CAP.
  • First discovered in 1892, it was initially believed to be the cause of influenza because it commonly causes CAP in people who have suffered recent lung damage from viral pneumonia.
Enteric Gram-Negative Bacteria
  • Enteric bacteria such as Escherichia coli and Klebsiella pneumoniae may cause commnity-acquired penumonia.
  • risk factors in adults for infection include: living in a nursing home, serious heart and lung disease, and recent antibiotic use; these individuals should initially be treated with antibiotics effective against enteric Gram-negative bacteria.
Pseudomonas aeruginosa
Special Situations
Aspiration Pneumonia

Causes by Organ System

Cardiovascular No underlying causes
Chemical/Poisoning No underlying cause
Dental No underlying causes
Dermatologic No underlying causes
Drug Side Effect No underlying cause
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying cause
Gastroenterologic No underlying cause
Genetic No underlying cause
Hematologic No underlying causes
Iatrogenic No underlying cause
Infectious Disease Acinetobacter baumannii, Actinomycosis, Adenovirus (serotype 1, 2, 3, 4, 5, 7, 14, 21, 35), AIDS-related opportunistic infections, Aspergillosis, Aspiration, Bacillus anthracis, Bird flu (avian influenza), Blastomycosis, Burkholderia cepacia, Burkholderia pseudomallei, Chlamydophila pneumoniae, Chickenpox, Coccidioides immitis, Coronavirus, Coxiella burnetii (Q fever), Cryptococcus neoformans, Cytomegalovirus, Escherichia coli, Enterovirus, Francisella tularensis, Gram-negative bacilli, Haemophilus influenzae, H1N1 flu, Hantavirus, Herpes simplex virus, Histoplasma capsulatum, Histoplasmosis, Human bocavirus, Human parechovirus types 1, 2, and 3, Influenza, Klebsiella pneumoniae, Legionella micdadei, Legionella pneumophila (Legionnaires' disease), Listeria monocytogenes, Mycoplasma pneumoniae, Measles, Melioidosis, Metapneumovirus, Middle East respiratory syndrome coronavirus, Moraxella catarrhalis, Mumps, Mycobacterium avium-intracellulare, Mycobacterium haemophilum, Mycobacterium kansasii, Neisseria meningitidis, New Haven coronavirus, Nocardia, Paragonimiasis, Parainfluenza, Pneumocystis jiroveci, Pneumonic plague, Proteus, Pseudomonas aeruginosa, Chlamydophila psittaci (psittacosis), Rat-bite fever, Respiratory syncytial virus (RSV), Rhinovirus, Rhodococcus equi, Streptococcus pneumoniae (pneumococcus), SARS, Serratia, Severe acute respiratory syndrome, Sporotrichosis , Staphylococcus aureus, Streptococcus agalactiae (group B streptococcus), Streptococcus pyogenes (group A streptococcus), Streptococcus pneumoniae, Swine flu, Toxocariasis , Toxoplasma gondii, Trichosporon , Trypanosomiasis, Typhus, Varicella-zoster virus, Yersinia enterocolitica, Yersinia pestis, Zygomycosis
Musculoskeletal/Orthopedic No underlying causes
Neurologic No underlying causes
Nutritional/Metabolic No underlying cause
Obstetric/Gynecologic No underlying causes
Oncologic No underlying cause
Ophthalmologic No underlying causes
Overdose/Toxicity No underlying cause
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal/Electrolyte No underlying causes
Rheumatology/Immunology/Allergy No underlying cause
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying cause

Causes in Alphabetical Order

Causes in Aphabetical Order

The unnamed parameter 2= is no longer supported. Please see the documentation for {{columns-list}}.
4

Microbiological Etiology

Typical Bacteria Atypical Bacteria Viruses
  1. Streptococcus pneumoniae
  2. Haemophilus influenzae
  3. Staphylococcus aureus
  4. Escherichia coli
  5. Klebsiella pneumoniae
  6. Pseudomonas aeruginosa
  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
  1. Influenza
  2. Parainfluenza
  3. Respiratory syncytial virus (RSV)
  4. Metapneumovirus
  5. Adenovirus

Most Common Etiologies for Community-Acquired Pneumonia [1][2][3]

Outpatient Inpatient (non-ICU) Inpatient (ICU)
  1. Streptococcus pneumoniae
  2. Mycoplasma pneumoniae
  3. Haemophilus influenzae
  4. Chlamydophila pneumoniae
  5. Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
  1. Streptococcus pneumoniae
  2. Mycoplasma pneumoniae
  3. Haemophilus influenzae
  4. Legionella
  5. Aspiration
  6. Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
  7. Yersinia enterocolitica
  1. Streptococcus pneumoniae
  2. Staphylococcus aureus
  3. Legionella
  4. Gram-negative bacilli
  5. Haemophilus influenzae
  6. Acinetobacter baumannii

Causes by Pathogen

Click here for bacterial pneumonia
Click here for viral pneumonia
Click here for fungal pneumonia

Causes by Age

Common Causes by Age Group
Pathogen Neonates Children Adults
Bacteria
  1. Listeria monocytogenes
  2. Mycobacterium tuberculosis
  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
  4. Chlamydia trachomatis

Typical Bacteria

  1. Streptococcus pneumoniae
  2. Haemophilus influenzae
  3. Escherichia coli
  4. Klebsiella pneumoniae
  5. Pseudomonas aeruginosa

Atypical Bacteria

  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
Virus
  1. Herpes simplex virus
  2. Adenovirus
  3. Mumps
  4. Enterovirus
  1. Respiratory syncytial virus (RSV)
  2. Metapneumovirus
  3. Adenovirus
  4. Parainfluenza
  5. Influenza
  6. Rhinovirus
  1. Influenza
  2. Parainfluenza
  3. Respiratory syncytial virus (RSV)
  4. Metapneumovirus
  5. Adenovirus
  • Newborn infants, children, and adults are at risk for different spectrums of disease causing microorganisms.
  • In addition, adults with chronic illnesses, who live in certain parts of the world, who reside in nursing homes, who have recently been treated with antibiotics, or who are alcoholics are at risk for unique infections.

Infants

Source of Infection

  • Aerosol
  • Aspiration of amniotic fluid
  • Blood-borne infection across the placenta
Newborn

Children

Adults

Viruses

Atypical Organisms

  • Mycoplasma pneumoniae, chlamydophila pneumoniae, and legionella pneumophila are often grouped as atypical pneumonia. Community acquired pneumonia caused by these agents present insidiously, with a non-productive cough and prominent extra-pulmonary complaints, such as myalgias and diarrhea (lack the typical pneumonia symptoms of fever, cough, and sputum).
  • Mycoplasma pneumonia is often called is "walking pneumonia." It is transmitted via respiratory droplets and is common among healthy individuals in close contact with one another, such as dormitories or military barracks.
  • Atypical organisms are more difficult to grow, respond to different antibiotics, and were discovered more recently than the typical bacteria discovered in the early twentieth century.

Streptococcus Pneumoniae

  • Streptococcus pneumoniae is the most common cause of community acquired pneumonia.
  • Aspiration pneumonia is most commonly caused by anaerobic organisms.
  • Prior to the development of antibiotics and vaccination, it was a leading cause of death.
  • Traditionally, it was highly sensitive to penicillin, but during the 1970s resistance to multiple antibiotics began to develop.
  • Current strains of "drug resistant Streptococcus pneumoniae" or DRSP are common, accounting for twenty percent of all streptococcus pneumoniae infections.
  • Adults with risk factors for DRSP including being older than 65, having exposure to children in day care, alcoholism, other severe underlying disease, or recent treatment with antibiotics should initially be treated with antibiotics effective against DRSP.[9]

Hemophilus Influenzae

  • Another common bacterial cause of CAP.
  • First discovered in 1892, it was initially believed to be the cause of influenza because it commonly causes CAP in people who have suffered recent lung damage from viral pneumonia.

Enteric Gram Negative Bacteria

Pseudomonas Aeruginosa

  • Uncommon cause of CAP, but it is a particularly difficult bacteria to treat.
  • Individuals who are malnourished, have bronchiectasis, are on corticosteroids, or have recently had strong antibiotics for a week or more, should initially be treated with antibiotics effective against Pseudomonas aeruginosa.[10]

Special Situations

Aspiration Pneumonia Causes

  • Incompetent swallowing mechanism, such as in neurological disease (a common cause being strokes) or while a person is intoxicated.
  • Iatrogenic causes such as general anaesthesia for an operation. Patients are therefore instructed to be nil per os (NPO) for at least four hours before surgery.
  • Whether aspiration pneumonia represents a true bacterial infection or a chemical inflammatory process remains the subject of significant controversy.

Drug Side Effect

References

  1. 1.0 1.1 Mandell LA, Wunderink RG, Anzueto A, Bartlett JG, Campbell GD, Dean NC, Dowell SF, File TM, Musher DM, Niederman MS, Torres A, Whitney CG (2007). "Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults". Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America. 44 Suppl 2: S27–72. doi:10.1086/511159. PMID 17278083. Retrieved 2012-09-06. Unknown parameter |month= ignored (help)
  2. 2.0 2.1 Wong, KK.; Fistek, M.; Watkins, RR. (2013). "Community-acquired pneumonia caused by Yersinia enterocolitica in an immunocompetent patient". J Med Microbiol. 62 (Pt 4): 650–1. doi:10.1099/jmm.0.053488-0. PMID 23242642. Unknown parameter |month= ignored (help)
  3. 3.0 3.1 Oh, YJ.; Song, SH.; Baik, SH.; Lee, HH.; Han, IM.; Oh, DH. (2013). "A case of fulminant community-acquired Acinetobacter baumannii pneumonia in Korea". Korean J Intern Med. 28 (4): 486–90. doi:10.3904/kjim.2013.28.4.486. PMID 23864808. Unknown parameter |month= ignored (help)
  4. Shachor-Meyouhas, Y.; Arad-Cohen, N.; Zaidman, I.; Gefen, A.; Kassis, I. (2012). "[Legionella pneumonia in a child with leukemia]". Harefuah. 151 (8): 479–82, 496. PMID 23350295. Unknown parameter |month= ignored (help)
  5. Webber S, Wilkinson AR, Lindsell D, Hope PL, Dobson SR, Isaacs D (1990). "Neonatal pneumonia". Arch Dis Child. 65 (2): 207–11. PMC 1792235. PMID 2107797.
  6. Wubbel L, Muniz L, Ahmed A, Trujillo M, Carubelli C, McCoig C; et al. (1999). "Etiology and treatment of community-acquired pneumonia in ambulatory children". Pediatr Infect Dis J. 18 (2): 98–104. PMID 10048679.
  7. Abzug MJ, Beam AC, Gyorkos EA, Levin MJ (1990). "Viral pneumonia in the first month of life". Pediatr Infect Dis J. 9 (12): 881–5. PMID 2177540.
  8. de Roux A, Marcos MA, Garcia E, Mensa J, Ewig S, Lode H; et al. (2004). "Viral community-acquired pneumonia in nonimmunocompromised adults". Chest. 125 (4): 1343–51. PMID 15078744. Check |pmid= value (help).
  9. Ruhe JJ, Myers L, Mushatt D, Hasbun R (2004). "High-level penicillin-nonsusceptible Streptococcus pneumoniae bacteremia: identification of a low-risk subgroup". Clin Infect Dis. 38 (4): 508–14. doi:10.1086/381197. PMID 14765343.
  10. Lieberman D, Schlaeffer F, Boldur I, Lieberman D, Horowitz S, Friedman MG; et al. (1996). "Multiple pathogens in adult patients admitted with community-acquired pneumonia: a one year prospective study of 346 consecutive patients". Thorax. 51 (2): 179–84. PMC 473032. PMID 8711652.

Template:WH Template:WS