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| ==Overview== | | ==Overview== |
| While [[chest X-ray]] and [[pulse oximetry]] are routine tests among all patients with suspected pneumonia, additional laboratory tests (such as blood culture and gram sputum, sputum blood culture and gram stain, urinary antigen tests) are optional tests unless their results might alter the treatment plan.
| | Different laboratory tests might be used in patients with aspiration pneumonia. [[Sputum]] analysis including [[Gram staining|gram stain]] and culture must be done in patients with [[cough]]. [[Arterial blood gas|ABG]] may show acute [[hypoxemia]] and decreased mixed venous [[oxygen saturation]]. [[Complete blood count|CBC]] shows [[leukocytosis]] with left shift or [[leukopenia]], [[anemia]], or [[thrombocytopenia]]. |
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| ==Laboratory Tests== | | ==Laboratory Tests== |
| {| style="border: 0px; font-size: 85%; margin: 3px; width:520px; float:right"
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| |valign=top|
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| |+ '''''Specific indications for additional testing in patients with pneumonia'''''
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| ! style="background: #4479BA; color:#FFF; width: 200px;" | Diagnostic Test
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| ! style="background: #4479BA; color:#FFF; width: 400px;" | Indications
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| | style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Sputum Culture
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| | style="padding: 5px 5px; background: #F5F5F5;" |{{col-begin}}
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| {{col-break}}
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| * ICU admission
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| * Antibiotic therapy failure
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| * Cavitation
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| {{col-break}}
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| * Alcoholic patient
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| * COPD
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| * Pleural effusion
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| {{col-end}}
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| | style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Blood Culture
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| | style="padding: 5px 5px; background: #F5F5F5;" |{{col-begin}}
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| {{col-break}}
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| * ICU admission
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| * Leukopenia
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| * Cavitation
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| * Severe liver disease
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| {{col-break}}
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| * Alcoholic patient
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| * Asplenia
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| * Pleural effusion
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| {{col-end}}
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| | style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Urinary Antigen Test for Pneumococcus
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| | style="padding: 5px 5px; background: #F5F5F5;" |{{col-begin}}
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| {{col-break}}
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| * ICU admission
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| * Leukopenia
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| * Antibiotic therapy failure
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| * Severe liver disease
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| {{col-break}}
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| * Alcoholic patient
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| * Asplenia
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| * Pleural effusion
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| {{col-end}}
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| | style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" | Urinary Antigen Test for Legionella
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| | style="padding: 5px 5px; background: #F5F5F5;" |{{col-begin}}
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| {{col-break}}
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| * ICU admission
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| * Antibiotic therapy failure
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| {{col-break}}
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| * Alcoholic patient
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| * Recent travel (< 2 weeks)
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| * Pleural effusion
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| {{col-end}}
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| | style="padding: 0px 5px; background: #F5F5F5;" colspan=2| Adapted from IDSA/ATS Guidelines for CAP in Adults<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>
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| ===Routine Tests=== | | ===Routine Tests=== |
| Findings in routine blood tests are based on the severity of the disease and the cause, they can include the following:<ref name="SolomonWunderink2014">{{cite journal|last1=Solomon|first1=Caren G.|last2=Wunderink|first2=Richard G.|last3=Waterer|first3=Grant W.|title=Community-Acquired Pneumonia|journal=New England Journal of Medicine|volume=370|issue=6|year=2014|pages=543–551|issn=0028-4793|doi=10.1056/NEJMcp1214869}}</ref> | | Findings in routine blood tests are based on the severity of the disease and the cause, they can include the following:<ref name="SolomonWunderink2014">{{cite journal|last1=Solomon|first1=Caren G.|last2=Wunderink|first2=Richard G.|last3=Waterer|first3=Grant W.|title=Community-Acquired Pneumonia|journal=New England Journal of Medicine|volume=370|issue=6|year=2014|pages=543–551|issn=0028-4793|doi=10.1056/NEJMcp1214869}}</ref> |
| *[[Leukocytosis]] with left shift (in cases of bacterial pneumonia) | | *[[Complete blood count|CBC]] shows: |
| *[[Leukopenia]] (in cases of atypical pneumonia) | | **[[Leukocytosis]] with left shift (in cases of bacterial pneumonia) |
| *[[Eosinophilia]] (in cases of [[eosinophilic pneumonia]]) | | **[[Leukopenia]] (in cases of atypical pneumonia) |
| *[[Anemia]] | | **[[Eosinophilia]] (in cases of [[eosinophilic pneumonia]]) |
| | **[[Anemia]] |
| | **[[Thrombocytopenia]] |
| *[[Hyponatremia]] | | *[[Hyponatremia]] |
| *[[Thrombocytopenia]]
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| *Elevated [[BUN]] | | *Elevated [[BUN]] |
| *Findings of lactic acidosis (decreased HCO<sub>3</sub>, increased [[lactic acid]] levels) | | *[[ABG]] may show: |
| *[[ABG]]: may show [[hypoxia]] and/or hypercapnea | | **Acute [[hypoxemia]] |
| | **Normal to low partial pressure of [[carbon dioxide]] |
| | **Decreased mixed venous oxygen saturation if a patient is in [[Sepsis|septic shock]] |
| | **Decreased [[Bicarbonate|HCO<sub>3</sub>]] |
| | **High [[Lactic acidosis|lactate level]] if a patient is in [[Sepsis|septic shock]] |
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| ===Sputum Gram Stain and Culture=== | | ===Sputum Gram Stain and Culture=== |
| *Sputum samples should be obtained in all patients with productive [[cough]]. | | *[[Sputum]] samples should be obtained in all patients with productive [[cough]]. |
| *Gram-stain and culture should be performed to assess the causative agent and guide the therapy. | | *[[Gram staining|Gram stain]] and culture should be performed to assess the causative agent and guide the therapy. |
| *In approximately 80% of cases of [[pneumococcal pneumonia]] the sputum culture is positive.<ref name="MusherThorner2014">{{cite journal|last1=Musher|first1=Daniel M.|last2=Thorner|first2=Anna R.|title=Community-Acquired Pneumonia|journal=New England Journal of Medicine|volume=371|issue=17|year=2014|pages=1619–1628|issn=0028-4793|doi=10.1056/NEJMra1312885}}</ref>
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| *However, the general yield of a sputum sample does not exceed 50-60%.
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| ===Blood Culture===
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| *Blood cultures should be obtained for patients with severe disease, those who require hospitalization, and those who fail antibiotic therapy.
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| *Blood cultures may be positive in cases of hematogenous spread, such as S. aureus pneumonia, and in approximately one fourth of patients with [[pneumococcal pneumonia]].
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| {|
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| |[[File:Streptococcus pneumoniae bacterial colonies.jpg|thumb|left|300px|This image depicts the colonial characteristics displayed by Streptococcus pneumoniae bacterial colonies that were grown on primary isolation medium, consisting of trypticase soy agar containing 5% sheep’s blood, as well as 5mg of gentamicin/ml.<br><small>Image obtained from CDC PHIL<ref name=PHIL>{{cite web|url=http://phil.cdc.gov/phil/home.asp| title=CDC Public Health Image Library (PHIL) </ref></small>]]
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| ==Other Laboratory Tests==
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| ===Urine Antigen Test <small><small><ref name="pmid24856525">{{cite journal| author=Couturier MR, Graf EH, Griffin AT| title=Urine antigen tests for the diagnosis of respiratory infections: legionellosis, histoplasmosis, pneumococcal pneumonia. | journal=Clin Lab Med | year= 2014 | volume= 34 | issue= 2 | pages= 219-36 | pmid=24856525 | doi=10.1016/j.cll.2014.02.002 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24856525 }} </ref></small></small>===
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| *Usually used to diagnose [[Legionella]] pneumomnia.
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| *Useful also in the diagnosis of pneumonia caused by ''Streptococcus pneumoniae'', with a sensitivity of 74.6%.<ref name="pmid24976113">{{cite journal| author=Zalacain R, Capelastegui A, Ruiz LA, Bilbao A, Gomez A, Uranga A et al.| title=Streptococcus pneumoniae antigen in urine: diagnostic usefulness and impact on outcome of bacteraemic pneumococcal pneumonia in a large series of adult patients. | journal=Respirology | year= 2014 | volume= 19 | issue= 6 | pages= 936-43 | pmid=24976113 | doi=10.1111/resp.12341 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24976113 }} </ref>
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| *The Legionella urine antigen can be detected 24 hours after the onset of the symptoms.
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| *The more sever the [[Legionella]] disease the higher the sensitivity of the urinary antigen test.
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| *Urinary antigen testing is not recommended for the diagnosis of pneumococcal pneumonia in children due to the high rate of false-positive results.<ref name="pmid21880587">{{cite journal| author=Bradley JS, Byington CL, Shah SS, Alverson B, Carter ER, Harrison C et al.| title=The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America. | journal=Clin Infect Dis | year= 2011 | volume= 53 | issue= 7 | pages= e25-76 | pmid=21880587 | doi=10.1093/cid/cir531 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21880587 }} </ref>
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| ===Polymerase Chain Reaction===
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| *[[Polymerase chain reaction]] ([[PCR]]) is more useful in the diagnosis of [[viral pneumonia|viral]] and [[mycoplasma pneumonia]].
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| ===C-Reactive Protein===
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| *[[C-reactive protein]] ([[CRP]]) may be helpful to differentiate between bacterial from viral pneumonia.
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| *It has been reported that [[CRP]] is elevated (> 100 mg/L) in cases of bacterial pneumonia.<ref name="FlandersStein2004">{{cite journal|last1=Flanders|first1=Scott A|last2=Stein|first2=John|last3=Shochat|first3=Guy|last4=Sellers|first4=Karen|last5=Holland|first5=Miles|last6=Maselli|first6=Judith|last7=Drew|first7=W.Lawrence|last8=Reingold|first8=Art L|last9=Gonzales|first9=Ralph|title=Performance of a bedside c-reactive protein test in the diagnosis of community-acquired pneumonia in adults with acute cough|journal=The American Journal of Medicine|volume=116|issue=8|year=2004|pages=529–535|issn=00029343|doi=10.1016/j.amjmed.2003.11.023}}</ref>
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| ===Procalcitonin===
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| *[[Procalcitonin]] levels are associated with the severity of the pneumonia.
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| *This biomarker also helps to differentiate between bacterial and non-bacterial disease.<ref name="JohanssonKalin2014">{{cite journal|last1=Johansson|first1=Niclas|last2=Kalin|first2=Mats|last3=Backman-Johansson|first3=Carolina|last4=Larsson|first4=Anders|last5=Nilsson|first5=Kristina|last6=Hedlund|first6=Jonas|title=Procalcitonin levels in community-acquired pneumonia – correlation with aetiology and severity|journal=Scandinavian Journal of Infectious Diseases|volume=46|issue=11|year=2014|pages=787–791|issn=0036-5548|doi=10.3109/00365548.2014.945955}}</ref>
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| ==Infectious Diseases Society of America/American Thoracic Society consensus recommendation on diagnostics test for etiology of community-acquired pneumonia in adults. <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>==
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| {{cquote|
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| ===Recommended Diagnostic Tests for Etiology===
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| * Patients with CAP should be investigated for specific pathogens that would significantly alter standard (empirical) management decisions, when the presence of such pathogens is suspected on the basis of clinical and epidemiologic clues. '''(Strong recommendation; level II evidence)'''
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| * Routine diagnostic tests to identify an etiologic diagnosis are optional for outpatients with CAP. (Moderate recommendation; level III evidence)
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| * Pretreatment blood samples for culture and an expectorated sputum sample for stain and culture (in patients with a productive cough) should be obtained from hospitalized patients with the clinical indications, but are optional for patients without these conditions. (Moderate recommendation; level I evidence)
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| * Pretreatment Gram stain and culture of expectorated sputum should be performed only if a good-quality specimen can be obtained and quality performance measures for collection, transport, and processing of samples can be met. (Moderate recommendation; level II evidence)
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| * Patients with severe [[CAP]], as defined in the guideline should at least have blood samples drawn for culture, urinary antigen tests for [[Legionella pneumophila]] and [[Streptococcus pneumoniae]] performed, and expectorated sputum samples collected for culture. For intubated patients, an endotracheal aspirate sample should be obtained. (Moderate recommendation; level II evidence)
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| }}
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| '''For Level of evidence and classes click [[ACC AHA Guidelines Classification Scheme|here]].'''
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| ==References== | | ==References== |
| {{Reflist|2}} | | {{Reflist|2}} |
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| | [[Category:Medicine]] |
| | [[Category:Pulmonology]] |
| | [[Category:Up-To-Date]] |
| | [[Category:Emergency medicine]] |