Editing Pneumonia (section)

===Microbiology===
In people managed in the community, determining the causative agent is not cost-effective and typically does not alter management.<ref name=Develop11/> 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.<ref name=BTS09/> Microbiological evaluation is also indicated in severe pneumonia, alcoholism, [[asplenia]], immunosuppression, HIV infection, and those being empirically treated for MRSA of pseudomonas.<ref name="Elena 2015"/><ref name=Met2019>{{cite journal | vauthors = Metlay JP, Waterer GW, Long AC, Anzueto A, Brozek J, Crothers K, Cooley LA, Dean NC, Fine MJ, Flanders SA, Griffin MR, Metersky ML, Musher DM, Restrepo MI, Whitney CG | title = Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America | journal = American Journal of Respiratory and Critical Care Medicine | volume = 200 | issue = 7 | pages = e45–e67 | date = October 2019 | pmid = 31573350 | pmc = 6812437 | doi = 10.1164/rccm.201908-1581ST }}</ref> 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 (biology)|colonisation]] of respiratory tract.<ref name="Elena 2015"/> Testing for other specific organisms may be recommended during outbreaks, for public health reasons.<ref name=BTS09/> In those hospitalized for severe disease, both sputum and [[blood cultures]] are recommended,<ref name=BTS09/> as well as testing the urine for [[antigen]]s to ''Legionella'' and ''Streptococcus''.<ref name=IDSA2007/> Viral infections, can be confirmed via detection of either the virus or its antigens with [[Viral culture|culture]] or [[polymerase chain reaction]] (PCR), among other techniques.<ref name=Lancet11/> ''Mycoplasma'', ''Legionella'', ''Streptococcus'', and ''Chlamydia'' can also be detected using PCR techniques on [[bronchoalveolar lavage]] and [[nasopharyngeal swab]].<ref name="Elena 2015"/> The causative agent is determined in only 15% of cases with routine microbiological tests.<ref name=BMJ06/>