Editing Pneumonia (section)

===Bacteria===
{{Main|Bacterial pneumonia}}
[[File:MRSAPneumoCT.png|thumb|Cavitating pneumonia due to MRSA as seen on a CT scan]]
Bacteria are the most common cause of [[community-acquired pneumonia]] (CAP), with ''Streptococcus pneumoniae'' isolated in nearly 50% of cases.<ref name=Rad07/><ref name=EOP10>{{cite journal | vauthors = Anevlavis S, Bouros D | title = Community acquired bacterial pneumonia | journal = Expert Opinion on Pharmacotherapy | volume = 11 | issue = 3 | pages = 361–74 | date = February 2010 | pmid = 20085502 | doi = 10.1517/14656560903508770 | s2cid = 24376187 }}</ref> Other commonly isolated bacteria include ''[[Haemophilus influenzae]]'' in 20%, ''[[Chlamydophila pneumoniae]]'' in 13%, and ''Mycoplasma pneumoniae'' in 3% of cases;<ref name=Rad07/> ''[[Staphylococcus aureus]]''; ''[[Moraxella catarrhalis]]''; and ''[[Legionella pneumophila]]''.<ref name=EBMED05/> A number of [[drug resistance|drug-resistant]] versions of the above infections are becoming more common, including drug-resistant ''Streptococcus pneumoniae'' (DRSP) and [[methicillin-resistant Staphylococcus aureus|methicillin-resistant ''Staphylococcus aureus'']] (MRSA).<ref name=Clinic2011/>

The spreading of organisms is facilitated by certain risk factors.<ref name=EBMED05/> Alcoholism is associated with ''Streptococcus pneumoniae'', [[anaerobic organism]]s, and ''Mycobacterium tuberculosis''; smoking facilitates the effects of ''Streptococcus pneumoniae'', ''Haemophilus influenzae'', ''Moraxella catarrhalis'', and ''Legionella pneumophila''. Exposure to birds is associated with ''[[Chlamydia psittaci]]''; farm animals with ''[[Coxiella burnetti]]''; aspiration of stomach contents with anaerobic organisms; and [[cystic fibrosis]] with ''[[Pseudomonas aeruginosa]]'' and ''Staphylococcus aureus''.<ref name=EBMED05/> ''Streptococcus pneumoniae'' is more common in the winter,<ref name=EBMED05/> and it should be suspected in persons aspirating a large number of anaerobic organisms.<ref name=Clinic2011/>