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Community acquired
a) Typical pneumonia is due to Streptococcus pneumoniae > Hemophilus influenzae.
b) Atypical pneumonia is due to Mycoplasma > Chlamydia. -
Nosocomial is due to gram negative rods e.g. Enterobacteriaceae (E.coli and Klebsiella)
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Aspiration pneumonia is due to Anaerobic infections (Peptostreptococcus, Bacteroides, Prevotella, and Fusobacterium).
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With underlying Chronic alcoholism and COPD is due to Klebsiella pneumoniae.
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With underlying Bronchiectasis and cystic fibrosis is due to Pseudomonas aeruginosa.
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Ventilator associated pneumonia is due to Pseudomonas aeruginos