Pneumonia can be classified by several types
1. whether community acquired or hospital acquired
2. typical and atypical
Most of the hospital acquired type organisms cause atypical pneumonia.
The microorganisms vary in these categories.
hospital acquired pneumonia caused by:-
Most commonly-
- P aeruginosa
- Klebsiella species
- Escherichia coli
- Acinetobacter species
- Staphylococcus aureus, (mrsa)
- Streptococcus pneumoniae
- Haemophilus influenzae
Less-common pathogens-
- Serratia species
- Legionella species (Legionella nosocomial pneumonia occurs only in outbreaks or clusters.)
- Influenza A virus
- Respiratory syncytial virus (RSV)
- Parainfluenza virus
- Adenovirus
Extremely rare causes-
- Enterobacter species
- Stenotrophomonas maltophilia
- Burkholderia cepacia
- Candida species
- Oropharyngeal anaerobes (non- Bacteroides fragilis)
