DDx Pneumonia
- Community-Acquired
Pneumonia:
- Streptococcus pneumoniae
- Haemophilus
influenzae
- Maraxella catarrhalis
- Staphylococcus
aureus
- Legionella
pneumophila
- Enterobacteriaceae
(Klebsiella pneumoniae) and Pseudomonas spp.
- Community-Acquired
Atypical Pneumonia
- Mycoplasma
pneumoniae
- Chlamydia spp. (C.
pneumoniae, C. psittaci, C. trachomatis)
- Coxiella burnetti
(Q fever)
- Viruses:
- RSV (children)
- parainfluenza
virus (children)
- influenza A and B
(adults)
- adenovirus
(military)
- SARS virus
- Nosocomial
pneumonia:
- Gram-negative rods
– Enterobacteriaceae (Klebsiella spp, Serratia marcescens, Escherichia
coli), Pseudomonas spp.
- Staphylococcus
aureus (usually penicillin-resistant)
- Aspiration
pneumonia
- Admixture of:
- Anaerobic oral
flora:
- Bacteroides
- Prevotella
- Fusobacterium
- Peptostreptococcus
- Aerobic bacteria
- Streptococcus
pneumoniae
- Staphylococcus
aureus
- Haemophilus
influenzae
- Pseudomonas
aeruginosa
- Chronic pneumonia
- Nocardia
- Actinomyces
- Granulomatous:
- Mycobacterium
tuberculosis
- atypical
mycobacteria
- Histoplasma
capsulatum
- Coccidioides
immitis
- Blastomyces
dermatitidis
- Necrotizing
pneumonia and Lung abscess
- Anaerobic bacteria
(extremely common), with or without mixed aerobic infection
- Staphylococcus
aureus
- Klebsiella
pneumoniae
- Streptococcus
pyogenes
- Type 3 pneumococcus
- Pneumonia in the
Immunocompromised:
- CMV
- Pneumocystis
carinii
- Mycobacterium avium-intracellulare
- Invasive
aspergillosis
- Invasive
candidiasis
- “usual” bacterial,
viral, and fungal organisms