E coli (UTI) and S aureus (wound infection) are the two most common causes.

Decubitus ulcers, surgical woulds, drains – S aureus (including MRSA), gram Θ anaerobes (Bacteroides, Prevotella, Fusobacterium)

Intravascular catheters – S aureus, S epidermidis (long term), Enterobacter

Mechanical ventilation, endotracheal intubation – Late onset: P aeruginosa, Klebsiella, Acinetobacter, S aureus- New infiltrate on CXR, ↑ sputum production; sweet odor (Pseudomonas)

Renal dialysis unit, needlestick – HBV, HCV

Urinary catheterization – Proteus spp, E coli, Klebsiella- Dysuria, leukocytosis, flank pain or costovertebral angle tenderness

Water aerosols – Legionella