- Typically GNRs (e coli in particular) from an ascending urinary tract infection
- Can be other GNRs (including resistant organisms), enterococcus, other
- Hematogenous spread (e.g. from Staph bacteremia) much less common
- Untreated lower urinary tract infection (ascends)
- Impaired drainage of kidney from: obstructing stone, ureteral stricture/fibrosis, bladder outlet obstruction, other
- Young women (15-30); Older adults (> 60)
- Chronically infected stone or foreign body in urinary tract
- Immuno-compromised
- Acute low back/flank pain
- Sometimes perceived as radiating towards the abdomen
- Urinary frequency
- Pain on flank palpation
- Can be quite ill, w/sepsis physiology (i.e. tachycardia, hypotension, confusion, hypo-perfusion)