Acute Pyelonephritis
System: Genitourinary Infections · Parent MOC: MOC - Diseases by System
One-Sentence Definition
Infection of the renal pelvis and parenchyma, usually from ascending cystitis pathogens, presenting with fever and flank pain and risk of bacteremia.
Clinical Presentation
- Fever, chills, flank/CVA tenderness, nausea/vomiting ± cystitis symptoms
- Can progress to Bloodstream and Sepsis / septic shock
- Complications: abscess, emphysematous pyelo (diabetics), obstruction
Pathogens
| Context | Organism | Notes |
|---|---|---|
| Community | Escherichia coli | Dominant |
| Other | Klebsiella pneumoniae, Proteus, Enterococcus | Stones ↔ Proteus |
| Healthcare | MDR Enterobacterales, Pseudomonas aeruginosa | Prior abx / catheters |
Pathogenesis
- Ascending infection ± bacteremic seeding; virulence adhesins of UPEC
- Obstruction amplifies severity
Diagnosis
| Step | Test | Note |
|---|---|---|
| UA + culture | Always | Before abx when possible |
| Blood cultures | If febrile / hospitalized | Occult bacteremia common |
| Imaging | CT/US if severe, diabetic, no improvement 48–72h, suspect stone/abscess |
Treatment Principles
- Empiric IV/PO based on severity and local ESBL rates
- Narrow with Antimicrobial Susceptibility Testing
- Longer course than cystitis; source control for obstruction/abscess
- Switch IV→PO when stable
Prevention
- Same behavioral as cystitis; treat/relieve obstruction
- Stewardship to limit MDR selection
Differential / Pitfalls
- Renal colic without infection, PID, pneumonia lower lobe, diverticulitis
- Underestimating MDR risk after recent antibiotics/travel/healthcare
Learning Aids
Clinical Example
Example
Case: 40F, fever 39°C, left CVA tenderness; urine grows E. coli.
Question: How does management differ from Acute Cystitis?
Answer: Systemic infection — culture urine ± blood, broader/longer therapy, assess need for imaging if not improving; watch for bacteremia (Bloodstream and Sepsis).
Related
- Acute Cystitis · Genitourinary Infections
- Escherichia coli · Klebsiella pneumoniae · MOC - Antimicrobial Resistance (AMR)
Active Recall
- Indications to image pyelonephritis?
- Why check local ESBL rates for empiric therapy?
- Link between Proteus and stones?