Renal · Year 2 · from Renal

Case 2: Acute Pyelonephritis

Patient Presentation

Demographics: 35-year-old female

Chief Complaint: Fever, chills, and back pain for 1 day

History of Present Illness: The patient developed dysuria and urinary frequency 4 days ago which she ignored. Yesterday she developed high fever (39.2C), severe rigors, nausea with vomiting, and right flank pain. She feels very ill and has been unable to tolerate oral intake.

Past Medical History:

  • Recurrent UTIs (3 in past year)
  • Otherwise healthy

Physical Examination:

  • Blood pressure: 100/62 mmHg
  • Heart rate: 112 bpm
  • Temperature: 39.4C
  • General: Ill-appearing, diaphoretic
  • Abdomen: Mild diffuse tenderness
  • CVA: Marked right costovertebral angle tenderness
  • Skin: Warm, flushed

Workup and Results

Laboratory Studies:

  • WBC: 18,400/mcL with left shift
  • Creatinine: 1.1 mg/dL
  • Urinalysis: 3+ leukocyte esterase, positive nitrite, >100 WBC/hpf, WBC casts, bacteria
  • Blood cultures: Pending
  • Urine culture: E. coli >100,000 CFU/mL

CT Abdomen/Pelvis:

  • Right kidney enlarged with perinephric stranding
  • No abscess or obstruction
  • No stones

Clinical Image

CT scan demonstrating acute pyelonephritis with enlarged right kidney, perinephric fat stranding, and wedge-shaped areas of decreased enhancement representing areas of infection.

Diagnosis

Acute Pyelonephritis (Upper Urinary Tract Infection)

Features indicating upper tract involvement:

  • Fever and systemic symptoms
  • Flank pain and CVA tenderness
  • WBC casts (pathognomonic for pyelonephritis)

Discussion

This case demonstrates acute pyelonephritis:

  • Upper Tract Indicators: The lecture emphasizes that fever distinguishes upper from lower UTI. WBC casts are pathognomonic for pyelonephritis, localizing infection to the kidney.
  • Bacteremia Risk: The lecture notes that bacteremia occurs in 20-30% of pyelonephritis cases. Blood cultures are indicated when systemic symptoms are present.
  • Hospitalization Criteria: This patient requires hospitalization due to inability to tolerate oral intake, severe systemic symptoms, and hemodynamic instability (tachycardia, borderline hypotension).
  • P Fimbriae: The lecture describes how E. coli P fimbriae enable ascending infection to the kidney by binding to renal epithelium.

Treatment Plan

  1. Admission for IV Antibiotics:
  • Ceftriaxone 1 g IV daily
  • OR Fluoroquinolone if ceftriaxone-resistant
  1. Supportive Care:
  • IV fluid resuscitation
  • Antipyretics
  • Antiemetics
  1. Monitoring:
  • Repeat cultures if no improvement in 48-72 hours
  • Watch for abscess formation
  1. Transition to Oral:
  • After afebrile 24-48 hours
  • Complete 7-10 day total course
  1. Imaging Indication:
  • CT if no improvement in 48-72 hours (rule out abscess/obstruction)

Teaching Points

  1. Fever indicates upper tract infection (pyelonephritis)
  2. WBC casts are pathognomonic for pyelonephritis
  3. Bacteremia occurs in 20-30% of pyelonephritis cases
  4. Hospitalize for severe symptoms, inability to tolerate oral intake, or hemodynamic instability
  5. Evaluate for abscess/obstruction if no improvement in 48-72 hours

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