From the Guidelines
Complicated pyelonephritis is defined as a kidney infection occurring in patients with underlying structural or functional abnormalities of the urinary tract, or those with conditions that increase the risk of treatment failure or serious complications, as outlined in the 2024 European Association of Urology guidelines 1. This includes patients with:
- Urinary obstruction, such as kidney stones or enlarged prostate
- Indwelling urinary catheters
- Recent urinary tract procedures
- Anatomical abnormalities
- Pregnancy
- Diabetes
- Immunosuppression
- Renal insufficiency It also encompasses infections caused by resistant organisms like ESBL-producing bacteria or those with severe presentations, including sepsis, abscess formation, or emphysematous pyelonephritis. The diagnosis of complicated pyelonephritis involves urinalysis, urine culture, and antimicrobial susceptibility testing, as well as evaluation of the upper urinary tract via ultrasound to rule out urinary tract obstruction or renal stone disease 1. Treatment typically requires broader-spectrum antibiotics than uncomplicated cases, often including intravenous therapy with agents like fluoroquinolones, aminoglycosides, or extended-spectrum cephalosporins, followed by oral therapy based on culture results 1. The total treatment duration is usually 10-14 days, though longer courses may be needed for certain complications, and these infections require close monitoring, possible urological intervention to address underlying abnormalities, and follow-up imaging to ensure resolution of the infection.
From the Research
Definition of Complicated Pyelonephritis
- Complicated pyelonephritis is defined as a symptomatic renal infection occurring in an individual with a structurally or functionally abnormal genitourinary tract 2.
- It is characterized by a wide spectrum of clinical presentations, a wide variety of infecting organisms, and multiple potential complicating genitourinary abnormalities of variable complexity and severity 2.
Characteristics of Complicated Pyelonephritis
- Complicated pyelonephritis can occur in patients with functional or structural abnormalities in the urinary tract, such as those with a history of urinary tract instrumentation or immunocompromised individuals 3.
- The most common causative agent of complicated pyelonephritis is Escherichia coli, although other organisms such as Klebsiella spp and Proteus spp can also be involved 3.
- Patients with complicated pyelonephritis are more likely to develop severe sepsis and septic shock, and have a higher crude mortality and attributable mortality compared to those with uncomplicated pyelonephritis 3, 4.
Comparison with Uncomplicated Pyelonephritis
- Uncomplicated pyelonephritis tends to occur in younger patients, with a higher percentage of E coli infections compared to complicated pyelonephritis 4.
- Patients with uncomplicated pyelonephritis are more likely to be discharged from the emergency department, while those with complicated pyelonephritis have longer hospital lengths of stay and are more likely to require admission 4.
- The rates of admission and orders for urine and blood cultures are significantly higher in patients with complicated pyelonephritis compared to those with uncomplicated pyelonephritis 4.