From the Guidelines
Pyelonephritis typically presents with fever, flank pain, and systemic symptoms, and its diagnosis is primarily clinical, with laboratory findings and imaging studies used to support the diagnosis and rule out complications. The signs and symptoms of pyelonephritis can vary, but patients often experience fever (often >38°C), flank pain or costovertebral angle tenderness, and systemic symptoms like chills, nausea, and vomiting 1. These may be accompanied by lower urinary tract symptoms including dysuria (painful urination), frequency, urgency, and hematuria (blood in urine) 1. Some patients, particularly elderly individuals, may present with altered mental status, confusion, or nonspecific symptoms without the classic flank pain.
Key Symptoms and Signs
- Fever (often >38°C)
- Flank pain or costovertebral angle tenderness
- Systemic symptoms like chills, nausea, and vomiting
- Lower urinary tract symptoms including dysuria, frequency, urgency, and hematuria
- Altered mental status, confusion, or nonspecific symptoms in elderly individuals
Laboratory findings often show pyuria (white blood cells in urine), bacteriuria, and elevated inflammatory markers like C-reactive protein and white blood cell count 1. The symptoms result from kidney infection and inflammation, typically caused by bacteria ascending from the lower urinary tract, most commonly Escherichia coli 1. Prompt recognition of these symptoms is crucial, as pyelonephritis requires appropriate antibiotic therapy to prevent complications like sepsis or kidney abscess. According to the European Association of Urology guidelines, fluoroquinolones and cephalosporins are the only antimicrobial agents that can be recommended for oral empiric treatment of uncomplicated pyelonephritis 1.
Diagnostic Approach
- Urinalysis, including assessment of white and red blood cells and nitrite
- Urine culture and antimicrobial susceptibility testing
- Evaluation of the upper urinary tract via ultrasound to rule out urinary tract obstruction or renal stone disease
- Additional investigations, such as a contrast-enhanced computed tomography scan, or excretory urography, if the patient remains febrile after 72 h of treatment, or immediately if there is a deterioration in clinical status 1.
From the Research
Signs and Symptoms of Pyelonephritis
- Fever (temperature ≥ 38.5° C) 2
- Flank pain (typically unilateral) 2, 3
- Nausea and vomiting 2
- Costovertebral angle tenderness 2
- Complaints typical of lower UTI may be variably present 2
- Severity of symptoms can range from a mild pyrexial illness to life-threatening sepsis 2
Diagnosis and Laboratory Tests
- Urine dipstick test for nitrites and leukocyte esterase may be negative in some cases, but this does not exclude the diagnosis 2
- Urine culture with antimicrobial susceptibility testing should be performed in all patients 3
- Blood cultures and measurement of serum inflammatory markers are not necessary in uncomplicated cases 3
- Imaging studies are not necessary in uncomplicated cases, but may be necessary in cases of treatment failure or concurrent urinary tract obstruction 3
Treatment and Management
- Antibiotic therapy should be initiated without delay, and can be modified subsequently depending on the culture result 2
- Fluoroquinolones and trimethoprim/sulfamethoxazole are effective oral antibiotics in most cases, but increasing resistance makes empiric use problematic 3
- Parenteral antibiotic therapy is recommended for patients admitted to the hospital, and those with sepsis or risk of infection with a multidrug-resistant organism 3
- Most patients respond to appropriate management within 48 to 72 hours, and those who do not should be evaluated with imaging and repeat cultures while alternative diagnoses are considered 3