Overview
Acute pyelonephritis is a sudden and severe kidney infection usually caused by bacteria that ascend from the lower urinary tract. It can affect one or both kidneys and requires prompt antibiotic treatment to prevent serious complications.
If left untreated, the infection can spread to the bloodstream and become life-threatening. Early diagnosis and appropriate therapy are essential for recovery.
Symptoms
- High fever (often above 101°F) with chills and rigors
- Flank or lower back pain on one or both sides
- Painful, burning, or frequent urination
- Nausea, vomiting, and loss of appetite
- Cloudy, dark, or foul-smelling urine
- Blood in the urine (hematuria)
- Generalized weakness and malaise
- In elderly patients, confusion may be the only symptom
Causes
- Bacterial infection: Most commonly Escherichia coli (E. coli), but also Klebsiella, Proteus, and Enterococcus.
- Urinary tract obstruction: Kidney stones, enlarged prostate, or tumors that block urine flow.
- Vesicoureteral reflux: Urine flows backward from the bladder to the kidneys.
- Catheter use: Indwelling urinary catheters increase infection risk.
- Weakened immune system: Diabetes, HIV, or immunosuppressive therapy.
- Pregnancy: Hormonal and anatomical changes increase risk.
Treatment
- Antibiotics: Oral or intravenous (IV) depending on severity. Typical duration is 7–14 days.
- Fluids: Increased hydration helps flush bacteria from the urinary tract.
- Pain management: Analgesics for flank pain and fever.
- Hospitalization: Required for severe cases, dehydration, or if oral antibiotics are not tolerated.
- Surgery: Rarely needed, but may be necessary to remove obstructions or drain abscesses.
- Treat underlying causes: Address kidney stones, structural abnormalities, or reflux.