Kidney infection

A kidney infection (pyelonephritis) is a bacterial infection of one or both kidneys, usually spreading upwards from an infection of the bladder or lower urinary tract. It's more serious than a bladder infection and needs prompt treatment to prevent kidney damage or bloodstream spread.

Symptoms

• Pain in the back, side, or groin (sometimes severe)
• Fever and chills / rigors
• Nausea or vomiting
• Feeling generally very unwell
• Burning or pain while passing urine
• Needing to pass urine often, with urgency
• Cloudy, dark, or strong-smelling urine; sometimes blood
• In older adults, symptoms can be less obvious — confusion, reduced appetite, generally "off"

Kidney infection can be serious — go to a doctor urgently, and to hospital if you have high fever with rigors, severe pain, vomiting, confusion, or signs of sepsis.

Who is at higher risk?

• Women — shorter urethra makes UTIs more common
• Pregnancy
• Urinary tract abnormalities — kidney stones, enlarged prostate, anatomical variations
• Urinary catheter use
• Diabetes
• Conditions that suppress the immune system
• Recurrent bladder infections

Diagnosis

• Urine test (microscopy and culture) — identifies the bacterium and its antibiotic sensitivity
• Blood tests — check kidney function, signs of bloodstream infection
• Ultrasound or CT — if there are complications, stones, or recurrent infections

Treatment

• Antibiotics — typically for 7-14 days. Mild cases can be treated with oral antibiotics at home; severe cases need intravenous antibiotics in hospital
• Pain relief — paracetamol and, if needed, other pain medicines
• Fluids — keep well hydrated
• Follow-up to confirm clearance, especially in pregnancy

Empirical antibiotic choice depends on local resistance patterns — antibiotic resistance in urinary pathogens is high in many Indian hospitals. Cultures matter.

Prevention

• Drink plenty of water
• Don't hold urine for long
• Pass urine soon after sex
• Women: wipe from front to back after using the toilet
• Treat lower urinary tract infections promptly
• Manage diabetes well
• Pregnancy: routine urine checks at antenatal visits catch asymptomatic UTIs that can progress to kidney infection