Microbiology & risk factors
Organisms
- E. coli — 75–90%
- Klebsiella, Proteus, Enterobacter — 5–10%
- Pseudomonas, Enterococcus — catheterised/healthcare
- Staph saprophyticus — young sexually active women
- Candida — diabetic, prolonged antibiotics, immunocompromised
Risk Factors
- Female sex (short urethra)
- Pregnancy (ureteric dilation, urinary stasis)
- Diabetes mellitus
- Renal tract obstruction (stones, BPH, stricture)
- Vesicoureteric reflux (children)
- Indwelling catheter
- Recent urinary tract instrumentation
- Immunosuppression
- Polycystic kidney disease (cyst infection)
Clinical features & investigation
Symptoms
- Loin / flank pain (often unilateral)
- Fever ± rigors
- Lower UTI symptoms: dysuria, frequency, urgency
- Nausea, vomiting, malaise
- Confusion in elderly
Signs
- Pyrexia, tachycardia
- Costovertebral angle tenderness
- Loin tenderness on palpation
- Hypotension if septic shock
Investigations
- Urinalysis (dip): leucs +, nitrites +, blood ±
- MSU for culture & sensitivity BEFORE antibiotics
- FBC, U&E, CRP, glucose, blood cultures (if febrile or unwell)
- Pregnancy test in women of reproductive age
- Lactate if signs of sepsis
- CT urogram (or ultrasound) if:
– no improvement at 48–72 h – recurrent pyelonephritis (> 1 episode in 6 months) – stone or obstruction suspected – diabetes / immunocompromised – male patient (always urological referral)
Kidney Vitality is a daily multivitamin developed by a UK Consultant Nephrologist using renal nutrition principles. It contains no added potassium, magnesium, phosphorus or iron, and no herbal blends. See the formulation.
Treatment (NICE NG109)
OUTPATIENT (non-severe, non-pregnant, oral fluids tolerated):
- 1st line: CEFALEXIN 500 mg BD-TDS for 7–10 days
- Alternative: CO-AMOXICLAV 500/125 mg TDS for 7–10 days (if culture-susceptible)
- Alternative: TRIMETHOPRIM 200 mg BD for 14 days (if culture-susceptible)
- Alternative: CIPROFLOXACIN 500 mg BD for 7 days (MHRA warnings — tendinopathy, aortic aneurysm; reserve for when other options unsuitable)
INPATIENT (severe/septic):
- Sepsis Six within 1 hour
- IV CO-AMOXICLAV 1.2 g TDS ± gentamicin
- Or CEFTRIAXONE 1–2 g OD ± gentamicin
- Or AMIKACIN if recurrent / known resistance / penicillin-allergy
- Step down to oral when afebrile 24–48 h, guided by sensitivities
- Total 10–14 days
Pregnancy
- Always admit (especially T2/T3)
- 1st line: CEFALEXIN 500 mg BD-TDS for 7–10 days
- IV ceftriaxone if severe
- Avoid trimethoprim T1 (folate antagonist)
- Avoid nitrofurantoin T3 (risk of neonatal haemolysis)
- Avoid ciprofloxacin (cartilage)
Obstructed Infected Kidney
- UROLOGICAL EMERGENCY
- Urgent ureteric stent or nephrostomy decompression
- IV antibiotics, sepsis management
- Definitive stone management AFTER infection cleared
Complications & prevention
Complications
- Sepsis / septic shock
- Renal or perinephric abscess (often Staph aureus or persistent E. coli)
- Emphysematous pyelonephritis — gas-forming infection, almost exclusively in diabetics, mortality 20–40%; CT diagnostic; urgent drainage ± nephrectomy
- Acute kidney injury
- Pyonephrosis (pus in obstructed system)
- Papillary necrosis (especially diabetics, sickle cell, analgesic use)
- Xanthogranulomatous pyelonephritis (chronic, often associated with staghorn stone; nephrectomy usually required)
- In pregnancy: pre-term labour, low birth weight
PREVENTION (recurrent):
- Treat underlying anatomical cause (stones, BPH, stricture)
- Adequate hydration (1.5–2 L daily)
- Post-coital voiding; cranberry products (modest evidence)
- D-mannose 2 g/day — emerging evidence in recurrent E. coli UTI
- Vaginal oestrogen in post-menopausal women
- Methenamine hippurate 1 g BD — non-antibiotic prophylaxis (ALTAR trial)
- Low-dose antibiotic prophylaxis (trimethoprim 100 mg nocte, nitrofurantoin 50–100 mg nocte) — only if recurrent and other measures insufficient
