Do kidney stones require antibiotics?

Management of Kidney Stones and Antibiotics

Kidney stones alone do not require antibiotics unless there is evidence of urinary tract infection or obstruction causing infection.

When Antibiotics Are Needed with Kidney Stones

Antibiotics are indicated in the following specific scenarios:

1. Infected stones (struvite/infection stones)

   • These are stones formed due to urease-producing bacteria
   • Complete stone removal plus appropriate antibiotic therapy is required 1

2. Obstructive pyelonephritis

   • Kidney stones causing urinary obstruction with infection is a urologic emergency
   • Requires immediate decompression (via PCN or ureteral stenting) and antibiotics 2
   • Untreated bacteriuria with urinary tract obstruction can lead to infectious complications and urosepsis 2

3. Prior to stone removal procedures

   • Urine culture is recommended before intervention
   • Appropriate antibiotic therapy should be administered before intervention if infection is suspected or proven 2

4. Secondary infection of existing stones

   • Non-infection stones can become secondarily infected and require antibiotics 1

Diagnostic Approach

• Obtain urine culture before starting antibiotics in suspected UTI with stones 3
• Screening with dipsticks might be sufficient in uncomplicated cases 2
• Blood cultures should be obtained if upper UTI or kidney cyst infection is suspected 2
• Imaging (ultrasound, CT) to assess for obstruction when infection is suspected 2

Antibiotic Selection When Indicated

When antibiotics are required for infected stones or obstructive pyelonephritis:

1. For uncomplicated UTI with stones:

   • First-line options: nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin (based on local resistance patterns) 3

2. For pyelonephritis with stones:

   • Oral options (if stable): Fluoroquinolones (ciprofloxacin 500-750mg BID or levofloxacin 750mg daily) for 7 days 2
   • IV options (if hospitalization required): Fluoroquinolones, aminoglycosides, extended-spectrum cephalosporins 2

3. For obstructive pyelonephritis (emergency):

   • Third-generation cephalosporins have shown superiority over fluoroquinolones 2
   • Broad-spectrum coverage until culture results available

Special Considerations

• History of kidney stones may predict increased resistance to nitrofurantoin (OR 3.24) 4
• Previous ureteroscopy is significantly associated with antibiotic resistance (OR 6.95) 5
• Duration of therapy for infection stones remains controversial:
  • Research shows no significant difference between 2-week versus 12-week antibiotic courses after percutaneous nephrolithotomy for infection stones 6

Management Algorithm

1. Assess for signs of infection:

   • Fever, chills, flank pain, leukocytosis, positive urinalysis
   • If absent → no antibiotics needed

2. If infection suspected:

   • Obtain urine culture
   • Assess for obstruction with imaging
   • Start empiric antibiotics based on local resistance patterns

3. If obstructive pyelonephritis present:

   • Emergency urinary decompression (PCN or ureteral stenting)
   • IV antibiotics (third-generation cephalosporins preferred)
   • Monitor for sepsis

4. For non-obstructive infection with stones:

   • Appropriate antibiotics based on culture
   • Consider complete stone removal to prevent recurrent infection

Common Pitfalls to Avoid

1. Treating asymptomatic bacteriuria without clinical signs of infection
2. Delaying decompression in obstructive pyelonephritis
3. Using fluoroquinolones as first-line when local resistance rates are high
4. Blind basketing for stone removal without endoscopic visualization 2
5. Inadequate follow-up for patients with infection stones who are at risk for recurrent infections

Remember that kidney stones themselves are not an indication for antibiotics unless there is evidence of infection. The primary goal is to treat any infection while addressing the underlying stone disease.