What is the recommended antibiotic treatment for colitis caused by bacterial infections, such as Clostridioides difficile (C. diff)?

Antibiotic Treatment for Clostridioides difficile Colitis

For non-severe C. difficile infection (CDI), oral metronidazole 500 mg three times daily for 10 days is the first-line treatment, while severe CDI should be treated with oral vancomycin 125 mg four times daily for 10 days. 1

Classification of CDI Severity

Non-severe CDI

• Stool frequency < 4 times daily
• No signs of severe colitis
• No marked leukocytosis (WBC < 15 × 10⁹/L)
• Normal serum albumin (≥ 30 g/L)
• Normal serum creatinine

Severe CDI (any of the following)

• Marked leukocytosis (WBC > 15 × 10⁹/L)
• Decreased serum albumin (< 30 g/L)
• Rise in serum creatinine (≥ 133 μM or ≥ 1.5 times baseline)
• Signs of severe colitis (fever, abdominal pain, ileus)
• Pseudomembranous colitis on endoscopy

Treatment Algorithm

Initial Episode or First Recurrence

1. Non-severe CDI:

   • First choice: Metronidazole 500 mg orally three times daily for 10 days (A-I) 1
   • In mild cases clearly induced by antibiotics, consider stopping the inducing antibiotic and observing for 48 hours with close monitoring (C-II) 1

2. Severe CDI:

   • First choice: Vancomycin 125 mg orally four times daily for 10 days (A-I) 1, 2
   • The use of metronidazole in severe CDI is strongly discouraged (D-I) 1

3. When oral therapy is not possible:

   • Non-severe: Intravenous metronidazole 500 mg three times daily for 10 days (A-III) 1
   • Severe: Intravenous metronidazole 500 mg three times daily for 10 days PLUS vancomycin 500 mg in 100 mL normal saline as retention enema every 4-12 hours (A-II) and/or vancomycin 500 mg four times daily by nasogastric tube (A-II) 1

Multiple Recurrences (≥2)

1. First choice:

   • Fidaxomicin 200 mg orally twice daily for 10 days (B-II) 1
   • OR Vancomycin 125 mg orally four times daily for 10 days followed by either:
     • Pulse strategy: 125-500 mg/day every 2-3 days for at least 3 weeks (B-II) 1
     • Taper strategy: gradually decreasing the dose to 125 mg per day (B-II) 1

2. When oral therapy is not possible:

   • Intravenous metronidazole 500 mg three times daily for 10-14 days PLUS vancomycin retention enema 500 mg in 100 mL normal saline every 4-12 hours (C-III) and/or vancomycin 500 mg four times daily by nasogastric tube (C-III) 1

Important Clinical Considerations

• Vancomycin is more effective than metronidazole for severe CDI but should be reserved for severe cases to prevent development of vancomycin-resistant organisms 3
• Lower dose vancomycin (125 mg four times daily) is as effective as higher dose (500 mg four times daily) and is more cost-effective 4
• Clinical response typically occurs within 2-4 days of starting treatment 5, 4
• Approximately 20% of patients may experience recurrence after initial treatment 5, 3, 4
• Antiperistaltic agents and opiates should be avoided as they may mask symptoms and potentially worsen the disease (B-II) 1

Surgical Considerations

Colectomy should be considered in:

• Perforation of the colon
• Systemic inflammation and deteriorating clinical condition not responding to antibiotic therapy
• Toxic megacolon or severe ileus
• Surgery should be performed before colitis becomes very severe (serum lactate < 5.0 mmol/L) 1

Emerging Treatments

For multiple recurrent CDI unresponsive to repeated antibiotic treatment, fecal microbiota transplantation in combination with oral antibiotic treatment is strongly recommended (A-I) 1, 6

Monitoring

• Monitor stool frequency and consistency
• Follow leukocyte count, serum albumin, and creatinine levels
• In patients >65 years, monitor renal function during and after treatment with vancomycin to detect potential nephrotoxicity 2
• Treatment response is defined as decreased stool frequency or improved stool consistency after 3 days with no new signs of severe colitis 1

Remember that C. difficile may continue to be present in stool after clinical symptoms resolve, and testing for cure is not recommended.