Treatment of Infectious Terminal Ileitis
For infectious terminal ileitis, initiate empiric antibiotic therapy with ceftriaxone 1-2g IV daily PLUS metronidazole 500mg IV every 8 hours, or alternatively piperacillin-tazobactam 3.375-4.5g IV every 6-8 hours as a single agent, for a duration of 3-5 days after clinical improvement. 1, 2, 3
Empiric Antibiotic Selection
The choice of empiric antibiotics must cover gram-negative bacteria and anaerobes, which are the predominant organisms in the terminal ileum and colon. 1, 2
First-Line Regimens:
Piperacillin-tazobactam 3.375-4.5g IV every 6-8 hours provides comprehensive single-agent coverage of gram-negatives, anaerobes, and gram-positive organisms 1, 2, 3
Ceftriaxone 1-2g IV daily PLUS metronidazole 500mg IV every 8 hours is an equally effective combination regimen 1, 2, 4
Cefotaxime 2g IV every 8 hours PLUS metronidazole 500mg IV every 6-8 hours serves as another alternative combination 1
Special Circumstances:
For patients with beta-lactam allergy: Use ciprofloxacin 400mg IV every 8-12 hours PLUS metronidazole 500mg IV every 6-8 hours 1, 2
For critically ill or septic patients: Consider meropenem 1g IV every 8 hours, imipenem/cilastatin 1g IV every 8 hours, or ertapenem 1g IV every 24 hours 1, 2
For suspected Campylobacter in travelers or areas with quinolone resistance: Azithromycin 500mg daily for 3 days is superior to fluoroquinolones 5
Critical Pitfalls to Avoid
Never omit anaerobic coverage when treating terminal ileitis, as anaerobes are essential pathogens in this location. 1, 3
Avoid ampicillin-sulbactam due to high resistance rates among community-acquired E. coli. 3
Avoid fluoroquinolone monotherapy in areas with quinolone-resistant E. coli or when Campylobacter is suspected. 3, 5
Duration of Therapy
A short course of 3-5 days is recommended for patients showing adequate clinical response with resolution of fever, abdominal pain, and diarrhea. 1, 2, 3
- For immunocompetent, stable patients: minimum 4 days 1
- For immunocompromised or critically ill patients: up to 7 days based on clinical response 1
Monitoring and Clinical Response
Monitor the following parameters to assess treatment response:
- Clinical signs: Resolution of abdominal pain, fever, and diarrhea 1
- Laboratory markers: White blood cell count, C-reactive protein, procalcitonin, and lactate 1
- Stool frequency and character on days 0,1,2,3, and follow-up 6, 5
If signs of ongoing infection persist beyond 5-7 days, obtain repeat imaging (CT scan) to exclude abscess formation or complications requiring surgical intervention. 1
Transition to Oral Therapy
Once the patient is clinically improving, afebrile for 24-48 hours, and tolerating oral intake:
- Amoxicillin-clavulanate 875/125mg orally twice daily 1
- Ciprofloxacin 500mg orally twice daily PLUS metronidazole 500mg orally three times daily 1
Diagnostic Considerations
While initiating empiric therapy, obtain stool cultures to identify specific pathogens:
- Yersinia species is the most frequently detected organism in acute infectious ileitis (33.3% of cases) 6
- Campylobacter species is common in travelers and may require azithromycin if quinolone resistance is prevalent 6, 5
- Other infectious causes include Salmonella, Shigella, and anaerobic bacteria 7, 4, 8
De-escalate antibiotic therapy based on culture results to prevent resistance development. 2
Important Clinical Context
Terminal ileitis has multiple etiologies beyond infection, including Crohn's disease (12.1% of cases), NSAID-induced inflammation, lymphoid hyperplasia, and gynecologic conditions (9.1% of cases, particularly in women). 7, 8, 6 However, when infectious ileitis is confirmed or strongly suspected based on acute presentation with fever, diarrhea, and imaging showing terminal ileal inflammation, empiric antibiotic therapy as outlined above is appropriate. 6
Consider local antibiotic resistance patterns when selecting empiric therapy, as resistance rates vary geographically. 9, 2