From the Guidelines
The best management for a patient with Crohn's disease on infliximab presenting with a perianal discharging fistula, induration, and low-grade fever for 3 weeks is to continue infliximab therapy, possibly with dose optimization, and to use a combination of surgical drainage, antibiotic therapy, and seton placement as needed. This approach is based on the most recent and highest quality evidence, including the 2024 ECCO guidelines on therapeutics in Crohn's disease, which recommend seton drainage preceding medical or surgical therapy for complex perianal CD fistulae 1. The initial management should include:
- Surgical drainage of any perianal abscess
- Antibiotic therapy with ciprofloxacin 500 mg twice daily and metronidazole 500 mg three times daily for 4-8 weeks
- Infliximab therapy should be continued, possibly with dose optimization to 10 mg/kg every 8 weeks if the current regimen is inadequate, as higher infliximab doses may be beneficial for perianal fistulising disease, with target levels >10 μg/mL associated with better response 1
- MRI of the pelvis should be obtained to assess fistula anatomy and exclude undrained collections
- Surgical placement of non-cutting setons may be necessary for complex or recurrent fistulas to facilitate drainage while preventing abscess formation The patient should be monitored closely for signs of systemic infection, as immunosuppression from infliximab increases infection risk. This approach addresses both the infectious component (antibiotics and drainage) and the underlying inflammatory disease (continued immunomodulatory therapy), which is essential because perianal fistulas in Crohn's disease result from transmural inflammation allowing enteric bacteria to form tracts through perianal tissues, requiring both infection control and inflammation management for optimal healing. The AGA clinical practice guidelines on the medical management of moderate to severe luminal and perianal fistulizing Crohn's disease also support the use of anti-TNFα agents, such as infliximab, for the induction and maintenance of remission in adult outpatients with moderate to severe CD 1.
From the FDA Drug Label
Fistulizing Crohn's Disease The safety and efficacy of infliximab were assessed in 2 randomized, double-blind, placebo-controlled studies in patients with fistulizing Crohn's disease with fistula(s) that were of at least 3 months duration. Concurrent use of stable doses of corticosteroids, 5-aminosalicylates, antibiotics, MTX, 6-mercaptopurine (6-MP) and/or azathioprine (AZA) was permitted In the first trial, 94 patients received 3 doses of either placebo or infliximab at Weeks 0,2 and 6. Fistula response (≥ 50% reduction in number of enterocutaneous fistulas draining upon gentle compression on at least 2 consecutive visits without an increase in medication or surgery for Crohn's disease) was seen in 68% (21/31) of patients in the 5 mg/kg infliximab group (P = 0. 002) and 56% (18/32) of patients in the 10 mg/kg infliximab group (P = 0.021) vs. 26% (8/31) of patients in the placebo arm.
The best management for a patient with Crohn's disease on infliximab presenting with a perianal discharging fistula, induration, and low-grade fever for 3 weeks is to use antibiotics before assessing the infliximab level, as the concurrent use of antibiotics is permitted in the treatment of fistulizing Crohn's disease.
- Key points:
- The patient is already on infliximab, which has shown efficacy in treating fistulizing Crohn's disease.
- The use of antibiotics is allowed in conjunction with infliximab.
- There is no direct information in the label to suggest increasing the dose of infliximab or using an MRI as the first step in management.
- The patient's symptoms, such as induration and low-grade fever, may indicate an infection that requires antibiotic treatment.
- Assessing the infliximab level after antibiotic treatment can help determine the next steps in management, such as adjusting the dose or continuing with the current treatment plan 2.
From the Research
Management of Perianal Discharging Fistula in Crohn's Disease
The patient presents with a perianal discharging fistula, induration, and low-grade fever for 3 weeks while on infliximab. The best management approach would involve:
- Assessing the need for antibiotics to manage the infection, considering the patient's symptoms and the potential for intra-abdominal infections 3, 4
- Evaluating the patient's response to infliximab and considering adjustments to their treatment regimen as needed
- Investigating the cause of the fistula and managing it appropriately, which may involve surgical intervention or other treatments
Role of Antibiotics
The use of antibiotics such as ciprofloxacin and metronidazole may be effective in managing intra-abdominal infections, including those associated with Crohn's disease 3, 4. However, the decision to start antibiotics should be based on a thorough assessment of the patient's condition and the potential risks and benefits of treatment 5, 6, 7.
Diagnostic Evaluation
A diagnostic evaluation, including imaging studies such as MRI, may be necessary to assess the extent of the fistula and guide treatment decisions. Additionally, a swab from the discharge may be helpful in identifying the causative organism and guiding antibiotic therapy.
Treatment Options
The treatment options for this patient include:
- Antibiotics to manage the infection, followed by an assessment of the patient's response to infliximab 3, 4
- Adjustment of the infliximab dose or switching to a different treatment regimen if necessary
- Surgical intervention to manage the fistula, if indicated
- MRI to evaluate the extent of the fistula and guide treatment decisions
The most appropriate initial step would be to start with antibiotics to manage the infection, as suggested by option B: Antibiotics then assess infliximab level 3, 4, 5, 6, 7.