STOP-IT Trial: Fixed-Duration Antibiotic Therapy for Intraabdominal Infections [Classics Series]

1. The STOP-IT trial found that 4 days of fixed antibiotic therapy after surgical or percutaneous source control is as effective as a longer, symptom-guided course for patients with complicated intraabdominal infections.

2. These findings support antibiotic stewardship, reducing unnecessary antibiotic exposure without compromising patient safety.

Evidence Rating Level: 1 (Excellent)      

Find more landmark study summaries like this in the book 2 Minute Medicine’s The Classics in Medicine: Summaries of the Landmark Trials, 2e (The Classics Series).

Study Rundown: The STOP-IT trial (Strategies to Optimize the Duration of Prophylaxis in Intraabdominal Infection Therapy) was a landmark randomized controlled trial that challenged the longstanding practice of tailoring antibiotic duration to clinical resolution of fever, leukocytosis, and ileus.

Traditionally, clinicians often extended antibiotic therapy for 7–10 days or longer until overt signs of infection resolved. This approach, however, contributes to antimicrobial resistance, adverse events, and higher healthcare costs. The STOP-IT trial instead tested whether a short, fixed course of 4 days would provide equivalent protection against post-surgical infectious complications.

Among 518 adults with complicated intraabdominal infections who achieved adequate source control, the trial found no difference in the rate of surgical site infections, recurrent intraabdominal infections, or death between the fixed-duration and symptom-guided groups.

Click to read the study, published today in NEJM

Relevant Reading: Comparison of 8 vs 15 days of antibiotic therapy for ventilator-associated pneumonia in adults: a randomized trial

In-Depth [randomized controlled trial]:  The STOP-IT trial was a multicenter, open-label randomized controlled trial conducted across 23 hospitals in the United States between 2008 and 2013. Eligible participants were adults with complicated intraabdominal infections who had undergone successful surgical or percutaneous source control. Patients with inadequate source control, severe immunocompromise, or uncontrolled sepsis were excluded to ensure safety and generalizability.

Study Design and Interventions

A total of 518 patients were randomized into two groups:

1. Fixed-duration group: Received antibiotics for exactly 4 calendar days after source control, regardless of symptoms.

2. Control group (traditional therapy): Continued antibiotics until at least 2 days after clinical signs of infection resolved — specifically, fever, elevated white blood cell count, or ileus. The median duration in this group was 8 days (IQR 5–10 days).

All patients received standard broad-spectrum antibiotic therapy, chosen at the discretion of treating physicians, consistent with IDSA guidelines at the time.

Outcomes and Results

The primary endpoint was a composite outcome of surgical site infection, recurrent intraabdominal infection, or death within 30 days of source control.

• In the fixed-duration group, 21.8% of patients experienced the composite outcome.

• In the traditional group, 22.3% of patients experienced the same outcome.

• This difference was not statistically significant, demonstrating non-inferiority of the shorter course.

Secondary outcomes, including length of hospital stay, incidence of Clostridioides difficile infection, and rates of other healthcare-associated infections, were also similar between the two groups. Importantly, there was no evidence of harm from limiting antibiotic therapy to just 4 days.

Clinical Implications

The STOP-IT trial directly addressed a long-standing clinical debate: whether the duration of antibiotics for intraabdominal infections should be determined by patient recovery or by a fixed evidence-based protocol. The results provide strong evidence that longer is not necessarily better when it comes to antibiotic therapy.

By demonstrating that short-course therapy is equally effective, the STOP-IT trial supports modern antimicrobial stewardship strategies. Limiting unnecessary antibiotic exposure can:

• Reduce the risk of antibiotic resistance

• Decrease the risk of antibiotic-associated complications such as C. difficile colitis

• Lower healthcare costs and shorten hospital stays

The trial has been widely cited in updated IDSA and Surgical Infection Society guidelines, which now endorse shorter, fixed-duration antibiotic courses following adequate source control.

STOP-IT Trial Summary Table

Image: PD

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