Do You Know How Long to Use Antibiotics for Intraabdominal Infections?

Since 2010, there have been published guidelines for complicated intraabdominal infections which recommend a treatment course of 4 to 7 days. These include guidelines from the Surgical Infection Society (SIS) and the Infectious Diseases Society of America (IDSA). Now, a new study (Sawyer RG et al. NEJM 2015; 372: 1996-2005, editorial 2062-63) provides additional support for a short course of antibiotics when there is adequate source control. The study termed “Study to Optimize Peritoneal Infection Therapy” or STOP-IT included 23 institutions from the U.S. and Canada.

Video Summary (1:33): Trial of Short-Course Antimicrobials

Rationale: While traditional therapy of 10-14 days has been based on the premise that ongoing fever and leukocytosis indicate ongoing infection, “more recent experimental data, however, suggest that a prolonged SIRS [systemic inflammatory response syndrome] may be more a reflection of host immune activity than an indication of the presence of viable microorganisms.”

Design: 518 patients were randomly assigned to either a fixed 4-day course of antibiotics or to a control group that received antibiotics for 2 days after resolution of fever, leukocytosis, and ileus (max of 10 days).  The median number of days in the control group was 8 days.

Study characteristics:

  • Mean age 52 years
  • 34% of the infections originated in colon/rectum, 14% in small bowel, and 14% in the appendix
  • 11% had cancer, 10% had inflammatory bowel disease

Source-control procedures: “defined as procedures that eliminate infectious foci, control factors that promote ongoing infection, and correct or control anatomical derangements to restore normal physiological function”

  • Percutaneous drainage 33.1%
  • Resection and anastomosis or closure 26.5%
  • Surgical drainage alone 21.2%
  • Resection and proximal diversion 10.4%
  • Simple closure 7.7%
  • Surgical drainage and diversion 1.2%


  • Surgical site infection, recurrent intraabdominal infection, or death occurred in 21.8% of the experimental 4-day group compared with 22.3% of the control group. Death occurred in 3 experimental patients and 2 control patients.
  • No significant differences were found between the two groups in terms of primary or secondary outcomes.


  • 18% of the experimental group and 27% of the control group deviated from the protocol.  In the control group, this included 26 patients who received less than 10 days of therapy but more than 2 days longer than the resolution of the physiological findings.
  • Patients without adequate source control were excluded

The editorial notes that if these findings are incorporated into clinical practice, more than $97 million would be saved on antibiotic costs alone; in addition, there would be less diarrhea and phlebitis.  The editorial suggests that the reason why more than 20% of both groups had complications is likely related to source control.  If inadequate course of antibiotics was the culprit, “we would have expected still more complications after treatment in the short-course therapy group.”

(From editorial): “We have encouraging data from the STOP-IT trial that suggest cost savings and improved safety.”

Take-home message Because of years of practice patterns, it is going to be difficult to stop antibiotics at 4 days when patients are still having fevers, especially since 20% will not have resolution of their infection. These data should, however, make it easier to shorten antibiotic courses.

Related blog posts:

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