Duration of Antibiotics in Intra Abdominal Infection

• The appropriate duration of therapy remains unclear.
• Traditionally, practitioners have treated patients until all evidence of SIRS has resolved, typically for 7 to 14 days.
• They reasoned that ongoing sepsis was indicative of ongoing replication of pathogens. More recent experimental data, however, suggest that a prolonged SIRS may be more a reflection of host immune activity than an indication of the presence of viable microorganisms
• More recently, it has been suggested that with adequate source control, a shorter course of 3 to 5 days should suffice for cure and could decrease the risk of antimicrobial resistance.

Recommendations

• Antimicrobial therapy of established infection should be limited to 4–7 days, unless it is difficult to achieve adequate source control. 
• Longer durations of therapy have not been associated with improved outcome
• resolution of clinical signs of infection should be used to judge the termination point for antimicrobial therapy. 
• The risk of subsequent treatment failure appears to be quite low in patients who have no clinical evidence of infection at the time of cessation of antimicrobial therapy
• This usually implies that the patients are afebrile, have normal white blood cell counts, and are tolerating an oral diet

Evidences:

• A prospective, randomized, double-blind trial comparing 3- and ≥ 5-day ertapenem regimens in 111 patients with community-acquired intra-abdominal infections reported similar cure and eradication rates (93% vs. 90% and 95% vs. 94% for 3- and > 5-day regimens, respectively)
• Intra-abdominal sepsis patients at risk for post-operative infection were those who were afebrile with persistent leukocytosis or those who remained febrile after the antibiotics were discontinued.
• In the study, 929 patients with intraabdominal infections associated with fever or leukocytosis were categorized into quartiles on the basis of either the total duration of antibiotic therapy or the duration of treatment following resolution of fever and leukocytosis. Shorter courses of antibiotics were associated with comparable or fewer complications than prolonged therapy.

Longer Durations:

• Despite these recommendations, observational studies show that therapy is typically administered for 10 to 14 days.
•  One reason that shortening therapy has been difficult is the 20% rate of clinically significant infectious complications after treatment.
• These subsequent complications, however, are often due to progression of the original disease or inadequate original source control and may not be preventable with antimicrobial therapy alone

References:

1. http://www.nejm.org/doi/full/10.1056/NEJMoa1411162?rss=mostViewed&#t=articleBackground
2. 2013 WSES guidelines for management of intra-abdominal infections
3. Diagnosis and Management of Complicated Intra-abdominal Infection in Adults and Children: Guidelines by the Surgical Infection Society and the Infectious Diseases Society of America (2011)