Antibiotic Treatment of Common Infections

More Evidence to Support Shorter Durations

Benjamin J. Smith; George Heriot; Kirsty Buising


Curr Opin Infect Dis. 2020;33(6):433-440. 

In This Article

Intraabdominal Infection

Complicated intraabdominal infections can be challenging to manage and, due to the high burden and polymicrobial nature of these infections, patients often receive prolonged courses of broad-spectrum antibiotics. However, for many of these infections, the existing randomized-trial evidence underscores the importance of definitive surgical management and the limited value of prolonging antibiotic exposure.

The Study to Optimize Peritoneal Infection Therapy trial concluded that four days of antibiotic therapy is noninferior to a prolonged course of 7–10 days in patients with intraabdominal infections with source control (surgical or percutaneous intervention to remove infectious foci).[30] There was no difference in rates of relapse or surgical site infection between the two arms, although these events occurred significantly later in the longer treatment group. Although rates of treatment failure were more than 20% in both groups, this study suggests that prolonging antibiotic therapy simply delays, rather than prevents, this outcome. A further French RCT has explored a similar question in a critically ill cohort of patients with intraabdominal infection.[31] Patients still requiring ICU support 8 days after definitive surgical management were randomized to either stop antibiotic therapy or continue for a further seven days with a primary outcome of antibiotic-free days at day 28. Patients in the short arm had significantly more antibiotic-free days (median 15 versus 12, P < 0.001) with no difference in most other clinical outcomes. The key exception was a higher rate of subsequent percutaneous drainage in the shorter treatment arm. As this was an unblinded study and, given equivalent rates of relapsed infection between the arms, this may reflect an increased clinician tendency for further intervention in patients who are no longer receiving antibiotics. Considered together, these two trials suggest that for patients with complicated intraabdominal infection who have adequate source control, there is unlikely to be any benefit in extending beyond four days of antibiotic therapy if stable and eight days if critically unwell.

Shorter durations of therapy may be possible where intraabdominal infection relates to appendicitis. For appendicitis associated with perforation or abscess (but not diffuse peritonitis), a small German RCT found that 24 h of antibiotic therapy may be sufficient.[32] For patients with uncomplicated acute appendicitis, there may be no meaningful role for antibiotics. A Korean RCT has compared conservative management of uncomplicated acute appendicitis (defined as an unperforated appendix with diameter between 6.1 and 11.0 mm on CT scan) with four days of antibiotic therapy compared with no antibiotic therapy and found no difference in initial treatment failure or clinical recurrence.[33] The overall treatment failure rates of around 20% in each arm suggest that surgery should still be considered the mainstay of therapy for most patients. However, for individuals with comorbidities associated with high intraoperative mortality, expectant management without antibiotic therapy may be a reasonable initial approach.

Many patients with uncomplicated diverticulitis will improve with expectant management. A randomized trial investigating observational versus antibiotic treatment for primary left-sided diverticulitis found no difference in time to recovery or rates of adverse outcomes.[34] Antibiotic therapy is generally recommended for patients with severe or complicated disease, underlying immunocompromise or failure to improve after 72 h. Total duration between 5 and 10 days is recommended depending on the adequacy of source control.[35]