NEW YORK (Reuters Health) – Clinicians can safely observe patients with a first episode of uncomplicated diverticulitis and omit the routine use of antibiotics, researchers in the Netherlands report.

“Colonic diverticular disease is a common condition in Western society which has an increasing incidence and imposes a high socioeconomic burden,” Dr. Lidewine Daniels of the University of Amsterdam told Reuters Health.

“Until recently, it was uncertain whether antibiotics are necessary in the treatment of a first episode of uncomplicated acute diverticulitis and to date, use of antibiotics is advised in most guidelines,” he said by email.

He added, “Omitting antibiotics could be a more cost-effective treatment and importantly, is in line with the World Health Organization’s strategy to combat worldwide escalating antimicrobial resistance by reducing antibiotic overuse.”

To investigate, Dr. Daniels and colleagues recruited patients with a first episode of left-sided, mild acute diverticulitis with a diagnosis confirmed by ultrasound or computed tomography to the DIABOLO (Diverticulitis: AntiBiotics Or cLose Observation?) trial. They analyzed data for 262 patients randomized to observation and 266 to antibiotics.

The antibiotic regimen consisted of a 10-day course of amoxicillin-clavulanic acid, with intravenous administration of 1200 mg four times daily for at least 48 hours, after which patients could switch to 625 mg pills three times daily.

As reported in the British Journal of Surgery, patients in the observation group recovered within an average of two weeks, whereas the antibiotic group recovered within an average of 12 days (hazard ratio for recovery, 0.91).

There were no significant differences between the groups for secondary endpoints, including complicated diverticulitis (3.8% versus 2.6 %, respectively), ongoing diverticulitis (7.3% versus 4.1%), recurrent diverticulitis (3.4% versus 3.0%), sigmoid resection (3.8% versus 2.3%), readmission (17.6% versus 12.0%), adverse events (48.5% versus 54.5%) and mortality (1.1% versus 0.4%).

In addition, the hospital stay was significantly shorter in the observation group (two days compared with three days for the antibiotic group).

Dr. Daniels said, “This trial shows observational treatment is without significant repercussions, which indicates that antibiotics can safely be omitted. The outcomes confirm the results of a 2012 Scandinavian trial, which also investigated the need for antibiotic treatment in acute uncomplicated diverticulitis.

“There now is sufficient evidence for omitting the routine administration of antibiotics in patients with uncomplicated diverticulitis,” he concluded.

Dr. David Greenwald, director of clinical gastroenterology and endoscopy at The Mount Sinai Hospital in New York City, told Reuters Health, “Acute diverticulitis generally is mild and resolves on its own. Patients typically are treated with a period of bowel rest, and often are given antibiotics. Since uncomplicated diverticulitis is not felt to have an infectious etiology, it has never been clear that antibiotics were helpful, but nonetheless, they have become a common part of treatment.”

“The clinical implications of not using antibiotics for an initial episode of uncomplicated diverticulitis are many, and include potentially decreased costs, and a lower risk of the development of antibiotic resistance worldwide,” he said by email.

“Moreover, not using antibiotics routinely for a first episode of uncomplicated diverticulitis would lead to a very important reduction in the incidence of antibiotic-associated diarrhea and Clostridium difficile-associated illnesses,” he noted. “These outcomes would have a major clinical impact.”

Dr. Eamonn Quigley, chief of gastroenterology and hepatology at Houston Methodist Hospital in Texas, observed, “This is one of a number of recent studies that have questioned several of the traditional approaches to the management of diverticulitis.”

“This study now questions one of the remaining pillars of the traditional approach: the fundamental role of antibiotics,” he told Reuters Health by email.

“Their results suggest that antibiotics can be avoided among those with uncomplicated diverticulitis,” he said, emphasizing that “high-quality imaging was essential in making the initial diagnosis,” and both high-risk patients and those who had prior episodes of diverticulitis were excluded.

Dr. Quigley concluded, “These results will be welcomed as a further contribution to reducing antibiotic exposure in the general population.”