Antibiotics were routinely prescribed in almost 97% of outpatient visits for uncomplicated diverticulitis — more than 10 years after the American Gastroenterological Association (AGA) guideline called for selective use in 2015, a retrospective cohort study in US veterans found.

Publishing a short report in Annals of Internal Medicine, infectious disease pharmacist Jesse D. Sutton, PharmD, MS, and colleagues at the Minneapolis Veterans Affairs (VA) Health Care System in Minneapolis, called for interventions to align prescribing practices with current guidelines and reduce the harms of unnecessary antibiotic exposure.

In a 2020 update, the AGA supported selective antibiotic treatment in immunocompetent patients with mild acute uncomplicated diverticulitis. The American College of Physicians made a recommendation against routine antibiotic prescribing in 2022.

Other researchers have highlighted the problem as well, pointing out the noninferiority of no antibiotic treatment for uncomplicated disease.

Uncomplicated diverticulitis likely has not yet been a focus for antimicrobial stewardship interventions because it is far less frequent than other scenarios where antibiotics are prescribed, such as acute respiratory infections, asymptomatic bacteriuria, and urinary tract infections, said Sutton in an interview with Medscape Medical News. “We viewed uncomplicated diverticulitis as a meaningful opportunity for antimicrobial stewardship intervention because the current shift is from historically prescribing antibiotics to no antibiotics.”

National Cohort Study

Conducted across 120 VA facilities, the study spanned the period from October 2015 to June 2025, tracking 33,634 visits made by 28,474 unique patients. The overall age in the cohort was about 63 years, 90% of patients were men, and three quarters were White. The median BMI was 30.

Of these visits, 32,497 resulted in an antibiotic prescription, whereas just 1137 yielded no prescription. The adjusted prevalence of visits with a prescription remained between 95.6% (95% CI, 94.6%-96.0%) and 97.9% (CI, 97.4%-98.4%) for all years from 2015 to 2025. For the 116 VA facilities with 30 or more visits during that time, the median unadjusted prevalence of visits with an antibiotic prescribed was 97%.

“The surprising aspect was how consistently antibiotics were prescribed across time, different VA facilities, and all patient stratifications such as age, comorbidities, and presence of systemic signs,” Sutton said.

A fluoroquinolone-based regimen (n = 15,330; 45.6%) and amoxicillin-clavulanate (n = 14,369; 42.7%) were the most common prescriptions in 2015, but the predominant type shifted from fluoroquinolone in 2015 to amoxicillin-clavulanate in 2025.“Fluoroquinolones-based regimens were prescribed in about 80% of visits in 2015-2016 but about 25% of visits in 2024-2025,” he said.

In a subanalysis, antibiotics were prescribed in 10 of 50 visits (20%) with no electronically captured antibiotic order, and in 50 of 50 visits (100%) with an electronic order.

Is this practice more common in VA facilities? “With regard to overall quality and safety of patient care, the studies I’m aware of typically suggest the quality and/or safety of care in the VA is as good as or better than non-VA sites of care,” Sutton said.

“Antibiotics are commonly given for uncomplicated diverticulitis — despite professional guidelines suggesting that antibiotic treatment is not generally required,” agreed Bruce E. Hirsch, MD, a geriatrics specialist in the Division of Infectious Diseases at Northwell Health’s North Shore University Hospital in Manhasset, New York, and not involved in the analysis.

But t he data demonstrating that antibiotics do not significantly improve diverticulitis outcomes — suggesting a more inflammatory than infectious cause — have yet to be clarified, he added. What is clear is that avoiding unnecessary antibiotics is important for reducing side effects, antibiotic resistance,

 Clostridioides difficile colitis risk, adverse impacts on the gut microbiome, and drug costs.

In the pressure of busy clinical practice, however, to recommend “bowel rest only” after a diagnosis of diverticulitis, especially given the risk for occasional septic complications, may seem inadequate to both parties, Hirsch said. “Education of provider and patient about the available data, the usually benign natural history, and the spectrum of deleterious impacts from unnecessary antibiotic use is needed.”

The authors acknowledged certain study limitations, including possible misclassification of uncomplicated diverticulitis owing to inaccurate diagnosis codes and reliance on electronic capture of antibiotic prescriptions. Manual validation identified underestimated antibiotic prescribing since some prescriptions were filled outside of the VA. Moreover, the findings reflect prescribing, but not necessarily patient exposure to antibiotics.

No direct funding support was involved in the conduct of this research or writing of the manuscript. This research was conducted through the use of resources and facilities at the Minneapolis VA Health Care System. The authors are employed by Minneapolis VA Health Care System. Sutton had no conflicts of interest. Co-author Dimitri M. Drekonja reported expert witness consulting and intellectual property related to reviewing chapters of a medical text.

Hirsch had no competing interests with regard to his comments.