In outpatient management of diverticulitis, which antibiotic regimen is preferred?

• A. Amoxicillin alone
• B. Fluoroquinolone with metronidazole
• C. Piperacillin-tazobactam
• D. Ceftriaxone plus azithromycin

Answer: (B)

The key idea is choosing an antibiotic plan that reliably covers the bacteria commonly causing diverticulitis while staying suitable for outpatient, oral treatment. Diverticulitis involves infection of colonic diverticula, so you want coverage for both aerobic gram-negative bacteria (like E. coli) and anaerobes (like Bacteroides). A regimen that combines a fluoroquinolone with metronidazole fits this need well: the fluoroquinolone provides strong activity against gram-negative enteric organisms, and metronidazole adds robust anaerobic coverage. Together, they offer effective, convenient oral therapy that can be used outside the hospital.

Amoxicillin alone wouldn’t adequately cover anaerobes, limiting its effectiveness in diverticulitis. Piperacillin-tazobactam is a broad-spectrum agent typically given IV and is reserved for more severe or inpatient cases. Ceftriaxone plus azithromycin also isn’t ideal for diverticulitis because azithromycin has limited anaerobic coverage and this combination is not the standard choice for colonic infections, plus it often implies IV therapy. Therefore, the combination of a fluoroquinolone and metronidazole best meets the needs of outpatient management by providing comprehensive coverage with oral agents.