Which antibiotic most increases the risk of pseudomembranous colitis (Clostridioides difficile infection)?

Clindamycin is classically associated with the highest relative risk of C. difficile-associated pseudomembranous colitis due to marked disruption of normal colonic flora.Other options: Penicillin, tetracycline, and amoxicillin can contribute but carry lower classic association than clindamycin (though broad-spectrum agents such as fluoroquinolones and cephalosporins are also high-risk).Key exam takeaway: Clindamycin is the classic exam answer for antibiotic-associated pseudomembranous colitis.