ContextThe use of explicit definitions of potentially inappropriate prescriptions of antibiotics (antibiotic PIPs) might constitute an innovative means to fight against antimicrobial resistance. Explicit definitions of PIPs can reduce the rate of inappropriate prescriptions, but explicit definitions of antibiotic PIPs in geriatric medicine are currently lacking. The objective of the study was to develop explicit definitions of antibiotic PIPs for hospitalized older patients.MethodWe performed a qualitative study of focus groups involving geriatricians and infectious disease specialists. The study complied with the Consolidated Criteria for Reporting Qualitative Research. Transcripts of audio recordings were analyzed in a two-step independent reviewing process. The exact wording of the definitions was validated by a steering committee, an independent expert group, and the focus group participants.ResultsThe four focus groups comprised 28 stakeholders. Our analysis identified 65 explicit definitions of antibiotic PIPs: 47 (73%) concerned misuse, 15 (23%) concerned overuse and three (5%) concerned underuse. Most definitions were related to critically important antibiotics: 11 (17%) for fluoroquinolones, eight (12%) for amoxicillin-clavulanic acid, eight (12%) for cephalosporins, seven (11%) for aminoglycosides, and five (8%) for carbapenems.ConclusionTo address the public health challenge of antimicrobial resistance, our study generated explicit definitions for antibiotic PIPs in older patients. We intend to refine and to validate these definitions through a national Delphi survey; the resulting consensus might provide key messages for prescribers and open up perspectives for reducing the incidence of antibiotic PIPs.