BACKGROUND: The Centres for Antimicrobial Optimisation Network Brazil (CAMO-Net Brazil) aims to implement an antimicrobial stewardship program in a municipality with 165,000 inhabitants. This study explores barriers and enablers to its implementation, through understanding the context and beliefs regarding antimicrobial use in this environment. PROCEDURES: The study occurred in 12 primary healthcare units in São Paulo's metropolitan region, where a convergent parallel mixed-method study was conducted, i.e. quantitative and qualitative data were collected simultaneously, analyzed separately and its findings were then integrated in one unique discussion. A total of 208 out of 450 healthcare workers completed a Theoretical Domain Framework-based survey, and 16 patients and 12 health workers were interviewed. Survey results were compared by professional category
interviews were analyzed using Critical Discourse Analysis. FINDINGS: Professionals with higher education scored higher across most domains. In the "Optimism" domain, nurses, physicians, dentists, and pharmacists scored ≥6·0, while others scored ≤5·0. Similar patterns were observed in the domains "Knowledge" (≥6·0 vs ≤5·5), "Social/professional role and identity" (≥6·36 vs ≤5·79), and "Intentions" (≥6·0 vs ≤5·0). Qualitative data highlighted breaks in the continuity of care and gaps in patient and caregiver knowledge about antimicrobial use. Key barriers included disparities in training, physician-centered decision-making, and patient knowledge gaps. Enablers included healthcare workers' willingness to learn and home caregivers' understanding of patient conditions. Home caregivers emerged as key stakeholders in the implementation process. CONCLUSION: The implementation of the antimicrobial stewardship program depends on addressing training disparities and leveraging healthcare workers' willingness to learn.