Slow Thinking for Fast Results: Reclaiming Analytical Reasoning in Antimicrobial Susceptibility Test Interpretation

Antimicrobial susceptibility testing (AST) is the basis of directed antimicrobial therapy and stewardship. However, its interpretation frequently relies on rapid and intuitive judgment, rather than on deliberate analytical reasoning. Using Kahneman's dual-process theory of cognition, we argue that AST interpretation is particularly vulnerable to system 1 heuristic bias, especially in real clinical environments. Using illustrative examples from contemporary resistance scenarios, such as extended-spectrum β-lactamase-producing Enterobacterales and multidrug-resistant Pseudomonas aeruginosa, we discuss the evolving resistance patterns over years, and it has increased interpretive complexity beyond what categorical AST outputs alone convey. We propose that interpretative errors may often arise from predictable cognitive responses, rather than from insufficient knowledge, which may be reinforced by current laboratory reporting formats and clinical workflows. Finally, we discuss educational, structural, and reporting strategies to foster system 2 engagement and mechanism-aware interpretation, with implications for antimicrobial stewardship and the training of medical students and early-career clinicians.