Collateral Sensitivity Strongly Connected Components in Real-World Clinical Surveillance Data: Retrospective Detection of Evolutionary Traps in WHO Priority Pathogens

<jats:title>Abstract</jats:title> <jats:p> Collateral sensitivity (CS)—acquisition of resistance to one antibiotic inducing hyper-sensitivity to another — offers an evolutionary trap for multidrug-resistant pathogens. A <jats:italic>strongly connected component</jats:italic> (SCC) in the directed CS graph represents a closed cycle in which every drug is reachable from every other via successive CS edges. Prior evidence for CS SCCs derives exclusively from in vitro experiments; whether such structures exist in clinical surveillance data has not been tested. </jats:p> <jats:p> We mined 104,337 antibiotic susceptibility records from BV-BRC spanning four WHO critical-priority pathogens ( <jats:italic>Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa</jats:italic> ; 18,821 unique isolates). For each species, we applied Fisher’s exact test with Benjamini–Hochberg FDR correction to all ordered antibiotic pairs, detected SCCs via Tarjan’s algorithm, and assessed significance by permutation testing ( <jats:italic>n</jats:italic> = 1,000). </jats:p> <jats:p> Two species yielded qualifying SCCs. In <jats:italic>K. pneumoniae</jats:italic> (4,286 isolates), a 3-node SCC — imipenem, meropenem, tetracycline—was detected (empirical <jats:italic>p</jats:italic> = 0.001); both carbapenem– tetracycline edges are bidirectional (OR = 1.81–1.82, <jats:italic>q</jats:italic> &lt; 0.002, <jats:italic>n</jats:italic> &gt; 850 per edge). In <jats:italic>E. coli</jats:italic> (6,720 isolates), a bidirectional 2-node SCC links colistin and cefotaxime (OR = 10.13, <jats:italic>q</jats:italic> = 0.042, <jats:italic>n</jats:italic> = 87; permutation <jats:italic>p</jats:italic> = 0.008). The carbapenem CS signal is tetracycline-specific: tigecycline shows co-resistance (OR &lt; 0.35), consistent with its distinct RamA/AcrAB-TolC resistance mechanism. Temporal stratification (2009–2014) confirmed carbapenem– tetracycline ORs of 2.2–2.7 across independent year bands. <jats:italic>S. aureus</jats:italic> returned no qualifying SCC. These findings constitute the first large-scale clinical validation of evolutionary-trap CS structure in surveillance data and motivate experimental follow-up in isogenic bacterial models. </jats:p>