Fitness costs and persistence of plasmid-mediated cephalosporin resistance in Escherichia coli: an integrative review

, alongside a PRISMA-guided quantitative synthesis of 40 studies that provide data on the fitness consequences of resistance plasmids. We have analyzed a total of 154 experimental observations to identify patterns related to plasmid host background, resistance gene family, and fitness-assay framework. Because multiple observations were frequently contributed by the same study, we accounted for hierarchical structure using mixed-effects models with Study_ID as a random intercept and evaluated key patterns in the full dataset and stratified by assay type (growth curves vs. head-to-head competition assays). Moreover, we found that fitness estimates were sensitive to assay type. For instance, head-to-head competition experiments captured a broader range of deviations from neutrality than growth curve assays, although the apparent difference in mean standardized fitness between assay types was attenuated after accounting for study-level clustering. Across the curated dataset, host-associated and resistance gene-family-associated signals were method-dependent: both were evident overall and in head-to-head competition assays, but were not retained in growth-curve-only subsets. Our analysis supports a context-dependent interpretation in which plasmid-host compatibility, resistance-gene context, ecological setting, and the measurement framework jointly shape the observed fitness consequences and dissemination potential of resistance plasmids across environments.