biostudies-literatureHuang HNational Natural Science Foundation of Chinae0007225https://www.ebi.ac.uk/biostudies/studies/S-EPMC12057350biostudies-literatureUnknown69(5)Compared with tigecycline-resistant gram-negative bacteria, tigecycline adaptive laboratory evolution (ALE) has been preliminarily performed in Staphylococcus aureus. This study aims to develop higher-level tigecycline-resistant S. aureus mutants (TRSAms) and explore the mechanisms behind decreasing susceptibility to tigecycline. In this study, S. aureus strains were cultured in serial-increasing concentrations of tigecycline and successfully obtained high-level TRSAms. Different phenotypic changes in high-level TRSAms were assessed by growth rate measurement, autolysis assays, mutant frequency determination, and virulence evaluations in vivo and in vitro. The phenotypes of fitness cost showed significant differences in these high-level TRSAms. Whole-genoAntimicrobial agents and chemotherapyPhenotypic and genetic stepwise changes in Staphylococcus aureus during in vitro adaptive laboratory evolution under the selective pressure of tigecycline.PMC1205735032121004Wan PZhu YHuang HLin WZeng ZChen YLuo XfalsePhenotypic and genetic stepwise changes in Staphylococcus aureus during in vitro adaptive laboratory evolution under the selective pressure of tigecycline.Compared with tigecycline-resistant gram-negative bacteria, tigecycline adaptive laboratory evolution (ALE) has been preliminarily performed in Staphylococcus aureus. This study aims to develop higher-level tigecycline-resistant S. aureus mutants (TRSAms) and explore the mechanisms behind decreasing susceptibility to tigecycline. In this study, S. aureus strains were cultured in serial-increasing concentrations of tigecycline and successfully obtained high-level TRSAms. Different phenotypic changes in high-level TRSAms were assessed by growth rate measurement, autolysis assays, mutant frequency determination, and virulence evaluations in vivo and in vitro. The phenotypes of fitness cost showed significant differences in these high-level TRSAms. Whole-geno2025-01-01T00:00:00Z2025 May2026-06-02T20:47:36.332Z2026-04-20T03:14:27.445ZS-EPMC120573504013589910.1128/aac.00072-25