GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE331nnn/GSE331122/primaryOK200TranscriptomicsAcinetobacter baumanniiExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE331122GEOGSEfalseISAba1-Mediated crp-osmC Amplification Enhances Host-Associated Fitness in Acinetobacter baumanniiAcinetobacter baumannii is a pathogen, highly adaptable to both hospital and host-associated environments. Understanding the genetic mechanisms underlying its adaptability is critical for controlling its persistence. Our study identified the crp-osmC gene cluster, flanked by ISAba1 elements, as a significant genetic structure undergoing amplification in A. baumannii. By experimentally mimicking the amplification of this gene cluster, we found that it substantially enhanced bacterial growth and competitiveness, while also increasing biofilm formation and serum resistance. Furthermore, amplification of the crp-osmC cluster enhanced colonization in murine infection models. Notably, this amplification was largely limited to the epidemic ST2 lineage clinical isolates. Intriguingly, gene amplification was also accompanied by heightened susceptibility to several antibiotics. Overall, ISAba1-mediated amplification of the crp-osmC cluster enhances host-associated fitness in A. baumannii, while the accompanying increase in antibiotic sensitivity reflects a trade-off between survival and resistance.2026/05/20GSE331122GSM9739362GSM9739361GSM9739360GSM9739359GSM9739358GSM973935728641331122Acinetobacter baumannii