ISAba1-Mediated crp-osmC Amplification Enhances Host-Associated Fitness in Acinetobacter baumannii

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.