We conducted de novo transcriptome sequencing and compared the global transcriptomes of enrofloxacin-resistant and enrofloxacin-susceptible strains.</p><p>Methods: A. hydrophila strain ATCC7966 was used as an enrofloxacin-sensitive strain and to induce an enrofloxacin-resistant strain. Functional clustering analysis was performed to obtain a unigene database. The unigenes were annotated to the Swiss-Prot and NCBI non-redundant protein databases. Gene ontology (GO) and functional pathway analyses of differentially expressed genes (DEGs) were performed, and the DEGs were verified by qRT-PCR.