Acinetobacter baumannii is a Gram-negative opportunistic pathogen which is becoming an increasingly problematic cause of infections owing to its high level of antimicrobial resistance (AMR) associated with high mortality rates [1]. A major contributing factor to AMR is the presence and upregulation of multidrug efflux pumps [2]. Whilst the presence of these efflux pumps is well-established, the regulation, full substrate profile and innate physiological roles of these proteins are yet to be fully elucidated. The aim of this study was to determine the global transcriptomic effect of inactivating the genes encoding for the efflux pumps AdeABC, AdeIJK and AdeFGH from the RND superfamily of efflux pumps.
RNA-Seq transcriptomics was carried out on wild-type AB5075-UW and the efflux pump mutant strains adeB::tn, adeJ::tn and adeG::tn [3] to determine transcriptional profiles. The results of gene cluster analysis indicated the absence of these efflux pumps had downstream effects on iron homeostasis, capsule production and type IV pili gene expression. To determine whether these transcriptional changes were of phenotypic importance, changes in siderophore production, motility and biofilm formation were investigated in the mutant strains compared to the parental strain.