Bile salts in Acinetobacter baumannii clinical strains with lack of AdeABC efflux pump

Few are the studies that analyzed the molecular features implicated to the tolerance to bile salts by A.baumannii clinical strains. Interestingly, Ab421 GEIH-2010 strain (belonging to ST79/PFGE-HUI-1 clone constitute by isolates with lacking of the AdeABC efflux pump) and A.baumannii ∆adeB ATCC 17978 showed higher tolerance to bile salts by the expression of the glutamate/aspartate transporter as well as virulence factors (Type VI Secretion System, twitching motility and biofilm) associated to the activation of the Quorum Sensing system. The studies of gene expression were carried out by microarrays which were designed (Bioarray Genetic Diagnosis, Alicante) using eArray (Agilent) from the complete genome of A. baumannii ATCC 17978 strain. The High Pure RNA Isolation Kit (Roche, Germany) was used to obtain Dnase-treated RNA from late log-phase cultures (OD=0.4-0.6) in absence and presence of 0.5% bile salts (the physiological concentrations in the human intestine are 0.1%-1.3%). The RNA samples were quantified in a NanoDrop ND-1000 Spectrophotometer (NanoDrop Technologies). Quality and integrity analysis of the samples was carried out in an Agilent 2100 Bioanalyzer with the RNA 6000 Nano reagents and the RNA Nano Chips (Agilent Technologies).