Novel insight into antimicrobial resistance and sensitivity phenotypes associated to qac and norA genotypes in Staphylococcus aureus

作者：Marchi Emmanuela; Furi Leonardo; Arioli Stefania; Morrissey Ian; Di Lorenzo Valeria; Mora Diego; Giovannetti Luciana; Oggioni Marco Rinaldo; Viti Carlo^*

来源：Microbiological Research, 2015, 170: 184-194.

DOI：10.1016/j.micres.2014.07.001

• Staphylococcus aureus
• Phenotype microarray
• QAC transporters
• Multidrug resistance
• NorA promoter mutations

Staphylococcus aureus strains harboring QacA, QacB, QacC, QacG transporters and norA promoter up-regulating mutations were characterized by phenotype microarray (PM), standard methods for susceptibility testing, and ethidium bromide efflux assays, in order to increase knowledge on phenotypes associated to efflux pumps and their substrates. PM data and standard susceptibility testing lead to the identification of new potential efflux targets, such as guanidine hydrochloride or 8-hydroxyquinoline for QacA and QacC pumps, respectively. The identification of compounds to which the presence of efflux pumps induced increased susceptibility opens new perspectives for potential adjunct anti-resistance treatment (i.e. strains bearing QacB transporters showed increased susceptibility to thioridazine, amitriptyline and orphenadrine). Although the tested isolates were characterized by high degree of heterogeneity, a hallmark of clinical isolates, direct ethidium bromide efflux assays were effective in highlighting differences in efflux efficiency among strains. These data add to characterization of substrate specificity in the different classes of staphylococcal multidrug efflux systems conferring specific substrate profiles and efflux features to each of them.

• 出版日期2015