For this purpose, a total of eighteen ST175 isolates recovered from 8 different Spanish hospitals were analyzed; four isolates from four different French hospitals were included also for comparison. The typical resistance profile of ST175 included penicillins, cephalosporins, monobactams, carbapenems, aminoglycosides (gentamicin and tobramycin), and fluoroquinolones. In the phylogenetic analysis, the four French isolates clustered together with the two isolates from one of the Spanish regions. Sequence variation was further analyzed for 146 genes previously related to antimicrobial resistance using PAO1 genome as reference. The presence of horizontally-acquired resistance determinants was explored using Resfinder. The resistome of ST175 was found to be mainly determined by mutational events, with resistance traits common all or nearly all of the strains regardless of the place of isolation, including specific ampR mutations leading to ampC overexpression, specific mutations in oprD conferring carbapenem resistance or a mexZ mutation leading to MexXY overexpression. All isolates additionally harbored an aadB gene conferring gentamicin and tobramycin resistance. Several other resistance traits were specific to certain geographic areas such as a streptomycin resistance aadA13 gene detected in all four isolates from France and in the 2 isolates from the Cantabria region or a glpT mutation conferring fosfomycin resistance precisely detected in all but the six isolates with aadA13. Finally, several unique resistance mutations were detected in single isolates, particularly interesting among them the mutations detected in genes encoding PBPs (PBP1A, PBP3 and PBP4). Thus, these results provide valuable information for understanding both, the genetic basis of resistance and the dynamics of dissemination and evolution of MDR/XDR high-risk clones.
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