Transferable Mechanisms of Quinolone Resistance from 1998 Onward

Abstract

SUMMARY While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6′)Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.

Genomic analyses of multidrug-resistant Salmonella Indiana, Typhimurium, and Enteritidis isolates using MinION and MiSeq sequencing technologies

“…The pan-genomes of the MiSeq and hybrid assemblies of 25 Salmonella isolates consisted of 7,341 genes with 3,729 core genes (50.8%) and 3,612 accessory genes (49.2%) and 7,606 genes with 3,762 core genes (49.5%) and 3,844 accessory genes (50.5%), respectively. In contrast, the total number of genes in the pan-genome of the MinION assemblies was significantly higher (40,299) with as many as 39,815 accessory genes (98.8%) and only 484 core genes (1.2%). Based on our core-genome phylogenetic analyses, the Min-ION assemblies on the core-genome phylogenetic tree were more genetically isolated from one another compared to the MiSeq and hybrid assemblies on their corresponding trees https://doi.org/10.1371/journal.pone.0235641.g004…”

ICEs Are the Main Reservoirs of the Ciprofloxacin-Modifying crpP Gene in Pseudomonas aeruginosa

“…Besides chromosomal mutations, ciprofloxacin resistance can be mediated by horizontally transferred genes, such as the quinolone resistance qnr gene [9] and the ciprofloxacin-modifying crpP gene [10]. The crpP gene induces ATP-dependent phosphorylation of the antibiotic and was originally identified in a plasmid isolated from a P. aeruginosa clinical isolate [11].…”

Epidemic and molecular characterization of fluoroquinolone-resistant Shigella dysenteriae 1 isolates from calves with diarrhea

“…Otherwise, the plasmid-mediated qepA gene can encode a 14-transmembrane segment e ux pump and extrude several quinolones from bacteria, thereby conferring low levels of resistance to these antimicrobial agents and favoring the selection of new alterations that are able to induce full quinolone resistance. 45,46 Compared with other PMQR determinants, qepA is a new resistance gene, rst described in 2007, 47 so it is not di cult to understand the lowest frequencies.…”