Complete nucleotide sequence of pVQS1 containing a quinolone resistance determinant from Salmonella enterica serovar Virchow associated with foreign travel

Abstract

Objectives: Nalidixic acid-resistant Salmonella enterica serovars Kentucky (n¼ 5) and Virchow (n¼ 6) cultured from individuals were investigated for the presence of plasmid-mediated quinolone resistance (PMQR) determinants.Methods: PMQR markers and mutations within the quinolone resistance-determining regions of the target genes were investigated by PCR followed by DNA sequencing. Conjugation, plasmid profiling and targeted PCR were performed to demonstrate the transferability of the qnrS1 gene. Subsequently, a plasmid was identified that carried a quinolone resistance marker and this was completely sequenced.Results: A Salmonella Virchow isolate carried a qnrS1 gene associated with an IncN incompatibility group conjugative plasmid of 40 995 bp, which was designated pVQS1. The latter conferred resistance to ampicillin and nalidixic acid and showed sequence similarity in its core region to plasmid R46, whilst the resistance-encoding region was similar to pAH0376 from Shigella flexneri and pINF5 from Salmonella Infantis and contained an IS26 remnant, a complete Tn3 structure, a truncated IS2 element and a qnrS1 marker, followed by IS26. In contrast to pINF5, IS26 was identified immediately downstream of the qnrS1 gene.Conclusions: This is the first known report of a qnrS1 gene in Salmonella spp. in Switzerland. Analysis of the complete nucleotide sequence of the qnrS1-containing plasmid showed a novel arrangement of this antibiotic resistance-encoding region.

Characterization of the genetic environment of blaESBL genes, integrons and toxin-antitoxin systems identified on large transferrable plasmids in multi-drug resistant Escherichia coli

“…: JQ609357). The latter carries a qnrS1 gene associated with an IncN group and was originally identified in a Salmonella Virchow isolate, which was cultured from a patient in Switzerland returning from a foreign holiday (Karczmarczyk et al, 2012 ). It is interesting to note that, whereas pH2291-144 and pH2332-166 showed 99% nucleotide identity across their backbones, the bla TEM−1 genes contained on these plasmids were associated with different transposons (Figures 2A,B ).…”

Quinolone Resistance Mechanisms in Salmonella enterica Serovars Hadar, Kentucky, Virchow, Schwarzengrund, and 4,5,12:i:−, Isolated from Humans in Switzerland, and Identification of a Novel qnrD Variant, qnrD2 , in S . Hadar

“…Interestingly, this serovar contained three of the four detected plasmid-mediated resistance genes (two qnrS1 genes and one qnrB2 gene). Isolates N06-978 and N07-0090 harboring qnrS2 plasmids belong, together with a qnrS2-harboring S. Virchow isolate described previously (6), to a subcluster associated with travel to Thailand (10).…”

Plasmid-Mediated Quinolone Resistance in Shigella flexneri Isolated From Macaques

“…The qnrS gene and beta-lactam resistance gene blaTEM-1B were detected on the 60 and 52 kb plasmid contigs for S. flexneri 06-2384 and 06-3102, respectively. BLAST analysis found these plasmid contigs were homologous to the completely-sequenced ~40 kb, conjugative plasmid pVQS1 from S. enterica (Karczmarczyk et al, 2012 ) and the partially-sequenced ~47 kb, conjugative plasmid pAH0376 from Shigella flexneri 2b (Hata et al, 2005 ), both of which harbor functional blaTEM-1B and qnrS1 resistance genes. The annotated qnrS genes from the novel S. flexneri isolates showed 100% sequence identity and coverage to the qnrS1 genes found in pAH0376 and pVQS1.…”

“…In both S. flexneri genomes, qnrS was co-associated with blaTEM-1B on plasmid-like sequences that had identical homology and synteny to pAH0376 and pVQS1 from S. flexneri 2b and S. enterica , respectively. Additionally, as observed for pAH0376 and pVQS1, these plasmids could be experimentally transferred to E. coli , conferring the recipients with quinolone and beta-lactam resistance (Hata et al, 2005 ; Karczmarczyk et al, 2012 ). The activity of oqxA and oqxB combined with qnrS may enhance overall quinolone resistance in these S. flexneri isolates and may explain why the E. coli recipients demonstrated less resistance to quinolones compared to their donor counterparts.…”

“…These genes encode a ~218 amino acid protein that protects bacterial DNA gyrase and topoisomerase from quinolone and fluoroquinolone inhibition, thus resulting in low-level quinolone resistance (Tran and Jacoby, 2002 ; Tran et al, 2005a , b ; Redgrave et al, 2014 ). Since first being reported in 1998 from a clinical isolate of Klebsiella pneumoniae (Martinez-Martinez et al, 1998 ), plasmid-mediated quinolone resistance has been reported in other Enterobacteriaceae species throughout the United States (Wang et al, 2004 ) and elsewhere in the world (Hata et al, 2005 ; Mammeri et al, 2005 ; Strahilevitz et al, 2009 ; Karczmarczyk et al, 2012 ).…”