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Novel quinolone resistance determinant, qepA8, in Shigella flexneri isolated in the United States, 2016.

ABSTRACT: Enterobacteriaceae, quinolone resistance is largely attributed to mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE, and plasmid-italiciated quinolone resistance (PMQR) genes (e.g., qnr genes, aac(6')-Ib-cr, or qepA).….

SUBMITTER: Webb HE

PROVIDER: S-EPMC6879244 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Novel quinolone resistance determinant, qepA8, in Shigella flexneri isolated in the United States, 2016.

Webb Hattie E HE Tagg Kaitlin A KA Chen Jessica C JC Kim Justin J Lindsey Rebecca R Francois Watkins Louise K LK Karp Beth E BE Sugawara Yo Y Folster Jason P JP

Antimicrobial agents and chemotherapy 20190916 12

Enterobacteriaceae, quinolone resistance is largely attributed to mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE, and plasmid-italiciated quinolone resistance (PMQR) genes (e.g., qnr genes, aac(6')-Ib-cr, or qepA).…. ...[more]

PMID: 31527028

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Project description:Non-human primates (NHPs) for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in the family Enterobacteriaceae. In this study, five individual isolates of multi-drug resistant Shigella flexneri were isolated from the feces of three macaques. Antibiotic susceptibility testing confirmed resistance or decreased susceptibility to ampicillin, amoxicillin-clavulanic acid, cephalosporins, gentamicin, tetracycline, ciprofloxacin, enrofloxacin, levofloxacin, and nalidixic acid. S. flexneri isolates were susceptible to trimethoprim-sulfamethoxazole, and this drug was used to eradicate infection in two of the macaques. Plasmid DNA from all isolates was positive for the plasmid-encoded quinolone resistance gene qnrS, but not qnrA and qnrB. Conjugation and transformation of plasmid DNA from several S. flexneri isolates into antibiotic-susceptible Escherichia coli strains conferred the recipients with resistance or decreased susceptibility to quinolones and beta-lactams. Genome sequencing of two representative S. flexneri isolates identified the qnrS gene on a plasmid-like contig. These contigs showed >99% homology to plasmid sequences previously characterized from quinolone-resistant Shigella flexneri 2a and Salmonella enterica strains. Other antibiotic resistance genes and virulence factor genes were also identified in chromosome and plasmid sequences in these genomes. The findings from this study indicate macaques harbor pathogenic S. flexneri strains with chromosomally- and plasmid-encoded antibiotic resistance genes. To our knowledge, this is the first report of plasmid-mediated quinolone resistance in S. flexneri isolated from NHPs and warrants isolation and antibiotic testing of enteric pathogens before treating macaques with quinolones prophylactically or therapeutically.

Project description:ObjectiveTo investigate the prevalence and mechanisms of fluoroquinolone resistance in Shigella species isolated in Bangladesh and to compare with similar strains isolated in China.MethodsA total of 3789 Shigella isolates collected from Clinical Microbiology Laboratory of icddr,b, during 2004-2010 were analyzed for antibiotic susceptibility. Analysis of plasmids, plasmid-mediated quinolone-resistance genes, PFGE, and sequencing of genes of the quinolone-resistance-determining regions (QRDR) were conducted in representative strains isolated in Bangladesh and compared with strains isolated in Zhengding, China. In addition, the role of efflux-pump was studied by using the efflux-pump inhibitor carbonyl cyanide-m-chlorophenylhydrazone (CCCP).ResultsResistance to ciprofloxacin in Shigella species increased from 0% in 2004 to 44% in 2010 and S. flexneri was the predominant species. Of Shigella spp, ciprofloxacin resistant (CipR) strains were mostly found among S. flexneri (8.3%), followed by S. sonnei (1.5%). Within S. flexneri (n = 2181), 14.5% were resistance to ciprofloxacin of which serotype 2a was predominant (96%). MIC of ciprofloxacin, norfloxacin, and ofloxacin were 6-32 mg/L, 8-32 mg/L, and 8-24 mg/L, respectively in S. flexneri 2a isolates. Sequencing of QRDR genes of resistant isolates showed double mutations in gyrA gene (Ser83Leu, Asp87Asn/Gly) and single mutation in parC gene (Ser80Ile). A difference in amino acid substitution at position 87 was found between strains isolated in Bangladesh (Asp87Asn) and China (Asp87Gly) except for one. A novel mutation at position 211 (His→Tyr) in gyrA gene was detected only in the Bangladeshi strains. Susceptibility to ciprofloxacin was increased by the presence of CCCP indicating the involvement of energy dependent active efflux pumps. A single PFGE type was found in isolates from Bangladesh and China suggesting their genetic relatedness.ConclusionsEmergence of fluoroquinolone resistance in Shigella undermines a major challenge in current treatment strategies which needs to be followed up by using empirical therapeutic strategies.

Dataset Information

Novel quinolone resistance determinant, qepA8, in Shigella flexneri isolated in the United States, 2016.

Publications

Novel quinolone resistance determinant, <i>qepA8</i>, in <i>Shigella flexneri</i> isolated in the United States, 2016.

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