title: Isolation of Escherichia coli strains with AcrAB-TolC efflux pump-associated intermediate interpretation or resistance to fluoroquinolone, chloramphenicol and aminopenicillin from dogs admitted to a university veterinary hospital.
abstract: Understanding the prevalence of antimicrobial-resistance and the relationship between emergence of resistant bacteria and clinical treatment can facilitate design of effective treatment strategies. We here examined antimicrobial susceptibilities of Escherichia coli isolated from dogs admitted to a university hospital (University hospital) and companion animal clinics (Community clinics) in the same city and investigated underlying multidrug-resistance mechanisms. The prevalence of E. coli with intermediate and resistant interpretations to ampicillin (AMP), enrofloxacin (ENR) and chloramphenicol (CHL) was higher in the University hospital than in the Community clinics cases. Use of antimicrobials, including fluoroquinolone, was also significantly higher in the University hospital than in the Community clinics cases. Upon isolation using ENR-supplemented agar plates, all ENR-resistant isolates had 3-4 nucleotide mutations that accompanied by amino acid substitutions in the quinolone-resistance-determining regions of gyrA, parC and parE, and 94.7% of all isolates derived from the University hospital showed AMP and/or CHL resistance and possessed blaTEM and/or catA1. The average mRNA expression levels of acrA, acrB and tolC and the prevalence of organic solvent tolerance, in isolates derived from ENR-supplemented agar plates were significantly higher in the University hospital than in the Community clinics isolates. Thus, E. coli derived from the University hospital cases more often showed concomitant decreased susceptibilities to aminopenicillins, fluoroquinolones and CHL than did those derived from the Community clinics; this was related to an active AcrAB-TolC efflux pump, in addition to acquisition of specific resistance genes and genetic mutations.
authors.affiliation: Laboratory of Food Microbiology and Food Safety, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu 069-8501, Hokkaido, Japan.
authors.forename: Toyotaka
authors.initials: T
authors.lastname: Sato
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yokota
authors.forename: Risa
authors.initials: R
authors.lastname: Ichihashi
authors.forename: Tomoka
authors.initials: T
authors.lastname: Miyauchi
authors.forename: Torahiko
authors.initials: T
authors.lastname: Okubo
authors.forename: Masaru
authors.initials: M
authors.lastname: Usui
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Fujii
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001559:Benzhydryl Compounds / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002701:Chloramphenicol / Q000494:pharmacology; D004283:Dog Diseases / Q000382:microbiology; D004285:Dogs; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology; D006762:Hospitals, Animal; D008297:Male; D009154:Mutation; D014495:Universities
chemical_list: C000596829:AcrAB-TolC protein, E coli; D000900:Anti-Bacterial Agents; D001559:Benzhydryl Compounds; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D002701:Chloramphenicol; C012725:aminopentamide