- 著者
- Toyotaka SATO Shin-ichi YOKOTA Torahiko OKUBO Kanako ISHIHARA Hiroshi UENO Yasukazu MURAMATSU Nobuhiro FUJII Yutaka TAMURA
- 出版者
- 公益社団法人 日本獣医学会
- 雑誌
- Journal of Veterinary Medical Science (ISSN:09167250)
- 巻号頁・発行日
- pp.12-0186, (Released:2012-11-14)
- 被引用文献数
- 8 30
Fluoroquinolone resistance is mainly caused by mutations in quinolone resistance-determining regions of DNA gyrase and topoisomerase IV in Escherichia coli. The AcrAB-TolC efflux pump contributes to resistance against fluoroquinolone and other antimicrobials. In this study, we investigated a high-level mechanism of fluoroquinolone resistance in E. coli that was isolated from human clinical samples and canine fecal samples. E. coli strains with high levels of fluoroquinolone resistance have been found to be frequently resistant to cephalosporins. Strains with high-level fluoroquinolone resistance exhibited lower intracellular enrofloxacin (ENR) concentrations, higher expression of AcrA, and a greater reduction in the fluoroquinolone minimum inhibitory concentration for treatment with an efflux pump inhibitor. The frequency of strains with enhanced ENR resistance selection and the survival rate of E. coli in the presence of ENR in vitro were correlated well with AcrA protein expression levels in the parental strains. These results suggest that AcrAB-TolC efflux pump over-expression is related to high-level fluoroquinolone resistance and the selection of strains with enhanced fluoroquinolone resistance.
- 著者
- Toyotaka SATO Shin-ichi YOKOTA Risa ICHIHASHI Tomoka MIYAUCHI Torahiko OKUBO Masaru USUI Nobuhiro FUJII Yutaka TAMURA
- 出版者
- 公益社団法人 日本獣医学会
- 雑誌
- Journal of Veterinary Medical Science (ISSN:09167250)
- 巻号頁・発行日
- pp.13-0144, (Released:2014-03-18)
- 被引用文献数
- 7
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.
- 著者
- Toyotaka SATO Shin-ichi YOKOTA Torahiko OKUBO Kanako ISHIHARA Hiroshi UENO Yasukazu MURAMATSU Nobuhiro FUJII Yutaka TAMURA
- 出版者
- JAPANESE SOCIETY OF VETERINARY SCIENCE
- 雑誌
- Journal of Veterinary Medical Science (ISSN:09167250)
- 巻号頁・発行日
- vol.75, no.4, pp.407-414, 2013 (Released:2013-05-02)
- 参考文献数
- 38
- 被引用文献数
- 17 30
Fluoroquinolone resistance is mainly caused by mutations in quinolone resistance-determining regions of DNA gyrase and topoisomerase IV in Escherichia coli. The AcrAB-TolC efflux pump contributes to resistance against fluoroquinolone and other antimicrobials. In this study, we investigated a high-level mechanism of fluoroquinolone resistance in E. coli that was isolated from human clinical samples and canine fecal samples. E. coli strains with high levels of fluoroquinolone resistance have been found to be frequently resistant to cephalosporins. Strains with high-level fluoroquinolone resistance exhibited lower intracellular enrofloxacin (ENR) concentrations, higher expression of AcrA, and a greater reduction in the fluoroquinolone minimum inhibitory concentration for treatment with an efflux pump inhibitor. The frequency of strains with enhanced ENR resistance selection and the survival rate of E. coli in the presence of ENR in vitro were correlated well with AcrA protein expression levels in the parental strains. These results suggest that AcrAB-TolC efflux pump over-expression is related to high-level fluoroquinolone resistance and the selection of strains with enhanced fluoroquinolone resistance.