title: Characterization of integrons in multiple antimicrobial resistant Escherichia coli isolates from bovine endometritis.
abstract: To assess the prevalence of antimicrobial resistance and three classes of integrons in Escherichia coli (E. coli) strains (n=57) isolated from bovine endometritis in Inner Mongolia of China, antimicrobial susceptibility and the presence of three types of integrons were characterized. Most isolates were susceptible to ceftiofur, furazolidone, ciprofloxacin and enrofloxacin, while 57 isolates were all resistant to sulfamethoxydiazine and trimethoprim. High resistant incidence rates were exhibited to sulfadiazine, tetracycline, oxytetracycline, cefazolin, chloramphenicol. Forty-six of 57 E. coli strains were resistant to above 10 antibiotics (80.70%). The integrase gene and gene cassettes of integrons were amplified by PCR. DNA sequencing and analysis were used to identify the genetic content of the integron-variable regions. Neither class II nor class III integron was detected, while 36.8% (n=21) of the isolates were positive for the presence of intI1 gene. Analysis of gene cassettes revealed that six gene cassettes were found, which encoded resistance to trimethoprim (dhfr, dhfrI, dfrA17) and aminoglycosides (aadA1, aadA2, aadA5). Among them, the gene cassette array dfrA17-aadA5 was found most prevalent (66.7%). The resistance profile of positive-integron isolates was relatively broad and they were resistant to more than eight antimicrobials (n ≥ 8). The correlation analysis revealed the incidence of integrons among the isolates were related to the multiple antibiotic resistance profile, indicating integrons play an important role in the dissemination and spread of the antimicrobial resistant strains.
authors.affiliation: College of Animal Husbandry & Veterinary Medicine, Inner Mongolia Agricultural University, Huhhot 010018, PR China.
authors.forename: Hong-Xia
authors.initials: HX
authors.lastname: Zhao
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Shen
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: An
authors.forename: Hong-Liang
authors.initials: HL
authors.lastname: Fan
authors.forename: Jin-Shan
authors.initials: JS
authors.lastname: Cao
authors.forename: Pei-feng
authors.initials: PF
authors.lastname: Li
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D004716:Endometritis / Q000382:microbiology / Q000662:veterinary*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005260:Female; D032023:Integrons / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents