Journal Article

Characterization of antimicrobial resistance and class 1 integrons found in <i>Escherichia coli</i> isolates from humans and animals in Korea

Hee Young Kang, Young Sook Jeong, Jae Young Oh, Sung Ho Tae, Chul Hee Choi, Dong Chan Moon, Won Kil Lee, Yoo Chul Lee, Sung Yong Seol, Dong Taek Cho and Je Chul Lee

in Journal of Antimicrobial Chemotherapy

Volume 55, issue 5, pages 639-644
Published in print May 2005 | ISSN: 0305-7453
Published online May 2005 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dki076
Characterization of antimicrobial resistance and class 1 integrons found in Escherichia coli isolates from humans and animals in Korea

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Objectives: Antimicrobial resistance and class 1 integrons found in Escherichia coli isolates from humans and animals in Korea were characterized.

Methods: E. coli isolates were examined for susceptibility to antimicrobial agents. Integrase genes were amplified. Gene cassette regions for classes 1 and 2 integrons were amplified and sequenced. Conjugal transfer and Southern hybridization were performed to determine the genetic localization of class 1 integrons. The clonal relationship of E. coli isolates carrying an identical cassette array was analysed by PFGE.

Results: Commensal E. coli isolates from animals were highly resistant to commonly used antimicrobial agents such as tetracycline, sulfamethoxazole, streptomycin, ampicillin and carbenicillin. Integrons were most prevalent in commensal E. coli isolates from poultry (44%), followed by clinical isolates from humans (33%), commensal isolates from swine (23%) and humans (13%). dfrA17-aadA5, dfrA12-orfF-aadA2 and aadA1 were found most frequently in E. coli isolates from humans, poultry and swine, respectively. Class 1 integrons were mostly located in conjugative plasmids. E. coli isolates carrying an identical cassette array were phylogenetically unrelated.

Conclusions: The use of antibiotics is strongly associated with antimicrobial resistance. E. coli isolates from different sources may select a specific gene cassette by antibiotic selective pressure, which results in differences in class 1 integrons. The horizontal transfer of class 1 integrons through conjugative plasmids seems to be responsible for wide dissemination of a particular type of class 1 integron.

Keywords: antibiotics; gene cassettes; plasmids

Journal Article.  3455 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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