Journal Article

Tetracycline resistance of Australian <i>Campylobacter jejuni</i> and <i>Campylobacter coli</i> isolates

A. Pratt and V. Korolik

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 55, issue 4, pages 452-460
Published in print April 2005 | ISSN: 0305-7453
Published online April 2005 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dki040
Tetracycline resistance of Australian Campylobacter jejuni and Campylobacter coli isolates

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Objectives: Tetracycline resistance in Campylobacter is encoded by the tet(O) gene and is usually associated with conjugative plasmids. Little was known about tetracycline resistance in Australian Campylobacter species, therefore we investigated this resistance in 41 Campylobacter jejuni and five Campylobacter coli strains from humans and healthy chickens.

Methods: Tetracycline MICs were determined for each isolate using an agar dilution method. The distribution and localization of tet(O) on plasmid and chromosomal DNA was determined by Southern-blot experiments. The ability to transfer resistance to recipient strains was examined through conjugation studies. Identity of transconjugants was confirmed by PCR and flaA-restriction fragment length polymorphism analysis.

Results: High-level tetracycline resistance was observed, ranging from 32 to >256 mg/L. Plasmids were detected in 74% of isolates with plasmids between 30 and 40 kb in size most frequently isolated. tet(O) was present in all tetracycline-resistant isolates. In the majority of strains under study the tet(O) gene was chromosomally encoded. Tetracycline resistance of six C. jejuni strains in which tet(O) was plasmid mediated was transferred by conjugation to a C. jejuni recipient strain. Transfer did not occur between tetracycline-resistant C. jejuni strains and a C. coli recipient. No difference in MICs, plasmid carriage and tet(O) localization was detected between human and chicken isolates.

Conclusions: These data indicate that the tet(O) gene, previously reported in Campylobacter strains throughout the world, is present in Australian Campylobacter. This study will lead to a greater understanding of antibiotic resistance distribution in Campylobacter spp. in Australia.

Keywords: tet(O); plasmids; conjugation

Journal Article.  6207 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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