Journal Article

High frequency transfer and horizontal spread of apramycin resistance in calf faecal <i>Escherichia coli</i>

C. M. Yates, M. C. Pearce, M. E. J. Woolhouse and S. G. B. Amyes

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 54, issue 2, pages 534-537
Published in print August 2004 | ISSN: 0305-7453
Published online August 2004 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dkh353
High frequency transfer and horizontal spread of apramycin resistance in calf faecal Escherichia coli

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Objectives: The aminoglycoside apramycin has been used extensively in animal husbandry in the UK since 1978. This study aimed to determine both whether calves that had never been treated with aminoglycoside antibiotics harboured apramycin-resistant (aprR) commensal Escherichia coli, and the mode of spread of the resistance gene.

Methods: AprR E. coli from weekly calf faecal samples were typed by pulsed-field gel electrophoresis, antibiotic resistance phenotype, plasmid restriction profiles and plasmid transfer frequencies.

Results: During 4 months of weekly sampling, six of 11 calves were found to harbour aprR E. coli. All aprR E. coli (45) were cross-resistant to gentamicin and tobramycin, which are both used in human medicine. Resistance was conferred by the aac(3)IV gene, present on three different conjugative plasmids. Two of these plasmids also mediated tetracycline and streptomycin resistance. One plasmid demonstrated very high transfer frequencies and was found in three different genotypes.

Conclusions: We report the presence of aprR commensal E. coli in cattle that have never been treated with aminoglycosides. The presence of one conjugative plasmid in three different genotypes is evidence of horizontal spread of this plasmid. This is the first report of a very high transfer frequency of aprR plasmid, demonstrating horizontal spread in the commensal flora of food animals.

Keywords: conjugation; commensals; AAC(3)IV; food animals; plasmids

Journal Article.  1977 words. 

Subjects: Medical Oncology ; Critical Care

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