JAC Advance Access published online on November 12, 2005
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dki407
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1 Norwegian School of Veterinary Science, PO Box 8146 Dep, N-0033 Oslo, Norway
* To whom correspondence should be addressed. Objectives: The aim was to study the persistence and characteristics of Staphylococcus warneri strains resistant to quaternary ammonium compounds (QACs), including sequencing and analysis of two plasmids proved to carry the smr gene. Methods: During a 3.5 year period quarter milk samples were collected on three occasions from all lactating cows in a dairy herd. The samples were screened with regard to QAC-resistant bacteria using a selective medium. Thirty randomly selected QAC-resistant S. warneri were typed by PFGE and subjected to plasmid isolation and analysis followed by gene detection using PCR. Two smr-containing plasmids in S. warneri isolates were sequenced. Results: All isolates from the initial collection of quarter milk contained smr residing on a 5.8 kb plasmid (pSW174), which contained regions with high similarities to various plasmids, including pT181, pSK108 and pPI-2. The pT181-like sequence was flanked by 148 bp direct repeats, denoted ISLE49, with high similarity to previously reported sequences of Conclusions: The IS-associated elements found in this study may have a wider role in the integration and excision of DNA sequences in staphylococci than previously reported. The mosaic plasmid structure based on genetic elements of various origins contributes to further knowledge on the flexibility of smr-encoding plasmids.
Received August 29, 2005
Revised October 10, 2005
Accepted October 14, 2005
Original article
Deletion of PT181-like sequence in an smr-encoding mosaic plasmid harboured by a persistent bovine Staphylococcus warneri strain
Jostein Bjorland 1 *,
Terje Steinum 2,
Marianne Sunde 2,
Steinar Waage 1,
Ståle Sviland 2,
Hanne Oppegaard 3,
and
Even Heir 4
2 National Veterinary Institute, PO Box 8156 Dep, N-0033 Oslo, Norway
3 TINE Research and Development, N-0950 Oslo, Norway
4 Matforsk AS, Norwegian Food Research Institute, N-1430 Ås, Norway
Jostein Bjorland, E-mail: jostein.bjorland{at}veths.no
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Abstract
148 bp, including ISLE39 flanking the insertion sequence IS257 in methicillin-resistant Staphylococcus aureus. All isolates from subsequent collections of quarter milk harboured a smaller smr-containing plasmid (pSW49). Sequence analyses revealed pSW49 (3552 bp) to be an in-part deleted version of pSW174 (5767 bp).![]()
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