title: Widespread distribution of disinfectant resistance genes among staphylococci of bovine and caprine origin in Norway.
abstract: We demonstrate here a widespread distribution of genes mediating efflux-based resistance to quaternary ammonium compounds (QACs) in staphylococci from unpasteurized milk from 127 dairy cattle herds and 70 dairy goat herds. QAC resistance genes were identified in 21% of the cattle herds (qacA/B, smr, qacG, and qacJ) and in 10% of the goat herds (qacA/B and smr). Further examination of 42 QAC-resistant bovine and caprine isolates revealed the following genes: qacA/B (12 isolates) was present in four different species of coagulase-negative staphylococci (CoNS), smr (27 isolates) was detected in eight different CoNS species and in Staphylococcus aureus on a previously reported plasmid (pNVH99), qacG (two isolates) was detected on two plasmids (pST94-like) in Staphylococcus cohnii and Staphylococcus warneri, and qacJ (two isolates) was found in Staphylococcus hominis and Staphylococcus delphini on a plasmid (pNVH01) previously found in equine staphylococci. Isolation of indistinguishable pulsed-field gel electrophoresis (PFGE) CoNS types from tank milk and mammary quarter milk samples in a dairy cattle herd suggested that these QAC-resistant staphylococci were of intramammary origin. Indistinguishable or closely related PFGE types of bovine QAC-resistant CoNS were observed in different herds. One particular bovine S. warneri PFGE type was isolated repeatedly from samples collected during a 30-month period in a herd, showing long-term persistence. In conclusion, it seems that the widespread distribution of staphylococci carrying QAC resistance genes in Norwegian dairy cattle and goat herds is the result of both the intra- and interspecies spread of QAC resistance plasmids and the clonal spread of QAC-resistant strains.
authors.affiliation: Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo. jostein.bjorland@veths.no
authors.forename: Jostein
authors.initials: J
authors.lastname: Bjorland
authors.forename: Terje
authors.initials: T
authors.lastname: Steinum
authors.forename: Bjørg
authors.initials: B
authors.lastname: Kvitle
authors.forename: Steinar
authors.initials: S
authors.lastname: Waage
authors.forename: Marianne
authors.initials: M
authors.lastname: Sunde
authors.forename: Even
authors.initials: E
authors.lastname: Heir
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D003612:Dairying; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D015511:Goat Diseases / Q000453:epidemiology / Q000382:microbiology; D006041:Goats; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology; D009664:Norway / Q000453:epidemiology; D010957:Plasmids; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D013210:Staphylococcus / Q000187:drug effects* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004202:Disinfectants; D000644:Quaternary Ammonium Compounds