title: Streptococcus agalactiae in the environment of bovine dairy herds--rewriting the textbooks?
abstract: Many free-stall bovine dairy herds in Norway fail to eradicate Streptococcus agalactiae despite long-term control measures. In a longitudinal study of 4 free-stall herds with automatic milking systems (AMS), milk and extramammary sites were sampled 4 times with 1-2 month intervals. Composite milk, rectal- and vaginal swabs were collected from dairy cows; rectal swabs from heifers and young stock; rectal- and tonsillar swabs from calves; and environmental swabs from the AMS, the floors, cow beds, watering and feeding equipment. A cross sectional study of 37 herds was also conducted, with 1 visit for environmental sampling. Fifteen of the herds were known to be infected with S. agalactiae while the remaining 22 had not had evidence of S. agalactiae mastitis in the preceding 2 years. All samples were cultured for S. agalactiae, and selected isolates (n=54) from positive herds were genotyped by Multi Locus Sequence Typing (MLST). Results show that the bovine gastrointestinal tract and the dairy cow environment are reservoirs of S. agalactiae, and point to the existence of 2 transmission cycles; a contagious transmission cycle via the milking machine and an oro-fecal transmission cycle, with drinking water as the most likely vehicle for transmission. Ten sequence types were identified, and results suggest that strains differ in their ability to survive in the environment and transmit within dairy herds. Measures to eradicate S. agalactiae from bovine dairy herds should take into account the extra-mammary reservoirs and the potential for environmental transmission of this supposedly exclusively contagious pathogen.
authors: Norwegian Veterinary Institute, PB 750 Sentrum, N-0106 Oslo, Norway. Electronic address: hannah.jorgensen@vetinst.no.
authors: H J
authors: HJ
authors: Jørgensen
authors: Norwegian Veterinary Institute, PB 750 Sentrum, N-0106 Oslo, Norway.
authors: A B
authors: AB
authors: Nordstoga
authors: Norwegian Veterinary Institute, PB 750 Sentrum, N-0106 Oslo, Norway.
authors: S
authors: S
authors: Sviland
authors: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK; Institute for Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK.
authors: R N
authors: RN
authors: Zadoks
authors: TINE SA, Boks 2038, 6402 Molde, Norway.
authors: L
authors: L
authors: Sølverød
authors: Norwegian Veterinary Institute, PB 750 Sentrum, N-0106 Oslo, Norway.
authors: B
authors: B
authors: Kvitle
authors: Norwegian Veterinary Institute, PB 750 Sentrum, N-0106 Oslo, Norway.
authors: T
authors: T
authors: Mørk
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission*; D003612:Dairying; D060766:Drinking Water / Q000382:microbiology; D004783:Environmental Microbiology; D005260:Female; D006799:Housing, Animal; D008892:Milk / Q000382:microbiology; D009664:Norway; D012007:Rectum / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D013292:Streptococcus agalactiae / Q000302:isolation & purification / Q000502:physiology*; D014621:Vagina / Q000382:microbiology
chemical_list: D060766:Drinking Water
keywords: Automatic milking system; Contagious mastitis; Cow; Faecal shedding; Free stall; MLST; Milk; Oro-faecal transmission; Vaginal carriage