tailieunhanh - Báo cáo khoa học: "Association Between Virulence Factors and Clinical Course of Escherichia coli Mastitis"

Tuyển tập các báo cáo nghiên cứu về bệnh thú y được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành thú y đề tài: Association Between Virulence Factors and Clinical Course of Escherichia coli Mastitis. | Acta vet. scand. 2003 44 203-205 Brief Communication Association Between Virulence Factors and Clinical Course of Escherichia coli Mastitis By T. Lehtolainen1 T. Pohjanvirta2 S. Pyôrălă1 and S. Pelkonen2 Department of Clinical Veterinary Science Faculty of Veterinary Medicine University of Helsinki Saarentaus 2Kuopio Department National Veterinary and Food Research Institute Kuopio Finland. Introduction Mastitis caused by Escherichia coli is common in lactating dairy cows. E. coli is considered to be an opportunistic pathogen and originate from a contaminated environment Nemeth et al. 1994 . The severity and course of the disease vary greatly and mainly depend on cow s response Hirvonen et al. 1990 . However the virulence of the bacterial strain involved may also play a role. Bacteria require virulence factors to colonize multiply and survive in the udder. These include toxins adhesins invasins capsule production and the ability to resist serum complement and scavenge iron. Dominant virulence factors have not been identified in mastitis-derived E. coli isolates Kaipainen et al. 2002 . In this study we investigated the association between virulence factors of the isolated bacteria and the clinical course in bovine E. coli mastitis. Materials and methods A total of155 E. coli isolates from acute bovine mastitis was collected during routine farm calls by the ambulatory clinic of the University of Helsinki. The attending veterinarian took aseptically a quarter milk sample for bacterial isolation and determination of milk N-acetyl-fi-D- glucosaminidase NAGase activity and recorded the clinical signs of the cow and the changes in milk appearance. Mastitis was classified as severe if the cow was depressed and had high fever no appetite a swollen and painful udder and substantial changes in the milk appearance. In mild mastitis cows had no or a slight fever and only moderate changes in the udder and milk. The cows were divided into 3 lactation stage groups 0-21 22-210 and