Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
Vet Rec. 2012 Aug 25;171(8):194. doi: 10.1136/vr.100865. Epub 2012 Aug 2.
Salmonella in cattle herds may behave as epidemic or endemic infections. An intensive longitudinal sampling study across all management groups and ages on six dairy farms in the UK was used to examine patterns of Salmonella shedding, following the prior identification of either Salmonella Dublin (SD) (three farms) or Salmonella Typhimurium (ST) (three farms) on the premises in the context of clinical salmonellosis. Individual faeces, pooled faeces and environmental samples (total 5711 samples), taken approximately every six weeks for 15-24 weeks, were cultured for Salmonella. SD was detected at low frequency (on any visit, 0.5-18.3 per cent of samples positive) and most consistently in calves. By contrast, ST was isolated at higher frequency (on any visit, 6.8-75 per cent of samples positive), and in higher numbers, up to 10(7) cfu/g faeces. Significantly more samples from calves were positive for ST than were positive for SD (50.6 per cent v 3.1 per cent; P < 0.001), which was also true for milking cows (46.3 per cent v 4.4 per cent; P < 0.001). The differences could help to explain the different patterns of bovine infection classically associated with these two serovars in the UK. No consistent effect upon shedding was seen among the ST-infected herds following vaccination.
牛群中的沙门氏菌可能表现为流行或地方性感染。在英国六家奶牛场的所有管理群体和年龄组中进行了一项密集的纵向采样研究，这些奶牛场先前在临床沙门氏菌病的背景下，场内发现了都柏林沙门氏菌（SD）（三家农场）或伤寒沙门氏菌（ST）（三家农场）。个体粪便、混合粪便和环境样本（共 5711 个样本），每 6 周左右采集一次，持续 15-24 周，用于培养沙门氏菌。SD 的检出频率较低（任何一次访问，阳性样本的比例为 0.5-18.3%），且最常发生在犊牛中。相比之下，ST 的分离频率更高（任何一次访问，阳性样本的比例为 6.8-75%），数量更多，高达 10（7）cfu/g 粪便。犊牛的 ST 阳性样本明显多于 SD（50.6%比 3.1%；P<0.001），奶牛也如此（46.3%比 4.4%；P<0.001）。这些差异有助于解释在英国与这两种血清型相关的不同牛感染模式。在接种疫苗后，受 ST 感染的牛群的粪便脱落没有一致的影响。
