Handeland Kjell, Nesse Live L, Lillehaug Atle, Vikøren Turid, Djønne Berit, Bergsjø Bjarne
National Veterinary Institute, Section for Wildlife Diseases, Oslo, Norway.
Vet Microbiol. 2008 Nov 25;132(1-2):129-34. doi: 10.1016/j.vetmic.2008.05.002. Epub 2008 May 8.
The red fox (Vulpes vulpes) can be considered as a relevant indicator species for Salmonella in the local environment and Salmonella faecal carriage was investigated in 215 red foxes in Norway shot during the winters 2002/2003 and 2003/2004. Fourteen (6.5%) of the foxes carried Salmonella. Four isolates were determined as serovars Kottbus (n=2) and Hessarek (n=2) of Salmonella enterica subspecies enterica, and one as S. enterica subspecies IIIb:61:k:1,5,(7). The remaining nine isolates were S. enterica subspecies enterica serovar Typhimurium 4,12:i:1,2 and all displayed the same pulsed-field gel electrophoresis (PFGE) profile designated A2. This serovar regularly causes disease outbreaks amongst small passerine birds during winter and most of these outbreaks are associated with the PFGE profile A2. The results strongly indicated that the Salmonella Typhimurium infections in red foxes were primarily acquired through ingestion of infected small passerines. To investigate the capability of the A2 strain to establish a true intestinal infection in the fox an inoculation experiment with an A2 isolate from small passerines was carried out in farmed silver foxes (V. vulpes). The experiment also included one strain with an uncommonly occurring profile (X201) from small passerines. To highlight possible differences in capability of the two inoculation strains to pass the acid gastric juice in the fox, in vitro studies of their acid tolerance was carried out. Also their catalase activity and biofilm production were studied. All three foxes inoculated with the A2 strain developed sub-clinical intestinal infection of 2 weeks duration, whereas none of the three foxes inoculated with the X201 strain shed this bacterium. The X201 strain displayed a much lower capability, than the A2 strain, to survive at pH 3 in vitro. The low acid tolerance probably made it difficult for the X201 strain to pass the stomach and establish an intestinal infection in the experimental foxes. Reduced catalase activity and biofilm production were found for the X201 strain, indicating that the low acid tolerance was caused by a defect in the stationary-phase stress response system.
赤狐（Vulpes vulpes）可被视为当地环境中沙门氏菌的相关指示物种，研究人员对2002/2003年和2003/2004年冬季在挪威射杀的215只赤狐的沙门氏菌粪便携带情况进行了调查。其中14只（6.5%）狐狸携带沙门氏菌。4株分离株被鉴定为肠道沙门氏菌肠道亚种的科特布斯血清型（n = 2）和赫萨雷克血清型（n = 2），1株为肠炎沙门氏菌亚种IIIb:61:k:1,5,(7)。其余9株分离株为肠道沙门氏菌肠道亚种鼠伤寒血清型4,12:i:1,2，且均呈现相同的脉冲场凝胶电泳（PFGE）图谱，命名为A2。该血清型在冬季常导致小型雀形目鸟类疾病暴发，且大多数此类暴发与PFGE图谱A2相关。结果强烈表明，赤狐感染鼠伤寒沙门氏菌主要是通过摄入受感染的小型雀形目鸟类。为研究A2菌株在狐狸体内建立真正肠道感染的能力，用来自小型雀形目鸟类的A2分离株对养殖银狐（V. vulpes）进行了接种实验。该实验还包括一株来自小型雀形目鸟类的罕见图谱（X201）菌株。为突出两种接种菌株在狐狸体内通过酸性胃液能力的可能差异，对它们的耐酸性进行了体外研究。还研究了它们的过氧化氢酶活性和生物膜形成情况。接种A2菌株的所有三只狐狸都发生了持续2周的亚临床肠道感染，而接种X201菌株的三只狐狸均未排出该细菌。X201菌株在体外pH 3条件下的存活能力远低于A2菌株。低耐酸性可能使X201菌株难以通过胃部并在实验狐狸体内建立肠道感染。研究发现X201菌株的过氧化氢酶活性和生物膜形成减少，表明低耐酸性是由稳定期应激反应系统缺陷所致。
