肉毒杆菌及肉毒毒素研究进展

肉毒杆菌是一种致命病菌,能引起肉毒中毒症。肉毒杆菌作为影响食品安全的一个重要风险因素,尤其是在新西兰恒天然公司部分产品受到肉毒杆菌污染事件发生后,肉毒杆菌及肉毒毒素受到了普遍关注。现就肉毒杆菌及肉毒毒素的生物学特性、中毒机制、诊断及治疗研究进展进行综述。     

肉毒梭菌毒素中毒

肉毒梭菌毒素中毒是由肉毒梭菌产生的外毒素引起的一种严重的食物中毒.肉毒梭菌广泛分布于自然界中,其芽孢在江河湖海的淤泥沉积物、尘土和动物的粪便中都有存在.水和土壤中存在的芽孢,是造成食物污染的主要来源.     

犬肉毒梭菌毒素中毒病例介绍

<正> 犬肉毒梭菌毒素中毒在临床上极少见,笔者曾遇见两例,现报道如下:1 临床症状病初站立不稳,步态螨跚,随着病情的发展,以后肢到前肢发生进行性瘫痪,针刺反应减弱。病犬精神不振,食欲废绝,口角流有泡沫唾液,两耳下垂,眼结膜潮红,视力减退,反应迟钝,呼吸急促,心跳加快,节     

犬肉毒梭菌毒素中毒的诊治

肉毒梭菌毒素中毒是犬饲料中毒中常见的一种。该病发病急,若诊疗不当,则病死率高。本文重点对该病的临床特点及防治措施等进行了阐述,可供基层兽医工作者临床参考。     

肉毒杆菌检测与控制技术研究进展

肉毒杆菌是一种只能在厌氧条件下生长的细菌,大量繁殖分泌的肉毒毒素是迄今为止所发现的生物毒素中毒性最强的物质之一.本文就该菌的生物学特征、临床感染症状、最新研究进展、生产控制与产品检验等方面进行阐述,以便使广大奶业从业者及消费者对其有全面的认识.     

奶牛和乳制品中的肉毒杆菌

本文回顾了全球范围内牛的肉毒中毒事件和因食用乳及乳制品引发的人的肉毒中毒事件,分析了肉毒污染的可能原因.重点阐述了乳及乳制品中的肉毒毒素或肉毒杆菌引起人肉毒中毒或感染肉毒杆菌及引发乳品加工链中肉毒污染的风险,并对如何防控乳及乳制品发生肉毒污染提出了建议举措.     

一例散养蛋鸡肉毒梭菌毒素中毒的诊治

5月26日,我们接到一个以吃食了大量死鸭肚里的蛆而发生死亡散养产蛋鸡病例。经剖检发现嗉囊内有大量死蛆,疑为肉毒梭菌毒素中毒,后通过成功的处理措施,病情能     

谈肉毒中毒的病因与蜂蜜

谈肉毒中毒的病因与蜂蜜〔美国〕比特尔斯通，Ｆ．什么是肉毒中毒？肉毒中毒是由一种叫做肉毒杆菌的细菌所引起的，这种菌存在于土壤中。肉毒杆菌素不会引起胃肠道的炎症。但是，如该毒素被神经吸收，会对植物神经末梢产生一种不可逆的作用，使运动神经不能促使肌肉兴奋。...     

一起狐狸C型肉毒毒素中毒的诊治

肉毒毒素是由厌氧的肉毒梭菌在生长繁殖过程中产生的一种细菌外毒素,能引起动物发生肉毒中毒。根据毒素抗原性的不同,可将肉毒梭菌及其毒素分为A、B、C、D、E、F和G型7个型。其中A、B、E及F型为人的中毒型别,C和D型为动物的中毒型别。C型肉毒梭菌在自然界广泛分布,饮食被C型肉毒梭菌特别是C型肉毒毒素污染的水或草料的动物有可能发生C型肉毒中毒。     

Proteases of Clostridium Botulinum: II. The Relationship Between Growth Medium and the Production of Proteases by Clostridium Botulinum Types A,B, C,D, E and F

The present investigation was carried out in order to find a suitable medium for the production of proteolytic enzymes from different types of Clostridium botulinum. Proteolytic activity was found in Clostridium botulinum types A, B, C, D and F, while supernatants of Clostridium botulinum type E did not possess any proteolytic activity at all.Skim milk medium possessed the greatest ability for the production of proteolytic enzymes from the different cultures of Clostridium botulinum tested, while Robertson’s meat broth produced lowest amounts. Highest titres were usually found after 4–5 days of incubation and, after this period, the level of proteolytic activity decreased.     

肉毒梭菌毒素灭鼠研究进展

就肉毒梭菌毒素用于灭鼠的研究和应用情况进行了综述，充分肯定了C型肉毒梭菌毒素灭鼠制剂毒力强，适口性好，对非靶动物毒性低，作用缓慢，无2次中毒，易降解和适合于规模灭鼠的特点，为鼠害防治提供了新的思路。     

荧光定量聚合酶链反应检测乳品中肉毒梭菌

通过实时荧光定量聚合酶链反应方法检测乳粉与乳清粉中的A、B、E、F四型肉毒梭菌,对肉毒梭菌荧光定量聚合酶链反应试剂盒中的阳性对照品及10、102、103、104倍梯度稀释的阳性对照品做出AB混合型和EF混合型的标准曲线,循环域值具有极好的特异性、重复性和准确性.对通过国标方法与中华人民共和国出入境检验检疫行业标准方法检测长出疑似菌落的82份乳粉与乳清粉采用实时荧光定量聚合酶链反应法检测,均检测不到样品中含A、B、E、F四型肉毒梭菌.     

Proteases of Clostridium botulinum. VI. The role of trypsin, Clostridium botulinum proteases and protease inhibitors in the formation and activation of toxin in growing cultures of Clostridium botulinum

In this study the influence of bovine serum protease inhibitors, trypsin and proteases produced by different types of Clostridium botulinum has been investigated. Trypsin and botulinum proteases had the capability of increasing the toxicity in growing cultures in Clostridium botulinum types A, B and E. Trypsin increased the toxin level to a greater extent than proteases from Clostridium botulinum types A, B, C and F. Protease inhibitors did not influence the toxin formation to any extent compared with the controls. The combined effects of proteases and protease inhibitors on the development of toxin in Clostridium botulinum type B were also investigated by adding proteases and protease inhibitors to the same culture at different time intervals. Protease inhibitors did not reduce the toxicity of the cultures as compared to the controls. Altogether a complex relationship seems to exist between protoxin, toxin, proteases and inhibitors in the culture, and the order and time sequence of addition seem to be of importance. The results obtained in this investigation indicate that proteases of Clostridium botulinum play a part in the formation and/or activation of toxin in growing cultures of proteolytic strains such as Clostridium botulinum types A and B. As to the activation of protoxin and progenitor toxin produced by non-proteolytic Clostridium botulinum types B and E, botulinum proteases showed a marked capability of increasing the toxicity in these cultures. Trypsinization may be valuable for the detection of Clostridium botulinum types A and B in foods, as well as for type E, where it is commonly used.     

产气荚膜梭菌主要致死性毒素的研究进展

产气荚膜梭菌作为危害各国家畜养殖业的主要致病菌之一,受到国内外研究者的普遍关注.产气荚膜梭菌的主要致病因子是菌体产生的外毒素.近年来,国内外对其致病机理进行了深入研究,建立起简便、快速的检测方法,并且在防治手段方面取得了巨大突破.对产气荚膜梭菌的主要致死性毒素类型、致病机理、检测技术及其防治措施等方面的研究进展进行了阐述.     

Optimization of polymerase chain reaction for detection of Clostridium botulinum type C and D in bovine samples

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The economic, medical and alimentary consequences can be catastrophic in case of an epizooty. A polymerase chain reaction (PCR)-based assay was developed for the detection of C. botulinum toxigenic strains type C and D in bovine samples. This assay has proved to be less expensive, faster and simpler to use than the mouse bioassay, the current reference method for diagnosis of C. botulinum toxigenic strains. Three pairs of primers were designed, one for global detection of C. botulinum types C and D (primer pair Y), and two strain-specific pairs specifically designed for types C (primer pair VC) and D (primer pair VD). The PCR amplification conditions were optimized and evaluated on 13 bovine and two duck samples that had been previously tested by the mouse bioassay. In order to assess the impact of sample treatment, both DNA extracted from crude samples and three different enrichment broths (TYG, CMM, CMM followed by TYG) were tested. A 100% sensitivity was observed when samples were enriched for 5 days in CMM followed by 1 day in TYG broth. False-negative results were encountered when C. botulinum was screened for in crude samples. These findings indicate that the current PCR is a reliable method for the detection of C. botulinum toxigenic strains type C and D in bovine samples but only after proper enrichment in CMM and TYG broth.     

The Inhibition of Clostridium Botulinum Type B and E in Salami Sausage

Vegetative cells and spores of Clostridium botulinum type B and E were inoculated into salami sausages with and without the preservatives sodium nitrite and sodium benzoate. The growth and toxin production of Clostridium botulinum type B and E were inhibited in this type of salami sausages, even without any addition of preservatives. The use of a starter culture with pH-lowering components has both technological and hygienic advantages.     

Proteases of Clostridium botulinum. V. Studies on the serological relationship between proteases from Clostridium botulinum and other spore-forming bacteria

By the use of the electrophoretic casein precipitating inhibition test (CPI-test) the serological relationship between proteolytic enzymes produced by different species within the genera Clostridium and Bacillus has been tested. The proteases produced by Clostridium botulinum types A, B, C, D and F cross-reacted with each other. Clostridium botulinum strain 84 was inhibited by antiproteases produced against Clostridium sporogenes, Clostridium botulinum types C and F (protease F I and F II), but not by antiproteases against Clostridium botulinum types B and F (protease II), Clostridium bifermentans and Clostridium perfringens. The protease of the newly described Clostridium botulinum strain 89 (type G) was inhibited by Clostridium sporogenes antiprotease, but not by any of the other antiproteases. It is not possible to differentiate between Clostridium botulinum, Clostridium sporogenes and Clostridium perfringens by use of serological differentiation of their proteolytic enzymes. The protease of Clostridium bifermentans is not serologically related to any of the species tested in this investigation. Proteases produced by different Bacilli were not inhibited by antiproteases from Clostridium botulinum types B, C and F, Clostridium sporogenes, Clostridium bifermentans, and the two strains of Clostridium perfringens tested. This investigation indicates a serological relationship between proteases from different Clostridium species, but not a serological relationship between proteases produced by the Clostridium species and Bacillus species tested.     

Invasive slug populations (Arion vulgaris) as potential vectors for Clostridium botulinum

Background

Norwegian meadows, including those for silage production, are recently found heavily invaded by the slug Arion vulgaris in exposed areas. As a consequence, large numbers of slugs might contaminate grass silage and cause a possible threat to animal feed quality and safety. It is well known that silage contaminated by mammalian or avian carcasses can lead to severe outbreaks of botulism among livestock. Invertebrates, especially fly-larvae (Diptera), are considered important in the transfer of Clostridium botulinum type C and its toxins among birds in wetlands. C. botulinum form highly resistant spores that could easily be consumed by the slugs during feeding. This study aimed to determine whether Arion vulgaris could hold viable C. botulinum and enrich them, which is essential knowledge for assessing the risk of botulism from slug-contaminated silage. Slug carcasses, slug feces and live slugs were tested by a quantitative real-time PCR (qPCR) method after being fed ≅ 5.8 × 10⁴ CFU C. botulinum type C spores/slug.

Results

Low amounts of C. botulinum were detected by qPCR in six of 21 slug carcasses with an even spread throughout the 17 day long experiment. Declining amounts of C. botulinum were excreted in slug feces up to day four after the inoculated feed was given. C. botulinum was only quantified the first two days in the sampling of live slugs. The viability of C. botulinum was confirmed for all three sample types (slug carcasses, slug feces and live slugs) by visible growth in enrichment media combined with obtaining a higher quantification cycle (Cq) value than from the non-enriched samples.

Conclusions

Neither dead nor live invasive Arion vulgaris slugs were shown to enrich Clostridium botulinum containing the neurotoxin type C gene in this study. Slugs excreted viable C. botulinum in their feces up to day four, but in rapidly decreasing numbers. Arion vulgaris appear not to support enrichment of C. botulinum type C.