The ecology and pathobiology of Clostridium difficile infections: an interdisciplinary challenge

Clostridium difficile is a well recognized pathogen of humans and animals. Although C. difficile was first identified over 70 years ago, much remains unknown in regards to the primary source of human acquisition and its pathobiology. These deficits in our knowledge have been intensified by dramatic increases in both the frequency and severity of disease in humans over the last decade. The changes in C. difficile epidemiology might be due to the emergence of a hypervirulent stain of C. difficile, ageing of the population, altered risk of developing infection with newer medications, and/or increased exposure to C. difficile outside of hospitals. In recent years, there have been numerous reports documenting C. difficile contamination of various foods, and reports of similarities between strains that infect animals and strains that infect humans as well. The purposes of this review are to highlight the many challenges to diagnosing, treating, and preventing C. difficile infection in humans, and to stress that collaboration between human and veterinary researchers is needed to control this pathogen.     

家兔大肠杆菌-魏氏梭菌二联苗研制及与两种单苗免疫比较试验

应用改进液体培养法研制家兔大肠杆菌——魏氏梭菌二联苗，大肠杆菌抗原含量一般可达220亿～250亿／mL，并对二联苗和对应的两种单苗进行了免疫比较试验。结果二联苗免疫兔对大肠杆菌和魏氏梭菌免疫效力分别达91．7％(22／24)和95．2％(20／21)，而对应的大肠杆菌单苗和魏氏梭菌单苗的保护率分别为91．3％(21／23)和87％(20／23)；免疫后持续4个月，二联苗对大肠杆菌和魏氏梭菌的保护率分别为83．3％(10／12)和81．8％(9／11)；对应的两种单苗保护率分别为75％(9／12)和80％(8／10)；临床应用效果良好。结果表明，研制的二联苗保护率高，两种组分联合制苗无干扰现象，降低了防疫成本。     

Sensitivity of Tilapia (Oreochromis mossambicus) to Clostridium botulinum toxins

The sensitivity of Oreochromis mossambicus to Clostridium botulinum toxin types A–E was investigated. All five toxin types were toxic to O. mossambicus. In the case of toxin types A–D, O. mossambicus was considerably more resistant than mice and, in the case of type E toxin, fish were more sensitive. The minimum intraperitoneal (i.p.) dose of type E toxin for fish was half the minimum lethal dose for mice. The results of the study suggest that good hygiene should be maintained in fish/shrimp farms to keep contamination at a low level.     

鸡传染性支气管炎病毒血凝性的研究

用中国和澳大利亚分离的Ａ型魏氏梭菌培养液、Ⅰ型卵磷酯酶Ｃ和胰酶处理鸡传染性支气管炎病毒（ＩＢＶ），制备的血凝抗原能凝集鸡红细胞，为鸡传染性支气管炎的诊断提供了方法。对鸡传染性支气管炎Ｍ（４１）、Ｈ（１２０）、Ｈ（５２）、Ｇｒａｙ、Ｃｏｎｎｅｃｔｉｃｕｔ、Ｔ、ＧＩＢＶ等７个毒株进行了血凝性的比较，以Ｈ（１２０）毒株血凝价最高，其次是Ｍ（４１）、ＧＩＢＶ、Ｇｒａｙ，而Ｈ（５２）、Ｃｏｎｎｅｃｔｉｃｕｔ、Ｔ等毒株血凝性低或无血凝性。作者还对影响鸡传染性支气管炎病毒血凝试验的各种因素进行了研究。     

天山马鹿肠毒血症的病原学诊断及病理学观察

2005年，新疆库尔勒某养鹿场鹿群发生了疑似肠毒血症的急性传染病，通过实验室检测手段对该病进行病原学诊断以及病理学观察，结果证实为魏氏梭菌感染。     

Lesions in the brains of three cattle resembling the lesions of enterotoxaemia in lambs

CASE HISTORY: A 3-month-old female Angus calf was found dead, and two adult Friesian dairy cows died soon after developing nervous signs.

PATHOLOGICAL FINDINGS: Grossly, bilateral and mostly symmetrical areas of haemorrhage were evident that mainly involved areas of grey matter in the brainstem from the level of the caudal colliculi to the thalamus and, in one, the internal capsule and caudate nucleus. In the occipital and caudal parietal cortex, there was extensive oedema of white matter. Histologically, in addition to haemorrhage, there was protein-rich oedema around arterioles and venules in the cerebrum, hippocampus, internal capsule, thalamus, midbrain, dorsal medulla, and central cerebellar and cerebellar folial white matter. The calf's brain had bilateral and symmetrical oedema and necrosis affecting several brainstem nuclei and the occipital grey matter overlying areas of oedema of the corona radiata.

DIAGNOSIS: Although the cause was not established, the perivascular lesions resembled those produced in calves by the intravenous administration of epsilon toxin.

CLINICAL RELEVANCE: It is possible that epsilon toxin-induced enterotoxaemia occurs naturally in cattle, and where bilateral haemorrhage is recognised in the brains of cattle, small intestinal contents should be collected for analysis of epsilon toxin.     

产气荚膜梭菌多重PCR定型方法的建立及其应用

建立了多重PCR检测产气荚膜梭菌α、β、ε和ι毒素基因的方法。该方法具有良好的特异性和敏感性,只有产气荚膜梭菌呈现阳性,被检验的其他梭菌以及大肠杆菌、葡萄球菌均为阴性;将肉汤菌液样品10倍系列稀释后进行检测,检测灵敏度达到1.2×104CFU/mL。收集40份牛粪便样品,进行PCR检测,32份样品中成功扩增出589 bp的α毒素基因片段,阳性率为80%。结果显示,建立的多重PCR检测方法可取代血清中和试验,用于产气荚膜梭菌分型,同时表明A型产气荚膜梭菌在当地奶牛场中较为普遍。     

Effect of Vaccination Against Coccidiosis in Combination with an Antibacterial Oregano (Origanum vulgare) Compound in Organic Broiler Production

Effects on production and health in broilers vaccinated against coccidiosis (Paracox®, Schering-Plough Animal Health) in combination with an antibacterial organic compound (Orego-Stim®, Meriden Animal Health Ltd.) were investigated. To obtain an environment and infection level similar to practical conditions, experimental floor pens were set up in a commercial broiler chicken house. Orego-Stim® supplement increased live weight and feed intake up to 48 days of age, whilst feed conversion ratio was not significantly affected. Vaccinated birds had a significantly higher live weight between 34 and 48 days, compared to non-vaccinated, but vaccination did not significantly affect feed intake or feed conversion ratio. Coccidial numbers in the litter were low, and only minor intestinal lesions were found. There were no significant differences in lesion scores between the different treatments. Orego-Stim® supplement decreased caecal numbers of Clostridium perfringens at 31 days, but not at 52 days, and numbers were not affected at all by anticoccidial vaccination. Bird health was overall good. The results indicate that vaccination against coccidiosis in combination with an in-feed antibacterial compound may be an alternative control method for intestinal health in organically produced chickens.     

Clostridium difficile in faeces from healthy dogs and dogs with diarrhea

Background

This study was conducted to evaluate the faecal occurrence and characterization of Clostridium difficile in clinically healthy dogs (N = 50) and in dogs with diarrhea (N = 20) in the Stockholm-Uppsala region of Sweden.

Findings

Clostridium difficile was isolated from 2/50 healthy dogs and from 2/20 diarrheic dogs. Isolates from healthy dogs were negative for toxin A and B and for the tcdA and tcdB genes. Both isolates from diarrheic dogs were positive for toxin B and for the tcdA and tcdB genes. The C. difficile isolates from healthy dogs had PCR ribotype 009 (SE-type 6) and 010 (SE-type 3) whereas both isolates from dogs with diarrhoea had the toxigenic ribotype 014 (SE-type 21). One of the isolates from healthy dogs was initially resistant to metronidazole.

Conclusions

This study revealed presence of toxigenic C. difficile in faecal samples of diarrheic dogs and low number of non- toxigenic isolates in healthy dogs from Uppsala-Stockholm region in Sweden. However, more comprehensive studies are warranted to investigate the role of C. difficile in gastrointestinal disease in dogs.