Johansson Anders, Aspan Anna, Bagge Elisabeth, Båverud Viveca, Engström Björn E, Johansson Karl-Erik
National Veterinary Institute, SE-751 89 Uppsala, Sweden.
BMC Microbiol. 2006 May 31;6:47. doi: 10.1186/1471-2180-6-47.
Clostridium perfringens, a serious pathogen, causes enteric diseases in domestic animals and food poisoning in humans. The epidemiological relationship between C. perfringens isolates from the same source has previously been investigated chiefly by pulsed-field gel electrophoresis (PFGE). In this study the genetic diversity of C. perfringens isolated from various animals, from food poisoning outbreaks and from sludge was investigated.
We used PFGE to examine the genetic diversity of 95 C. perfringens type A isolates from eight different sources. The isolates were also examined for the presence of the beta2 toxin gene (cpb2) and the enterotoxin gene (cpe). The cpb2 gene from the 28 cpb2-positive isolates was also partially sequenced (519 bp, corresponding to positions 188 to 706 in the consensus cpb2 sequence). The results of PFGE revealed a wide genetic diversity among the C. perfringens type A isolates. The genetic relatedness of the isolates ranged from 58 to 100% and 56 distinct PFGE types were identified. Almost all clusters with similar patterns comprised isolates with a known epidemiological correlation. Most of the isolates from pig, horse and sheep carried the cpb2 gene. All isolates originating from food poisoning outbreaks carried the cpe gene and three of these also carried cpb2. Two evolutionary different populations were identified by sequence analysis of the partially sequenced cpb2 genes from our study and cpb2 sequences previously deposited in GenBank.
As revealed by PFGE, there was a wide genetic diversity among C. perfringens isolates from different sources. Epidemiologically related isolates showed a high genetic similarity, as expected, while isolates with no obvious epidemiological relationship expressed a lesser degree of genetic similarity. The wide diversity revealed by PFGE was not reflected in the 16S rRNA sequences, which had a considerable degree of sequence similarity. Sequence comparison of the partially sequenced cpb2 gene revealed two genetically different populations. This is to our knowledge the first study in which the genetic diversity of C. perfringens isolates both from different animals species, from food poisoning outbreaks and from sludge has been investigated.
产气荚膜梭菌是一种严重的病原体，可导致家畜肠道疾病和人类食物中毒。以前主要通过脉冲场凝胶电泳（PFGE）研究来自同一来源的产气荚膜梭菌分离株之间的流行病学关系。在本研究中，对从各种动物、食物中毒暴发以及污泥中分离出的产气荚膜梭菌的遗传多样性进行了研究。
我们使用PFGE检测了来自八个不同来源的95株A型产气荚膜梭菌分离株的遗传多样性。还检测了这些分离株中β2毒素基因（cpb2）和肠毒素基因（cpe）的存在情况。对28株cpb2阳性分离株的cpb2基因也进行了部分测序（519 bp，对应于共有cpb2序列中的第188至706位）。PFGE结果显示A型产气荚膜梭菌分离株之间存在广泛的遗传多样性。分离株的遗传相关性在58%至100%之间，共鉴定出56种不同的PFGE类型。几乎所有具有相似模式的聚类都包含具有已知流行病学相关性的分离株。来自猪、马和羊的大多数分离株携带cpb2基因。所有源自食物中毒暴发的分离株都携带cpe基因，其中三株还携带cpb2基因。通过对本研究中部分测序的cpb2基因以及先前存入GenBank的cpb2序列进行序列分析，鉴定出两个进化上不同的群体。
如PFGE所示，来自不同来源的产气荚膜梭菌分离株之间存在广泛的遗传多样性。正如预期的那样，流行病学相关的分离株显示出高度的遗传相似性，而没有明显流行病学关系的分离株则表现出较低程度的遗传相似性。PFGE显示的广泛多样性在16S rRNA序列中并未体现，这些序列具有相当程度的序列相似性。对部分测序的cpb2基因进行序列比较，揭示了两个遗传上不同的群体。据我们所知，这是首次对来自不同动物物种、食物中毒暴发以及污泥中的产气荚膜梭菌分离株的遗传多样性进行研究。
