Characterization of a toxin A-negative, toxin B-positive strain of Clostridium difficile responsible for a nosocomial outbreak of Clostridium difficile-associated diarrhea
Characterization of a toxin A-negative, toxin B-positive strain of Clostridium difficile responsible for a nosocomial outbreak of Clostridium difficile-associated diarrhea
复制标题
DOI：
10.1128/jcm.38.7.2706-2714.2000
复制
发表时间：
2000-07-01
影响因子：
9.4
通讯作者：
Embil, JM
中科院分区：
文献类型：
--
作者：
Alfa, MJ;Kabani, A;Embil, JM
艰难梭菌相关性腹泻（CAD）是一种非常常见的医院感染，对患者的发病率和死亡率以及住院费用都有重要影响。以前，人们认为毒素a阴性和毒素b阳性艰难梭菌菌株与临床显著疾病无关。本研究报告了一种毒素a阴性，毒素b阳性的艰难梭菌菌株的特征，这种菌株是最近描述的CAD院内爆发的原因。通过脉冲场凝胶电泳对暴发的7例患者分离株进行分析表明，此次暴发是由于单一难辨梭菌菌株的传播。我们对该菌株（HSC98）的表征表明，毒素A基因在羧基重复寡肽（CROP）区域缺失1.8 kb，但毒素A或毒素B基因的其他区域显然没有其他主要缺失。HSC98毒素A CROP区剩余的1.3 kb片段与hi， Weidmann于1997年报道的菌株1470序列有98%的同源性（GenBank登录号Y12616），提示HSC98为VIII型毒素。感染此次暴发的患者的HSC98菌株产生了通常与艰难梭菌相关疾病相关的全部临床疾病，尽管通过体外组织培养测试确定该菌株不能改变紧密连接，但这种致病谱仍然明显，这表明该菌株不产生功能性毒素A。
Clostridium difficile-associated diarrhea (CAD) is a very common nosocomial infection that contributes significantly to patient morbidity and mortality as well as to the cost of hospitalization. Previously, strains of toxin A-negative, toxin B-positive C. difficile were not thought to be associated with clinically significant disease. This study reports the characterization of a toxin A-negative, toxin B-positive strain of C. difficile that was responsible for a recently described nosocomial outbreak of CAD. Analysis of the seven patient isolates from the outbreak by pulsed-field gel electrophoresis indicated that this outbreak was due to transmission of a single strain of C. difficile. Our characterization of this strain (HSC98) has demonstrated that the toxin A gene lacks 1.8 kb from the carboxy repetitive oligopeptide (CROP) region but apparently has no other major deletions from other regions of the toxin A or toxin B gene. The remaining 1.3-kb fragment of the toxin A CROP region from strain HSC98 showed 98% sequence homology with strain 1470, previously reported by hi, Weidmann in 1997 (GenBank accession number Y12616), suggesting that HSC98 is toxinotype VIII. The HSC98 strain infecting patients involved in this outbreak produced the full spectrum of clinical illness usually associated with C. difficile-associated disease, This pathogenic spectrum was manifest despite the Inability of this strain to alter tight junctions as determined by using in vitro tissue culture testing, which suggested that no functional toxin A was produced by this strain.