Analysis of Clostridium difficile strains causing multiple nosocomial outbreaks in Japan by genotypic typing methods

将对slpA基因的可变区进行测序的分型系统应用于分型属于一种PCR核糖体型（smz型）的艰难梭菌菌株，该菌株已被鉴定为在日本经常引起暴发。对从日本不同医院的患者中回收的PCR核糖体型smz菌株进行了检查。在10个SMZ型菌株中，鉴定出3个亚型，SMZ-1、-2和-3，它们彼此之间仅相差一个核苷酸。slpA序列分型也被应用于从粪便标本中提取的DNA的直接分型。在检查的22份粪便标本中，17份为slpA PCR阳性; 8份为slpA序列类型smz-1，9份为smz-2。从17份粪便标本中的12份培养艰难梭菌，并将回收的分离株的序列结果与从粪便标本中提取的DNA的序列结果进行比较。在所有12份粪便标本中，回收的艰难梭菌分离株的DNA序列结果与直接从粪便标本中提取的DNA序列结果完全一致。其余5份粪便标本艰难梭菌培养阴性。序列分型的优点是容易通过互联网在多个实验室之间比较分型结果，而无需将参考菌株与分型系统的参考菌株交换，分型系统的结果取决于带型分析。slpA序列分型似乎是艰难梭菌的可重复和可靠的分型系统，并且当粪便样本仅含有少量艰难梭菌或不适合培养时，可用于艰难梭菌的分型。

The typing system sequencing the variable region of the slpA gene was applied to typing Clostridium difficile strains belonging to one PCR ribotype, type smz, which has been identified as frequently causing outbreaks in Japan. The PCR ribotype smz strains recovered from patients at different hospitals in Japan were examined. Among 10 type smz strains tested, three subtypes, smz-1,-2,and -3,were identified that differed from each other by one nucleotide. slpA sequence typing was also applied to direct typing on DNA extracted from stool specimens. Of 22 stool specimens examined, 17 were PCR positive for slpA ; eight were typed as slpA sequence type smz-1,and nine were type smz-2. C.difficile was cultured from 12 of the 17 stool specimens, and the sequence results of the recovered isolates were compared with those from DNA extracted from stool specimens. In all 12 stool specimens, the sequence results of DNA from recovered C.difficile isolates completely agreed with those of DNA extracted directly from stool specimens. The remaining five stool specimens were culture-negative for C.difficile. Sequence typing has the advantage of being easy to compare typing results among multiple laboratories via the Internet without exchanging reference strains to those of typing systems the results of which depend on banding-pattern analyses. slpA sequence typing appears to be a reproducible and reliable typing system for C.difficile as well as being useful for the typing of C.difficile when stool specimens contain only small numbers of C.difficile or are inappropriate for culturing.