Toxin A–Negative, Toxin B–Positive<i>Clostridium difficile</i>Infection Diagnosed by Polymerase Chain Reaction

Cheng, Ying; Du, Pengcheng; Chen, Chen; Shi, Yan; Jia, Hao; Wang, Jing; Yan, Qing Song; Feng, Hanping; Lu, Jinxing

doi:10.1086/659959

Cited by 5 publications

(10 citation statements)

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“…According to the size of deletions at the 3= end of tcdA, A Ϫ B ϩ strains are divided into deletion and truncated forms (9). Yet, our previous study demonstrated significant genetic diversity in tcdA and tcdB, consistent with the results of toxinotyping based on the restriction fragment length polymorphism (RFLP)-PCR method (19,28). However, the simple classification of RFLP-PCR failed to explain more details about the epidemiological relevance and phylogenetic relationships between strains with different types of toxin genes, while the recently increased ST37 (RT017 [A Ϫ B ϩ ]) contribution (48%) for CDI cases and its epidemic potentiality in Asia (11,16) make it urgent to build a more finely described pattern to reveal the intrinsic epidemic characteristics.…”

Section: Discussionsupporting

confidence: 87%

“…In a number of tcdA and tcdB sequence types, SNPs were found in the sequences corresponding to the PCR primers widely used for toxin detection. For example, at the loci corresponding to primers NK104 and NK105 (19), which are commonly used for tcdB detection, there are between one and three SNPs in B09 to B15 and six in B16. At the loci of a frequently used primer set for tcdA detection, i.e., NK2 and NK3 (19), there are one or two SNPs in A02, A09, A12, A13, A14, and A16.…”

Section: Resultsmentioning

confidence: 99%

“…For example, at the loci corresponding to primers NK104 and NK105 (19), which are commonly used for tcdB detection, there are between one and three SNPs in B09 to B15 and six in B16. At the loci of a frequently used primer set for tcdA detection, i.e., NK2 and NK3 (19), there are one or two SNPs in A02, A09, A12, A13, A14, and A16. Such a high level of polymorphisms at genome loci that are important for tcdA and tcdB identification might cause false-negative results in toxin gene detection and typing by PCR.…”

Section: Resultsmentioning

confidence: 99%

“…Currently, the literature on CDI caused by A Ϫ B ϩ strains is limited, and there is some confusion over the correct identification of specific isolates. For example, the apparently high isolation rate of A Ϫ B ϩ strains in Asia and Latin America may reflect mismatching of PCR primers as a result of C. difficile polymorphisms (19). Nevertheless, it seems clear that C. difficile RT017 is prevalent in Asia and China, but the reasons for this distribution, as well as its relation to the highly virulent RT027 strain in Europe and North America, are still uncertain.…”

mentioning

confidence: 99%

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Sequence Variation in tcdA and tcdB of Clostridium difficile: ST37 with Truncated tcdA Is a Potential Epidemic Strain in China

Cao

Wang

et al. 2014

J Clin Microbiol

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Clostridium difficile is a well-known nosocomial infectious pathogen. Research on C. difficile infection has primarily focused on strains such as the hypervirulent PCR ribotype 027 (sequence type 1 [ST1]) emerging in Europe and North America. However, other new emerging ribotypes in some countries have attracted attention, such as PCR ribotype 17 (ST37) in Asia and Latin America. We collected 70 strains and sequenced their toxin genes, tcdA and tcdB. Multilocus sequence typing (MLST) was used to study their population structure. In addition, tcdA and/or tcdB sequences of 25 other isolates were obtained from GenBank. Single nucleotide polymorphisms (SNPs) were identified and analyzed. Phylogenetic analyses were performed to study toxin gene evolution. All tcdA and tcdB sequences were divided into 1 of 16 types (denoted A01 to -16 and B01 to -16, respectively). Hypervirulent strain RT027 is A13B12, and RT078 is A14B10, whereas the newly epidemic strain RT017 is A15B13. SNP analysis suggests the possibility of recombination in tcdB, perhaps through horizontal gene transfer. SNPs were also found in the sequences corresponding to the PCR primers widely used for toxin detection. Our study shows that ST037 shares a few genotypic features in its tcdA and tcdB genes with some known hypervirulent strains, indicating that they fall into a unique clade. Our findings can be used to map the relationships among C. difficile strains more finely than can be done with less sensitive methods, such as toxinotyping or even MLST, to reveal their inherent epidemiological characteristics.

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Section: Discussionsupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Sequence Variation in tcdA and tcdB of Clostridium difficile: ST37 with Truncated tcdA Is a Potential Epidemic Strain in China

Cao

Wang

et al. 2014

J Clin Microbiol

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“…Previous studies have demonstrated that it is difficult to identify multiple strains of C. difficile (11)(12)(13), and researchers from the present study group have previously conducted fundamental studies on C. difficile (13). The gene polymorphism of toxins A and B of C. difficile has previously been studied in a clinical setting, as have the gene polymorphism and evolutionary characteristics of toxin A-negative and toxin B-positive C. difficile (13).…”

Section: Discussionmentioning

confidence: 86%

Preliminary screening of type IV secretion system in divergent geographic sources of Clostridiumï¿½difficile

Jia

Yang

et al. 2017

Exp Ther Med

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Abstract. In the present study, different geographical sources and sequence types (STs) of Clostridium difficile were preliminarily screened to investigate the distribution profiles of three core genes, VirB4, VirB6 and VirD4, of the type IV secretion system (T4SS). A total of 37 C. difficile strains from different sources were screened, inoculated and prepared for genome extraction. C. difficile toxins A and B were subjected to identification and multilocus sequence typing (MLST) analysis. The T4SS gene then underwent polymerase chain reaction amplification and sequencing analysis. Of the 37 strains, 25 were toxin A-and toxin B-positive, and 12 were toxin A-negative and toxin B-positive. MLST detected 11 strains with ST37, 10 with ST2, 6 with ST35, 7 with ST3, 1 with ST54, 1 with ST1 and 1 with ST119. The detection rates of VirB4, VirB6 and VirD4 were all 100% in colonies exhibiting T4SS. Single nucleotide polymorphisms (SNPs) were detected in a minority of strains. C. difficile strains with identical STs shared the same SNP loci for T4SS, and those with different STs had different SNP loci. The results of the present study may provide evidence for subsequent identification of T4SS distribution, epidemiological investigations, polymorphism analyses and research into the association between T4SS, cytotoxicity and enterotoxication in C. difficile.

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Multilocus sequence typing (MLST) analysis of 104Clostridium difficilestrains isolated from China

et al. 2012

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SUMMARYThe phylogenetic and epidemic relationships of 104 clinical isolatesof Clostridium difficilefrom three hospitals of different geographical and population sources in China were investigated by multilocus sequence typing. Twenty-two sequence types (STs) were identified, four of which, ST117, ST118, ST119 and ST129, were novel. No geographically specific and host population-specific phylogenetic lineages were found and there was no correlation between geographical origin or host population and strain genotype. ST37 was the dominant type in our survey but the four novel STs underline the high genetic diversity and unique polymorphisms inC. difficilefrom China.

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Toxin A–Negative, Toxin B–PositiveClostridium difficileInfection Diagnosed by Polymerase Chain Reaction

Cited by 5 publications

References 10 publications

Sequence Variation in tcdA and tcdB of Clostridium difficile: ST37 with Truncated tcdA Is a Potential Epidemic Strain in China

Sequence Variation in tcdA and tcdB of Clostridium difficile: ST37 with Truncated tcdA Is a Potential Epidemic Strain in China

Preliminary screening of type IV secretion system in divergent geographic sources of Clostridiumï¿½difficile

Multilocus sequence typing (MLST) analysis of 104Clostridium difficilestrains isolated from China

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