Novel Clade C-I Clostridium difficile strains escape diagnostic tests, differ in pathogenicity potential and carry toxins on extrachromosomal elements
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Date
2018Author
Ramírez Vargas, Gabriel
López Ureña, Diana
Badilla Lobo, Adriana
Orozco Aguilar, Josué
Murillo Corrales, Tatiana
Rojas, Priscilla
Riedel, Thomas
Overmann, Jörg
González, Gabriel
Chaves Olarte, Esteban
Quesada Gómez, Carlos
Rodríguez Sánchez, César
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The population structure of Clostridium difficile currently comprises eight major genomic clades. For the highly divergent C-I clade, only two toxigenic strains have been reported, which lack the tcdA and tcdC genes and carry a complete locus for the binary toxin (CDT) next to an atypical TcdB monotoxin pathogenicity locus (PaLoc). As part of a routine surveillance of C. difficile in stool samples from diarrheic human patients, we discovered three isolates that consistently gave negative results in a PCR-based screening for tcdC. Through phenotypic assays, whole-genome sequencing, experiments in cell cultures, and infection biomodels we show that these three isolates (i) escape common laboratory diagnostic procedures, (ii) represent new ribotypes, PFGE-types, and sequence types within the Clade C-I, (iii) carry chromosomal or plasmidal TcdBs that induce classical or variant cytopathic effects (CPE), and (iv) cause different levels of cytotoxicity and hamster mortality rates. These results show that new strains of C. difficile can be detected by more refined techniques and raise questions on the origin, evolution, and distribution of the toxin loci of C. difficile and the mechanisms by which this emerging pathogen causes disease.
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10.1038/s41598-018-32390-6Collections
- Microbiología [1171]