Comparison of toxin gene expression levels and molecular typing of Clostridioides difficile strains isolated from patients with diarrhea.

Aim: This study aimed to evaluate the expression of tcd A, tcd B, and binary toxin genes ( cdt A and cdt B) by Real-Time PCR and molecular typing of Clostridioides difficile isolated from patient diarrhea samples from Hamadan Hospitals, west of Iran.
Background: The concentration of C. difficile toxins (CDTs) is associated with the severity of the disease and the mortality rate. Measuring CDT levels could provide a reliable and objective means of determining the severity of C. difficile infection (CDI).
Methods: From November 2018 to September 2019, 130 diarrhea samples were collected from hospitalized patients in three hospitals in Hamadan. C. difficle isolates were detected by culture and PCR. The presence of the genes encoding the toxin was identified by PCR, whereas the measurement of toxin expression was conducted using a relative Real-Time PCR technique. Genetic linkage of the isolates was also assessed by Ribotyping and Repetitive Extragenic Palindromic (rep-PCR) methods.
Results: Among 130 diarrhea samples, 16 (12.3%) were positive for C. difficile . Genes encoding cdt A and tcd B were detected in all isolates, and 8 (50%) and 6 (37.5%) isolates were positive for the cdt A and cdt B genes. Real-time PCR results showed different expression levels of the toxin genes. A significant increase in the expression of the tcd A gene was observed compared with the control strain (P<0.05). Besides, more expression of cdt A gene was observed in the strains compared with cdt B gene. Ribotyping and rep-PCR results showed high genetic diversity of C. difficile among hospitals investigated.
Conclusion: We encountered toxigenic C. difficile strains with various toxin expression levels, ribotypes, and rep types based on the findings of this study. This indicated that various clones from various sources circulate in the hospitals and among patients.
Competing Interests: The authors declare that they have no competing interests.
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