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

AIM

This study aimed to evaluate the expression of A, B, and binary toxin genes (A and B) by Real-Time PCR and molecular typing of isolated from patient diarrhea samples from Hamadan Hospitals, west of Iran.

BACKGROUND

The concentration of 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 infection (CDI).

METHODS

From November 2018 to September 2019, 130 diarrhea samples were collected from hospitalized patients in three hospitals in Hamadan. 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 . Genes encoding A and B were detected in all isolates, and 8 (50%) and 6 (37.5%) isolates were positive for the A and B genes. Real-time PCR results showed different expression levels of the toxin genes. A significant increase in the expression of the A gene was observed compared with the control strain (P<0.05). Besides, more expression of A gene was observed in the strains compared with B gene. Ribotyping and rep-PCR results showed high genetic diversity of among hospitals investigated.

CONCLUSION

We encountered toxigenic 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.