A comparison of the dominant strains of Clostridium difficile in Scotland: growth rate, toxin production and sporulation
Abstract number: P675
Objectives: To determine the differences in potential virulence of Clostridium difficile ribotypes most prevalent in Scotland (106, 001 and 027) using phenotypic traits and genomic analysis.
Methods: The growth of C. difficile ribotypes 106, 001 and 027 was observed along with 2 reference strains, 630 and VPI10463, over a 24 h period by measurement of OD600 every 4 h. Corresponding toxin production was studied by ELISA using the C. difficile TOX A/B II kit (Techlab) and associated spore production was determined by viable counts for the same time points. The expression of the genes coding for the C. difficile toxins, tcdA and tcdB, and the initiator of sporulation, spo0A, was analysed by Real-Time RT-PCR.
Results: The growth of all ribotypes was similar, but 106 and 001 appeared to have accelerated growth at 4 h compared to 027. Toxin production was markedly different between the strains. By the stationary phase, 027 produced at least 10-fold more total toxin (A and B) than the others. 106 produced the most spores during the stationary phase, followed by 027 and 001. Transcriptional analysis revealed that tcdA expression was the highest in 027, almost double that observed in 106 and 001, but that of tcdB was markedly higher in 106. spo0A transcription was the highest in 001, followed by 027 and 106.
Conclusions: Ribotypes 106, 001 and 027 are currently the most prevalent in Scotland. The growth of these strains demonstrates that greater cell numbers do not contribute to greater virulence. However, higher spore production, as seen in 106, 001 and 027, is significant in terms of spread in the environment. Large amounts of toxin production, however, can lead to greater virulence, as seen in 027 and even in 106 and 001 that do not produce as much toxin as 027, but produce significantly more toxin than reference strain 630. It is of interest to note that in 027, tcdA transcription was significantly higher than that of tcdB. This was also observed in 001 and 106, though not as prominently. This suggests that even though toxin B is essential for virulence, production of larger amounts of toxin A may increase virulence. spo0A transcription was also higher in the epidemic strains and this is also a good indicator of differences between the strains. The epidemic ribotypes 106, 001 and 027, therefore, appear to have increased potential to spread in the environment and cause more severe disease.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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