Abstract
Probiotics are widely used in the prevention of Clostridioides difficile infection (CDI). The precise dosage of probiotics is a challenge. In this study, Clostridioides difficile ATCC 9689 (CD) was exposed to different doses of Bifidobacterium breve (YH68). A transcriptomic analysis was performed on CD cells that were separately exposed to low or high doses of YH68 cell-free culture supernatant (CFCS; CDL; or CDH, respectively). The results showed that the inhibitory effect of YH68 (cell pellets or CFCS) on the growth and the damage to the cell membrane integrity of CD exhibited a dose-response relationship at the physiological level. At the transcriptional level, a large number of differentially expressed genes (DEGs) were concentrated in amino acid, carbohydrate, energy metabolism and membrane transport in CDL and CDH cells, suggesting that both doses of YH68-CFCS triggered a significant change in activities in these metabolic pathways. Importantly, a significant stimulation or suppression was found in the pathogenic pathways (quorum sensing, signal transduction, flagellar assembly, biofilm formation, and drug resistance) of CDL and CDH cells, whereas there were some differences between the two doses. For example, the expression levels of genes related to quorum sensing and signal transduction in CDH cells were suppressed significantly, whereas genes encoding toxin production and sporulation factors were enhanced; in CDL cells, the expression levels of genes associated with flagellar assembly and biofilm formation were suppressed, whereas genes associated with drug resistance were upregulated significantly. These results indicated that the inhibitory effect of YH68-CFCS against CD, especially in pathogenic and metabolic aspects, did not demonstrate a dose-response relationship at the transcriptional level.
Highlights
Clostridioides difficile is a Gram positive obligate anaerobic bacteria that can produce spores (Gil et al, 2017)
With regard to prevention, both YH68-cell and YH68-cell-free culture supernatant (CFCS) exerted a prominent preventive effect, and all the inhibitory rates of YH68 at different doses against C. difficile ATCC 9689 (CD) reached more than 50%
The inhibitory rates of YH68-cell at different doses against CD were not prominent for the therapeutic inhibition aspect, including the highest dose of YH68-cell (14.45%); the inhibitory effect of YH68-CFCS was relatively outstanding, the inhibitory rates of YH68-CFCS at different doses against CD were lower than 50%, except for that of 9-YH68CFCS (65.24%)
Summary
Clostridioides difficile is a Gram positive obligate anaerobic bacteria that can produce spores (Gil et al, 2017). Probiotics have often been used in the treatment of various clinical diseases due to their outstanding antibacterial activity with very few side effects (Rondanelli et al, 2017). A growing body of studies has shown that probiotics protect or rebuild the normal microbial community structure in the gut and activate the immune system (Goldenberg et al, 2018). Probiotics have frequently been used as adjuvant agents in clinical treatment (Sanders et al, 2019), and their high safety in the public mind has remained unchanged. The most probable reason behind this trust is that probiotics are not traditional medicines (such as antibiotics), and most of them have exerted no side effects in the vast majority of clinical CDI treatments. Considering the demand and development of precision medicine, additional attention should be focused on the precise dosage of personalized probiotic strains used in the treatment of specific diseases (Suez et al, 2019), such as CDI
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