Impact of Norepinephrine on the Growth and Virulence of Clostridioides Difficile
Abstract
Clostridioides difficile infection (CDI) is considered as an urgent threat to the public by CDC, 2019. It causes life-threatening diarrhea and pseudomembranous colitis, mostly in those taking antibiotics or at the end of their antibiotic course. It is also notified as hospital-associated pathogens because one-third of the CDI has occurred in the health care center. Norepinephrine (NE) is a stress-associated neuroendocrine hormone released upon sympathetic stimulation to mediate stress. Gut walls are highly innervated by the sympathetic nervous system. During stress, elevated level of NE released in the GI tract could influence bacterial overgrowth & translocation. It is already known for its role in modulating the behavior of several bacterial pathogens such as Staphylococcus, Escherichia coli, Salmonella, and Vibrio cholera. This study aims to evaluate the effect of NE treatment on the growth and virulence of C. difficile. Here, we studied the effect of NE on six different C. difficilestrains isolated from humans. To understand the influence on growth, bacterial culture was treated (+/- )NE (5µM & 50 μM) during their log phase and recorded the density of the cell each time period for constructing the growth curve. In addition, after NE treatment, bacterial cells were taken for further analysis. For investigating the impact of NE on the virulence genes expression, a qPCR reaction was performed along with -RT / noRT control reactions for assessing the RNA sample free from genomic DNA contamination. In the case of growth, higher growth was observed in VPI 10463 at 6 hour time point only, and in strain, NR 49277 significantly stimulated after 6 hours and continued till 8 hours after treatment with 50 μM NE. In strain NR 49282, decreased growth was observed at 7-hour time points after 50 μM NE treatment. But, there was no difference in cell density between control & 5μM NE treated bacterial culture in all strains. Toxin genes (tcdA & tcdB)and flagellin gene ( fliC), were upregulated in NR 49290, NR 49277 & VPI 10463 strains in both concentrations of NE and down-regulated in NR 49282. In strain NR 32888, toxin genes were downregulated while treated with 5μM NE but upregulated after 50μM NE treatment, though fliC was downregulated in both concentrations. In strain NR 32891, tcdA was downregulated, but tcdB & fliC were upregulated after NE treatment in both concentrations. Increased expression in pilin gene, pilA1 in strain NR 49277, NR 49290, VPI 10463 & NR 32891 in both concentrations was observed. In addition, pilA3 in NR 49277, VPI 10463 & NR 32891, and PilA5 in NR 49277 & NR 49290 showed an upregulation pattern while treated with both concentrations. Modulating this response, it is possible to reduce the pathogenicity of C. difficileduring medical care & antibiotic use.
Degree
M.Sc.
Advisors
Narayanan, Purdue University.
Subject Area
Epidemiology|Endocrinology
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