Purdue University Graduate School
Thesis_Sharmin_CPB.pdf (1.06 MB)


Download (1.06 MB)
posted on 2022-04-29, 19:14 authored by Kamrun Naher SharminKamrun Naher Sharmin

Clostridioides difficileinfection  (CDI)  is  considered  as  an  urgent  threat  to  the  publicby  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 notifiedas hospital-associated pathogensbecause one-third  of  the CDIhas occurredinthe 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  tractcould  influence  bacterial  overgrowth  &  translocation.  It  isalready known  for  its  role  in  modulating  the  behavior  of  several  bacterial  pathogens  suchas 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  understandthe  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 assessingthe  RNA  sample  free  from  genomic  DNA  contamination.  In the case of growth,higher growth was observed in VPI 10463at 6 hourtime pointonly,and in strain,NR 49277 significantly stimulated after 6 hoursand continued till 8 hours after treatmentwith50μM NE. In strain NR 49282, decreasedgrowth was observed at7-hourtime pointsafter 50 μM NEtreatment.But, there was no difference in cell density between control &  5μM NE treated bacterial culture in all strains.

Toxingenes(tcdA&tcdB)and flagellin gene(fliC),were upregulated in NR 49290, NR 49277 & VPI 10463strains in both concentrations of NE and down-regulated in NR 49282.In strain NR 32888, toxin genes were downregulated while treated with 5μM NEbut upregulated after 50μM NEtreatment, though fliC was downregulated in both concentrations. In strain NR 32891,  tcdAwas downregulated,but tcdB& fliCwere upregulatedafter NE treatmentin both concentrations. Increased expression in pilin gene,pilA1in strain NR 49277, NR 49290, VPI 10463& NR 32891 in both concentrationswas observed.  In addition, pilA3in NR 49277, VPI 10463& NR 32891 and PilA5in  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 Type

  • Master of Science


  • Comparative Pathobiology

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Sanjeev Narayanan

Additional Committee Member 2

Hyunwoo Lee

Additional Committee Member 3

Deepti Pillai

Usage metrics