Life Sciences students

Cynthia D. Grady

Cynthia D. Grady

Previous Research Experience: Summer Research Opportunity Program, Duke University
Program Dates: May 28 - August 4, 2007

Research Advisor: Dr. Patrick C. Seed, MD, PhD
Research Abstract:

Determining the Prevalence of the Fim Recombinases in Escherichia coli: Regulators of the Preeminent Virulence Determinant, Type I Pili

Cynthia D. Grady, Patrick Seed, M.D., Ph.D.
Department of Pediatrics, Department of Molecular Genetics and Microbiology
Duke University Medical Center, Durham, NC 27710.

Uropathogenic Escherichia coli (UPEC), the main cause of urinary tract infections, produces type 1 pili to attach to and penetrate into the bladder epithelium, thus initiating cystitis. In UPEC and commensal E. coli, type 1 pili are regulated by phase variation via combinations of five homologous, unlinked Fim recombinases but their combined prevalence in strains of different environmental origins is undetermined. We predicted that FimX, IpuA, and IpuB are more prevalent in UPEC than commensal strains, while FimB and FimE are common to most E. coli. Using genomic DNA from clinical and commensal E. coli, a multiplex PCR assay was developed for the detection of the five known Fim recombinase genes. The assay was applied to genomic DNA from 75 and 69 UPEC and commensal isolates, respectively. Among UPEC, 25.3% had all 5 Fim recombinase genes, 69.3% carried the combination fimB, fimE,and fimX, 4% had only fimB and fimE. One UPEC strain carried fimB, fimE, fimX, and ipuA. Of the commensal strains, 9.3% had all 5 Fim recombinases, 55.6% exclusively carried the genes fimB and fimE, 20.4% had only fimB, fimE,and fimX, 11.1% had just fimB, fimE, IpuA and IpuB, One strain had fimB, fimX, IpuA and IpuB, and 1 strain had fimB, fimE, fimX, and IpuB. These data demonstrate that fimX, ipuA, and ipuB are more prevalent in UPEC than commensal E. coli and that these recombinases may be evolutionarily conserved among UPEC to promote niche-specific regulation of type 1 pili.

Programs applied to for upcoming summer 2008:

Accepted into the University of Arizona Minority Health Disparities Summer Research Opportunity Program.  

  • University of Alabama at Birmingham Minority Health International Research Training (MHIRT) Program
  • University of Michigan Health Management and Policy Summer Enrichment Program
  • San Diego State University MHIRT Program
  • John's Hopkins Diversity Summer Internship Program
  • Morehouse School of Medicine Public Health Summer Fellows Program

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