S-STEM Scholar Brenda Arvizu's Blog: Enterococcus faecalis

Enterococcus faecalis is a gram-positive opportunistic pathogen that generally causes urinary tract infections, wound infections and a variety of nosocomial (originate in a hospital) infections. To better see this bacteria, the first image shown below shows a Scanning Electron Micrograph (SEM) of it. Through fecal contamination, this bacteria is commonly found in food, sewage, water and soil (Paulsen, 2003). In other words, it can be found in a variety of materials we come into contact everyday. In addition, E. faecalis is able to withstand “oxidative stress, desiccation, and extremes of temperature and pH, and it has high endogenous resistance to salinity, bile acids, detergents, and antimicrobials” (Paulsen, 2003). Because of this, it has acquired “intrinsic resistance to many antibiotics and a remarkable capacity for developing resistance to others” and “now ranks among the most troublesome hospital pathogens” (Phillips, 1995). For example, E. faecalis has become resistant to vancomycin. The bacteria's genome carries its ability for resistance, which is shown below in the second image. As a result of its resistance, this bacteria “persist[s] in the hospital environment and survive[s] many host defenses” (McBride, 2007). Not only has it become resistant to various antibiotics and antimicrobial agents but it produces a two-subunit toxin, also known as cytolysin; this toxin is active against eukaryotic and prokaryotic cells. With the production of cytolysin, this bacteria is able “to actively probe the environment for target cells, and when target cells are detected, allows the organism to express high levels of cytolysin in response” (Coburn, 2004). However, this toxin is not the only material produced by E. faecalis, it also creates a “gelatinase, enterococcal surface protein Esp, aggregation substance, a hyaluronidase, and a bile salt hydrolase”, which are “known or suspected of enhancing the virulence” of this bacteria. (McBride, 2007).

Unfortunately, due to how complex this bacteria is, knowledge as to how it causes diseases and “transfer[s] antibiotic resistance to other pathogens” is limited (Nallapareddy, 2005). Therefore, because of its complexity, expanding knowledge on Enterococcus faecalis is evidently necessary and critical. In other words, being able to “characterize the genetic background of a [E. faecalis] strain makes possible the study of the flow of mobile elements within the species” (McBride, 2007). Being able to successfully accomplish this will “define the diversity of the E. faecalis species and to determine the core genome content” (McBride, 2007). With this, pharmaceutical scientists will be able to develop or improve drugs currently used on this bacteria and, thus, allow affected individuals to recover quickly and more efficiently.

Through DNA extractions of Enterococcus faecalis, identifying it, diagnosing infections and progressing in drugs will easily be achieved. Hence, in an attempt to quickly, successfully and effectively identify E. faecalis, four different DNA extraction protocols will be performed. These methods will determine which one is successful in yielding the most amount of DNA. The DNA extraction protocols are as follows: QuickExtract Bacterial DNA Extraction Kit, boiling method, microwave method and enzymatic digestion followed by heating method. These four procedures will be compared to a commercially produced kit. It is hypothesized that the boiling method will yield the most amount of DNA in Enterococcus faecalis. Following the boiling method, it is expected that the procedure to produce the second highest amount of DNA in E. faecalis will be the enzymatic digestion followed by heating. Lastly, the microwave method is expected to yield the least amount of DNA of this bacteria. In order to determine the quantity of DNA yielded from each extraction protocol, nanodrop spectrophotometry and electrophoresis will be performed.

Sources

Ahmed, O., Asghar, A., & Elhassan, M. (2014). African Journal of Microbiology Research. Comparison of three DNA extraction methods for polymerase chain reaction (PCR) analysis of bacterial genomic DNA. Retrieved February 23, 2017, from http://www.academicjournals.org/article/article1391446214_Ahmed%20et%20al.pdf

Coburn, P. S. (2004). Biography in Context. Enterococcus faecalis senses target cells and in response expresses cytolysin, 306. Retrieved March 23, 2017.

Dashti, A., Jadaon, M., Abdulsamad, A., & Dashti, H. (2009). Heat Treatment of Bacteria: A Simple Method of DNA Extraction for Molecular Techniques. Kuwait Medical Journal. Retrieved from https://www.researchgate.net/publication/266888615_Heat_Treatment_of_Bacteria_A_Simple_Method_of_DNA_Extraction_for_Molecular_Techniques

Englen, M., & Kelley, L. (2000). Letters in Applied Microbiology . A rapid DNA isolation procedure for the identification of Campylobacter jejuni by the polymerase chain reaction. Retrieved February 23, 2017, from http://onlinelibrary.wiley.com/store/10.1046/j.1365-2672.2000.00841.x/asset/j.1365-2672.2000.00841.x.pdf?v=1&t=izj0lngs&s=ffc6e6e746158600322301279b959afb27079119

Epicentre. (2012). QuickExtract™ Bacterial DNA Extraction Kit. Retrieved February 28, 2017, from http://www.epibio.com/docs/default-source/protocols/quickextract-bacterial-dna-extraction-kit.pdf?sfvrsn=8

McBride, S., Fischetti, V., LeBlanc, D., Moellering, R., & Gilmore, M. (2007). PLOS One. Genetic Diversity among Enterococcus faecalis. doi:10.1371/journal.pone.0000582

Nallapareddy, S., Wenxiang, H., Weinstock, G. M., & Murray, B. E. (2005). Journal of Bacteriology. Molecular Characterization of a Widespread, Pathogenic, and Antibiotic Resistance-Receptive Enterococcus faecalis Lineage and Dissemination of Its Putative Pathogenicity Island. Retrieved March 23, 2017.

Oliveira, C. F., Paim, T. G., Reiter, K. C., Rieger, A., & D'azevedo, P. A. (2014, Jan. & feb.). Evaluation of four different DNA extraction methods in coagulase-negative staphylococci clinical isolates. Retrieved February 23, 2017, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085835/

Paulsen, T., Banerjei, L., & Myers, G. S. (2003). Science. Role of Mobile DNA in the Evolution of Vancomycin-Resistant Enterococcus faecalis. doi:10.1126/science.1080613

Phillips, D. M., Ph.D. (1995). Images in Clinical Medicine (K. Eagle M.D., Ed.). Enterococcus faecalis. doi:10.1056/NEJM199501053320105