MRSA

by Bridger Buller

 

            The etiologic agent of methicillin resistant Staphylococcus aureus (MRSA)is the namesake of the MRSA, Staphylococcus aureus. (1)  MRSA is a major source of nosocomial infections.(2)  MRSA is transmitted when touching a person's skin that is infected, fomites from an infected person, unwashed cuts, and your chances of contracting MRSA is increased with abuse of antibiotics.  (3)  MRSA is found commonly in hospital patient's upper respiratory tract and bronchopulmonary tract, and consequently in hospital ventilators due their contact with patient sputum. (1)  There are two types of MRSA, hospital associated MRSA & community associated MRSA (HA MRSA & CA MRSA).  These two types have a unique genome from each other.  The common strains of HA MRSA include the US 100 and US 200 which contain a different cassette of resistance genes than the CA MRSA US 300  & US 400 strains.  The major difference is that CA MRSA contains a gene for a necrotizing cytotoxin that promotes virulence and invasiveness.  Symptoms of  MRSA are boils and abscesses that first appear like a spider bite, but can turn to an ugly infection in the skin, nose, or respiratory organs. (4)  The CDC reports that the Clinical and Laboratory Standards Institutes “recommends the cefoxitin disk screen test, the latex agglutination test for PBP2a, or a plate containing 6 μg/ml of oxacillin in Mueller-Hinton agar supplemented with NaCl (4% w/v; 0.68 mol/L) as alternative methods of testing for MRSA. “ (6)  However, within the last few days the FDA passed a new efficient way of testing for MRSA that only takes five hours and does not require specialized instruments. It is called KeyPath MRSA/MSSA Blood Culture Test is &  it's manufactured by MicroPhage Inc. of Longmont, Colorado. (5)  Methicillin is a semi-synthetic penicillin based antibiotic developed to combat resistance developed against natural penicillins by Staphylococcus, which had developed beta-lactamase and swapped it through transduction.  Resistance to methicillin, was soon developed and methicillin use was discontinued in the United States.  (7)  Treatment of MRSA is looking towards the future.  The Institute of Bioengineering and Nanotechnology has teamed up with IBM to create a polymer that recognizes MRSA and destroys it without interfering with red blood cells, the way that other polymers created for this purpose have done.  It is biodegradable and flushes out of the body when it is finished.  This nanotechnology is representative what we will see replacing antibiotic treatments in the near future.  This will have to be approved by the FDA before its use, but is an exciting prospect.  The way that MRSA is being treated now does not help the stigma of abuse of antibiotics.  It is becoming increasingly difficult to treat in this way, and relies on a huge combination of antibiotics that MRSA may or may not be developing resistance for including:Clindamycin, Daptomycin, Doxycycline, Linezolid (Zyvox), Minocycline, Tetracycline, Trimethoprim-sulfamethoxazole (Bactrim, Bactrim DS, Septra, Septra DS),Vancomycin (Vancocin, Vancoled).  This often used in conjunction with dialysis and oxygen therapy.  (9)  There is currently no vaccine for MRSA, but the ones being proposed in the last few years are being tailored to stop surgery related infections.  The University of Rochester has found a target for monoclonal antibodies called glucosaminidase that contributes to MRSA infections after bone replacement surgeries.  (10)  This is in phase I trials currently but has great potential move up the research pipeline.  This is great news, especially because the vaccine by Intercell and Merck that had made its way into human trials was halted last month. (11)  The CDC reported incidences of MRSA infections from a total population of about 42 million at  19,311,576 for 2009.  (12)  The state of Texas only has population data for select high schools and prisons, but a bill was recently passed created by the 81st legislature calling for means of collecting statewide data on emerging infectious diseases including MRSA. (13)

 

  1. Watanabe et al.. "Note: Molecular Analysis of Methicillin-Resistant Staphylococcus aureus as a Causative Agent of Bronchopulmonary Infection: Relation to Colonization in the Upper Respiratory Tract." National Center for Biotechnology Information. Version 38(10). American Society for Microbiology, 5 Nov. 2000. Web. 8 May 2011. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC87496/>.
  2. Fierobe L et. al.. "Methicillin-resistant Staphylococcus aureus as a c... [Clin Infect Dis. 1999] - PubMed result." National Center for Biotechnology Information. Version (5):1231-8.. Clin Infect Dis. , 29 Nov. 1999. Web. 8 May 2011. <http://www.ncbi.nlm.nih.gov/pubmed/10524968/>.
  3. U.S. government document no author given. "MRSA flyer." U.S. Department of Health website. South Dakota Department of Health, n.d. Web. 8 May 2011. <http://doh.sd.gov/PDF/MRSAflyer.pdf>. 
  4. Bourlag, Gwen, Jefferey Davis, and Barry Fox. "COMMUNITY ASSOCIATED METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS (CA MRSA) Guidelines for Clinical Management and Control of Transmission." Wisconsin Department of Health Services. Wisconsin Division of Public Health, n.d. Web. 8 May 2011. <www.dhs.wisconsin.gov/communicable/resources/pdffiles/CAMRSAGuide_1105.pdf>.
  5. Jefferson, Erica. "FDA Clears First Test to Quickly Diagnose and Distinguish MRSA and MSSA." U S Food and Drug Administration Home Page. 06 May 2011. Web. 08 May 2011. <http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm254512.htm>.
  6. "Laboratory Detection of Oxacillin/Methicillin-resistant Staphylococcus Aureus | CDC.gov." Centers for Disease Control and Prevention. 9 Aug. 2010. Web. 08 May 2011. <http://www.cdc.gov/mrsa/lab/lab-detection.html>.
  7. Tortora, Gerard J., Berdell R. Funke, and Christine L. Case. Microbiology: an Introduction. Tenth ed. San Francisco, CA: Pearson Benjamin Cummings, 2010. 559-61. Print.
  8. Tan, Elena, and Nidyah Sani. "IBN and IBM Co-Develop New Weapon Against Drug-Resistant Superbugs." Institute of Bioengineering and Nanotechnology. IBM, 4 Apr. 2011. Web. 8 May 2011. <http://www.ibn.a-star.edu.sg/images/cms_press/press_67.pdf>.
  9. Ron Jonk-. "MRSA - Treatment." University of Maryland Medical Center | Home. 30 May 2009. Web. 08 May 2011. <http://www.umm.edu/ency/article/007261trt.htm>.
  10. Dewhurst, Stephen. "Researchers Unzip MRSA and Discover Route for Vaccine - News Room - University of Rochester Medical Center." University of Rochester Medical Center, Rochester NY. 18 Jan. 2011. Web. 08 May 2011. <http://www.urmc.rochester.edu/news/story/index.cfm?id=3095>.
  11. Reid, Katie. "Merck, Intercell Stop Enrollment for MRSA Vaccine | Reuters." Business & Financial News, Breaking US & International News | Reuters.com. 11 Apr. 2011. Web. 08 May 2011. <http://www.reuters.com/article/2011/04/11/us-intercell-idUSTRE73A4SL20110411>.
  12. "ABC's Population Matrix." ABC's Population Matrix. CDC, 2009. Web. 08 May 2011. <http://www.cdc.gov/abcs/downloads/ABCs_pop_matrix.pdf>.
  13. "Data & Statistics." Texas Department of State Health Services. 06 May 2011. Web. 08 May 2011. <http://www.dshs.state.tx.us/idcu/health/antibiotic_resistance/mrsa/data/>.