![Figure 1. Methicillin-resistant Staphylococcus aureus bacteria (MRSA) under a scanning electron
microscope (2013) [Image] At: www.naturesalternativepdx.com (Accessed on 27/10/2015)
Figure 2. Example of a phylogenetic tree for MRSA (2008) [Image] At:
http://bioweb.uwlax.edu/bio203/s2008/seubert_heid/Classification.htm (Accessed on 27/10/2015)
Figure 3. Staph. aureus (2013) [Image] At: https://www.studyblue.com/notes/note/n/mis-study-
guide-2013-14-professor/deck/8688414 (Accessed on 27/10/2015)
Figure 4. Staph Epidermidis On Mannitol Salt Agar (2015) [Image] At: http://imageck.com/19916552-
staph-epidermidis-on-mannitol-salt-agar.html (Accessed on 27/10/2015)
Figure 5. A zone of Inhibition is evident around the oxacillin disk for S. aureus, left, but not for
Methicillin-resistant S. aureus (MRSA), right. (2006) [Image]
http://www.antimicrobialtestlaboratories.com/Zone_of_Inhibition_Test_for_Antimicrobial_Activity.ht
m (Accessed on 27/10/2015)](https://image.slidesharecdn.com/mrsa-151101194846-lva1-app6891/85/Mrsa-9-320.jpg)
![Figure 6. The Unknown Killer: MRSA (2012) [Image] At:
https://www.behance.net/gallery/3997835/Infographic (Accessed on 27/10/2015)
Figure 7. The Unknown Killer: MRSA (2012) [Image] At:
https://www.behance.net/gallery/3997835/Infographic (Accessed on 27/10/2015)](https://image.slidesharecdn.com/mrsa-151101194846-lva1-app6891/85/Mrsa-10-320.jpg)
Mrsa
- 1. MRSA METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS Figure 1. Methicillin-resistant Staphylococcus aureus bacteria (MRSA) under a scanning electron microscope
- 2. Domain Bacteria Kingdom Eubacteria Phylum Firmicutes Class Bacilli Order Baciallales Family Staphylococcaceae Genus Staphylococcus Species Staphylococcus aureus Sub Species Methicillin-resistant Staphylococcus aureus Taxonomy Figure 2. Example of a phylogenetic tree for MRSA
- 3. Structure • Gram positive spherical bacterium • Yellow in colour • Forms grape like clusters as the cell division happens in multiple planes • Has a cell wall of peptidoglycan that contains multiple glycine residues • No Flagella making the organism immobile Figure 3. Staph. aureus
- 4. Metabolism • Can uptake a number of nutrients including glucose, mannose, mannitol, sucrose, lactose and others. • Uses aerobic respiration or fermentation which produces lactic acid for energy production • Due to the production of products such as lactic acid, Mannitol Salt Agar can be used as a selective medium Figure 4. Staph Epidermidis On Mannitol Salt Agar
- 5. • MRSA is resistant to beta-lactam antibiotics due to the process of natural selection. • Resistance makes MRSA infection more difficult to treat with standard antibiotics which makes it more dangerous. • As it is frequently in contact with humans it can show resistance to a growing number of therapies. • mecA is the gene responsible for resistance to beta- lactam antibiotics Resistance to antibiotics Figure 5. A zone of Inhibition is evident around the oxacillin disk for S. aureus, left, but not for Methicillin-resistant S. aureus (MRSA), right.
- 6. MRSA evades the immune system by: • Expressing cell surface toxins • Secretes proteins that inactivate complement cascade • Bind and inactivate antibodies and reduce effectiveness • Neutrophil chemotaxisis • Inhibiting opsonisation • Neutralizing antimicrobial peptides
- 7. Why does MRSA spread easily in hospitals? MRSA is easily spread by skin to skin contact with somebody infected with the organism, as well as coming into contact with carrier material (e.g. towel) In hospitals patients are more at risk due to ◦ Weakened immune system ◦ Frequent catheter insertions ◦ Use of a ventilator Contributing factors in hospitals ◦ Overcrowding, Understaffing, movement of patients from ward to ward, Failure to discharge elderly patients back into the community Figure 6. The Unknown Killer: MRSA
- 8. • MRSA is one of the most common hospital acquired infections • In healthy humans it is an inhabitants the skin and mucous membranes in the nose • Approx. 30% of normal healthy population is infected with S. aureus as it can asymptotically colonize the skin of human hosts • If a break in the skin occurs it can allow the bacterium to enter the wound and cause an infection Figure 7. The Unknown Killer: MRSA
- 9. Figure 1. Methicillin-resistant Staphylococcus aureus bacteria (MRSA) under a scanning electron microscope (2013) [Image] At: www.naturesalternativepdx.com (Accessed on 27/10/2015) Figure 2. Example of a phylogenetic tree for MRSA (2008) [Image] At: http://bioweb.uwlax.edu/bio203/s2008/seubert_heid/Classification.htm (Accessed on 27/10/2015) Figure 3. Staph. aureus (2013) [Image] At: https://www.studyblue.com/notes/note/n/mis-study- guide-2013-14-professor/deck/8688414 (Accessed on 27/10/2015) Figure 4. Staph Epidermidis On Mannitol Salt Agar (2015) [Image] At: http://imageck.com/19916552- staph-epidermidis-on-mannitol-salt-agar.html (Accessed on 27/10/2015) Figure 5. A zone of Inhibition is evident around the oxacillin disk for S. aureus, left, but not for Methicillin-resistant S. aureus (MRSA), right. (2006) [Image] http://www.antimicrobialtestlaboratories.com/Zone_of_Inhibition_Test_for_Antimicrobial_Activity.ht m (Accessed on 27/10/2015)
- 10. Figure 6. The Unknown Killer: MRSA (2012) [Image] At: https://www.behance.net/gallery/3997835/Infographic (Accessed on 27/10/2015) Figure 7. The Unknown Killer: MRSA (2012) [Image] At: https://www.behance.net/gallery/3997835/Infographic (Accessed on 27/10/2015)