Project Background

Photo of MRSA taken using Scanning Electron Micrograph 10,000x magnification

Staphylococcus aureus is a gram-positive bacterium in the genus staphylococcus. It is frequently found on the human respiratory tract and skin flora. S. aureus has a circular shape, and grows in clumps like a grape. S. aureus is not always pathogenic: it can be found on the skin a nasal flora of healthy people, and approximately 20% of the human population is thought to be a long term carrier of the bacteria*. But it can cause disease by producing toxic proteins. The diseases caused by S. aureus ranges from minor skin infections such as pimples, impetigo, and boils to life threatening disease such as pneumonia, and meningitis. Some of these S. aureus developed resistance to beta-lactam antibiotics. To determine if a given strain of S. aureus has beta-lactam antibiotic resistance, scientists often use methicillin, a beta-lactam antibiotic. Because of this, the S. aureus that has beta-lactam antibiotic resistance is called Methicillin Resistant S. aureus (MRSA) and the S. aureus that does not have beta-lactam resistance is called Methicillin Sensitive S. aureus (MSSA).

S. aureus and the disease caused by it

The beta-lactam resistance of MRSA makes it difficult to treat with conventional medicine. MRSA first appeared about 50 years earlier, and has developed into a major clinical health issue since. MRSA is highly contagious, especially in hospitals where the weakened immune system makes patients an easy target for MRSA. In fact, MRSA is thought to be one of the five most common causes of nosocomial infections**. because of these traits, MRSA is one of the most dangerous clinical problems. It was shown that simple methods such as washing hands and using sterile medical equipment led to significant improvements in nosocomial infections of MRSA (source) but that does not solve that fundamental problem of the multidrug resistance of MRSA.

2012 MRSA spread map of Europe by ECDC

2012 MRSA spread graph of Europe by ECDC

* Kluytmans J, van Belkum A, Verbrugh H (July 1997). "Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks". Clin. Microbiol. Rev. 10 (3): 505–20. PMC 172932. PMID 9227864.

** Bowersox, John (27 May 1999). "Experimental Staph Vaccine Broadly Protective in Animal Studies". NIH. Archived from the original on 5 May 2007. Retrieved 28 July 2007.