1. How did this dangerous bacterial strain evolve?
Chapter 9
Question 6:
Last semester, several students at CCRI were hospitalized with potentially life-threatening MRSA infections.
What is MRSA?
How did this dangerous bacterial strain evolve?
Explain.
Carl Tuoni Beth Miller
Silvio Penta

2. What is MRSA and its Signs and Symptoms
Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by Staphylococcus aureus bacteria, often called "staph.”
Staph or MRSA infections usually start as small red bumps that resemble pimples, boils or spider bites. These can swiftly turn into deep, sore abscesses that require surgical draining. Sometimes the bacteria remain restricted to the skin. But they can also burrow deep into the body, causing potentially life-threatening infections in bones, joints, surgical wounds, the bloodstream, heart valves and lungs.

3. Photo courtesy: The Mayo Clinic
Staph skin infections often start out as small red bumps (right) and then turn into deep abscesses (left.)
Photo courtesy: The Mayo Clinic

4. Advanced MRSA Infection

5. In 2005, according to CDC reports more people died from MRSA than AIDS
In 2005, according to CDC reports more people died from MRSA than AIDS. Most of these infections were contracted in a healthcare setting.

6. Causes
MSRA is the result of decades of excessive and unnecessary antibiotic use
Antibiotics that have been prescribed for colds, flu, and other viral infections that do not respond to these drugs
Antibiotics found in food and water, antibiotics can be found in beef, pigs and chickens
Even antibiotics that are used correctly they can contribute to the rise of drug-resistant bacteria

7. Some Common Examples:
1) You have a sore throat and go to the dr. he gives you an antibiotic called Augmentin because it is strep throat. Even though the dr. told you to finish all of the medication, you feel better and stop taking it after 5 days.
2) You have a sore throat again, you have had strep before and still have about half of that bottle of Augmentin you did not finish last time. So you decide to take the other half. Only this time the medicine doesn’t work. You have created a strain of strep at least in your own body, which can no longer be fought with Augmentin. Had you finished the medicine the first time not only would you not have gotten it again so soon, but if you did get it agian the Augmentin would have worked again.

8. Discovery, History & Evolution
First identified in 1961 in the UK, MRSA was referred to in the press as “the superbug” because it resisted the broad spectrum of beta lactin (a natural antibiotic produced by fungi) derived antibiotics.
Through the process of natural selection, the more resistant mutants of the species became more prevalent, as the drug vulnerable strain died.
There is no question that MRSA evolved in the hospital setting. No one knows for sure how MRSA evolved into the community known as CA-MRSA. It did not however derive from the hospital strain. The theory that makes the most sense is that due to the over use of antibiotics, a stronger, more resistant bacteria evolved.

9. One Third of the population are carrying the infection
Normally found on the skin or in the nose of around one third of the population
People carrying staph are said to be colonized but not infected with MRSA
Healthy people can be colonized with MRSA and have no ill effects, however they can pass the germ to others

10. Staph is generally harmless
Staph bacteria are generally harmless unless they enter the body through a cut
Only causes minor skin problems in healthy people
Staph infection may cause serious illness in older adults, or people who are ill, or have weakened immune systems

11. The “Super-bug Hype”
As serious as MRSA is, it has been around for a long time, look at the graph below and you will see that the incidence of the infection has not gone up much from 2001, yet from it was in the news much more than earlier in the decade.

12. Risk factors for (HA) MRSA Include
Because hospital and community strains of MRSA generally occur in different settings the risk factors for the two strains differ
Risk factors for (HA) MRSA Include
Current or recent hospitalization- MRSA is a concern among hospitals where it can attack those most vulnerable
Residing in a long term care facility- MRSA is far more prevalent in these facilities than in hospitals
Invasive devices- People who are on dialysis, are catheterized, have feeding tubes, or other invasive devices are at a higher risk
Recent antibiotic use

13. Risk factors for community acquired (CA) MRSA
Young Age- CA-MRSA can be particularly dangerous in children often entering the body through a cut or a scrape. Their immune system may not be fully developed
Participating in contact sports- the bacteria spread easily thro
ugh cuts and abrasions and skin to skin contact.
Sharing towels or athletic equipment- CA-MRSA has spread among athletes sharing razors, towels, uniforms, or equipment

14. Having a weakened immune system- People with a weakened immune system are more likely to have severe CA-MRSA infections
Living in crowded or unsanitary conditions- Outbreaks of CA-MRSA have occurred in military training camps and in prisons
Association with health care workers- People who are in close contact with health care workers are at serious risk of infections.

15. Prevention is the Best Medicine
Avoid contact with the wounds or bandages of others
Keep personal items personal . Avoid sharing towels, razors, clothing, and athletic equipment
Keep wounds covered. Keep cuts and abrasions clean and covered with sterile dry bandages until they heal
Shower after athletic games or practices
Sanitize linens if you have a cut or sore wash towels and bed linens in a washing machine using hot water. Wash gym and athletic clothes after each wearing