Kyle's Interview with Drs. Sydney and Yang,
Infectious Disease Specialists
Q: What is the origin of MRSA?
A: MRSA developed soon after antibiotics were invented. Within a couple of years after antibiotics were discovered, some hospitals began seeing MRSA infections.
Q: Is MRSA an epidemic?
A: I would consider MRSA an epidemic. It started to emerge in the 1980s. It was rare until the 1990s when it became more common.
Q: How bad is the problem/epidemic?
A: The problem is bad. There are two different kinds of MRSA. The first kind began in the hospital. The second comes from the community, is more aggressive, but is susceptible to more antibiotics. It's costing a lot of money (associated with morbidity, mortality). People can become seriously ill and/or die. We don't have a good way of keeping people from getting sick. When they do become infected, we have good ways of treating them. However, we are losing these "good ways".
Q: How has it been spreading?
A: MRSA lives in our skin and nose. It is able to survive for a long period of time and can spread from towel to towel, exercise machines to skin, spread in hospital from hands of health care workers, etc.
Q: How are MRSA strains different?
A: There are two MRSA strains. Hospital strains are like knights, protected in armor but unable to move and attack that well. Community-acquired MRSA is lightly armored, quicker, and more fatal. It carries a protein that is responsible for a lot of complications we see. It also tends to cause more harm.
Q: Is any strain more dangerous or resistant to antibiotics?
A: While people do die of nosocomial MRSA, community-acquired MRSA causes proportionally more deaths because it is more common and more aggressive. Most community-acquired MRSA infections are mild but some can cause serious problems.
Q: What is the difference in structure?
A: There's a cassette - a sequence of genes on a chunk of DNA that inserts itself on the genes. There are four kind of this cassette "SCC". What is encoded is the key. Some scientists think that toxins are encoded on it. Community-acquired MRSA have one typical SCC mecA gene. It's a complex issue.
Q: How do antibiotics affect MRSA?
A: Most antibiotics have either no effect on MRSA,or are able to kill it. Some researchers think antibiotics cause MRSA to become more virulent. When we isolate MRSA, we do sensitivity testing. After that, we choose antibiotics based on the results. Antibiotics work by different mechanisms. They can break down cell wall or inhibit protein synthesis. We distinguish antibiotics that kill (bactericidal) and ones that stop (bacteriostatic) to let our body do the killing. CA-MRSA seems to be more aggressive than regular Staph. A special toxin protein called PVL can be found in regular Staph, but almost all community-acquired MRSA carry PVL.
Q: What antibiotics are best used to treat it, and why?
A: For mild infections, for example, pimples, it might be best to watch it, especially for a healthy host. Your defense mechanism might be sufficient. But if you are weak, e.g., have diabetes and are on dialysis, then you can have a serious infection, and you will want to use a strong antibiotic, e.g., Vancomycin. There are many choices, but there are limitations also. Some antibiotics don't get delivered to certain body parts. It's not a one-size-fits-all. Not all of the damage is done by the toxin. Sometimes we want to stop protein synthesis, which is important to stop toxin production. Clindamycin and Linolezoid can weaken the bacteria, so the host can kill the bacteria. The problem with Vancomycin is that it doesn't kill MRSA well. If we have Methicillin-sensitive Staph, we would never use Vancomycin. We don't have many choices that kill MRSA well. Rifampin kills it well, but Staph develops resistance quickly, so we use it with another antibiotic to protect Rifampin. Bactrim is also a good antibiotic for an outpatient. The choice depends on the situation, severity, and setting (in or out of the hospital).
Q: What do you think MRSA will be like in the future?
A: Unless we get a vaccine, it will be an arms race. It's always been an arms race. It develops resistance as we develop new antibiotics. Scary thing is that it's now in the community. It also causes psychological stress. There are families that are ravaged by infections, not knowing if the infection will be serious.
Q: Do you think that there will ever be an antibiotic that works on every infection?
A: No. Bacteria will always develop resistance. Now, we have drugs that work. The longer we use antibiotics, the higher the chance of developing resistance. It's not a matter of whether they will, it's a matter of when. There are already reported cases of MRSA resistant to Vancomycin.
Hygiene is the best defense we know. Bathe regularly. Minimize exchange of contaminator vectors, e.g., not sharing towels. How extreme do you want to protect yourself in exchange to how to live your life? To prevent infection, consider two areas:
1.Colonization: meaning preventing it from living on your skin or mucosa. This causes no harm to you. We carry billions of bacteria and usually there is no problem. It's when we get weak, we can get sick. It's not practical.
2.Infection: This is more important. Keep yourself healthy. Keep skin healthy and watch for skin breaks, then seek treatment if they get worse. "Don't pop boils!" Bacteria may get into blood and set up shop in the body.
Bactroban and Chlorhexidine are effective in getting rid of colonization. Shower with Chlorhexidine and apply Bactroban to nares for 3-5 days. It's sometimes coupled with oral antibiotics. It needs to be done with all household members at same time. In New Zealand where Bactroban is used a lot, 75% of Staph is MRSA, so that option is closing.