MRSA Orthopaedic Infections

Dr. Sechrest: Hello, I’m Dr. Randale Sechrest, your host for eOrthopod.TV. Today I have as a guest,

Dr. George Risi. Dr. Risi is an infectious disease specialist. Good afternoon, Dr. Risi.

Dr. George Risi: Good afternoon. Thanks for having me.

Dr. Sechrest: Thanks for coming. What I thought we would do today is discuss a fairly common infection these days that people have heard about in the news called MRSA (methicillin resistant staphylococcus aureus). Primarily what I’m interested in doing is discussing this in the context of orthopaedic surgery because orthopaedic surgeons are real concerned about this infection and I think patients are real concerned about the infection as well. So if you would, what is MRSA (methicillin resistant staphaureus)?

Dr. George Risi: So MRSA is new strain of a common organism that we’ve dealt ever since recorded history: staphylococcus aureus or staphaureus. MRSA stands for methicillin resistant staphaureus. Ever since we started using antibiotics, bacteria have become very adept at becoming resistant to different of strains of antibiotics that we’re using. So MRSA now is a strain of bacteria that is resistant to most of the commonly used antibiotics that we use today. It has become really a big problem, especially in the United States, as the result of the emergence of strains of this organism that can cause serious illness even in otherwise healthy people, and unless people are attuned into thinking about this as clinicians, the possibility is that an antibiotic will be started, until you know the result of your culture, that will not be active against these strains of MRSA.

Dr. Sechrest: So what you’re saying is that this organism has been around. This is a typical organism that we’ve had for years.

Dr. George Risi: That’s right.

Dr. Sechrest: The staphylococcus causes a lot of skin infections, a lot of wound infections, those sorts of things. In some ways, just the common boil or the abscess normally is caused by staphaureus.

Dr. George Risi: That’s right. Staphaureus is an organism that causes the majority of boils, abscesses, etc., as well as surgical wound infections and for orthopaedic surgeons, in particular, it is the organism that we’ve known about and worry about the most over the years. So the big difference now is that there are strains of staphaureus that are now resistant to things like Ancef, Cephazolin, Penicillin, Nafcillin, the drugs that we commonly think of as being able to be used to fight off these kinds of infections. These strains of MRSA are resistant to them, and there is only a very limited of antibiotics that have clinical usefulness against them.

Dr. Sechrest: Now the name – methicillin resistant staphaureus – why did it get the name methicillin resistant? What does that refer to?

Dr. George Risi: Well, methicillin was one of the very first antibiotics that was invented or developed to combat the strains of staphaureus that were resistant to penicillin. Remember in the 1940s when penicillin came around, virtually all the strains of staphaureus were sensitive to that. But over the course of actually very few years, strains began to develop that were able to elaborate an enzyme called penicillinase, and that enzyme was able to break penicillin into a useless compound. So methicillin was one of the very first compounds that was develop to overcome this problem and still give good activity against staphaureus. Now, we don’t use methicillin anymore in clinical medicine because it does have toxicities. But in the laboratory setting, methicillin is a very commonly used antibiotic to test in the test tube if a strain of staphylococcus is resistant or not. So methicillin resistance is a laboratory-based definition, but what we know as clinicians is that when you see that term, MRSA, we know that most of the commonly used drugs against staph infections are also not going to be able to be used. Basically, all of the beta lactam antibiotics, the antibiotics that are based on penicillin or Cephazolin, none of them are going to be active against strains of MRSA.

Dr. Sechrest: Now a lot of people here the term that there’s methicillin resistant, or there’s MRSA in this hospital or that hospital and the hospital becomes infected with MRSA, or at least that’s the common utilization of that term. Can you explain that? How does methicillin get into a hospital? Is that realistic and is this something that people should be concerned with?

Dr. George Risi: There’s an awful lot of confusion about this topic. To back up of a moment, we now have, in the past couple of years, seen the emergence of two different kinds of MRSA, if you will. One is the more traditional, hospital-acquired MRSA, and the other is now this new community-acquired strain of MRSA. The community-acquired strain is the one that’s actually more worrisome because it’s the one that is even more virulent or more aggressive than conventional strains of staphaureus, and can cause illness even in otherwise totally healthy people. But when you talk about the hospital-acquired strains, it turns out that most of those strains are actually acquired in other places like extended care facilities or dialysis units, etc. These organisms tend to attack people who are compromised in some way. Either they’re very elderly or they are on dialysis or they have diabetes or they have other chronic medical conditions. So those institutions that have a lot of people with those kinds of risk factors, tend to have more of a problem with this old-fashioned kind of MRSA. But most hospitals are not uniquely susceptible so it’s very uncommon in an American hospital, and I can’t speak for hospitals in the third world, for instance. But for an American hospital to be labeled as being one that has MRSA in it, compared to a competitor hospital, that’s really just not accurate.

Dr. Sechrest: So all hospitals have MRSA or have the possibility of harboring some degree of MRSA?

Dr. George Risi: That’s right. That’s right. And if you look at, especially patients who are admitted to the Intensive Care Units of hospitals, the staph infections that happen in those hospital, about 70% of them are caused by MRSA, and that is independent of whatever you’re at. So it’s a problem that sometimes is brought into the hospital by that individual who is chronically ill and probably is carrying this organism, especially in the nose, in the nares, which is the reservoir for carriage of many of these strains.

Dr. Sechrest: Now you talked about the community acquired MRSA and you said that that’s a relatively new finding, that we’re starting to see it just come in from the community. Is that people who show up who’ve never been in the hospital and they’re harboring this organism? Is that what you’re talking about?

Dr. George Risi: That’s right. We know that staphaureus is an organism that is present in the environment, and an awful lot of people will carry it, even people who are totally healthy. What’s happened in the last few years is that the garden variety strains of staphaureus have been out-competed by these new strains, such that many people are now carrying this aggressive strain of staphaureus even though they are not necessarily members of any kind of a high risk group. Now it did originate in some people who are either institutionalized or engaged in some kinds of activities that put them at high risk for sharing of organisms. So in the prison populations, for instance, or in competitive sports teams where there’s an awful lot of contact, football especially, are places where an organism is introduced and then it’s spread very easily amongst people. But the bottom line is these are people who otherwise would not have an infection who are healthy, who are not diabetics, are not people who inject drugs, on dialysis, etc., and now this new strain of community-acquired MRSA is able to cause disease in these people who otherwise wouldn’t have had disease at all.

Dr. Sechrest: You mentioned that MRSA is just a normal staphaureus organism that has somehow evolved.

Dr. George Risi: That’s right.

Dr. Sechrest: And I think you implied that part of the reason these organisms have evolved is our utilization of antibiotics. We begin to treat different infections with antibiotics and over a period of time the organisms developed some resistance to that and then all of the sudden, now, more and more of the organism, that strain develops and is able to survive and in some ways, just evolution, that strain becomes more and more predominant. Is that accurate?

Dr. George Risi: That explains a big part of what’s going on with this. The other big part is cross talk between different strains of bacteria. We now know that within the microbial world, different strains of bacteria can actually exchange genetic information such that resistance traits that are carried on a different strand of bacteria can be transferred to a new strain and we know that the old varieties of staphaureus have acquired of their virulence traits and some of their resistance traits from other species of bacteria as well. So it’s this combination of cross talk, genetic information exchange, and then overuse of antibiotics that has led to this situation that we find ourselves in. We know that antibiotics are going to select for resistant strains because bacteria can mutate so quickly and if antibiotics are used overly much then that’s just going to speed the process even more.

Dr. Sechrest: Well, let’s talk a little bit about the infections that these types of organisms cause. Are we looking at different types of infections, more virulent infections, or are we just looking at the same type of infections like wound infections, pneumonia, different types of infections that you typically think of after operations after surgery? Are we talking about the same type of infections or new infections?

Dr. George Risi: What we’re talking about are more severe examples of the same kinds of infections. So primarily skin and soft tissue infections are what we’re seeing with these new strains of community-acquired MRSA, and these strains can cause a very simple injury to become life-threatening. People will present with enormous boils, abscesses, etc. We also see as a complication of viral infections, and especially now that we’re worried about swine flu, and before that it was bird flu, we know that one of the complications of having influenza is secondary staph infections of the lungs, and these community-acquired strains of MRSA are able to cause very severe episodes of pneumonia as well.

Dr. Sechrest: Well, being this is a discussion about orthopaedics, one of the things that orthopaedists worry about always is postoperative infections. So you come in for a relatively simple operation where the skin is incised, and you go in and you do an operation, and you close the skin. We always worry about an infection in that case anyway and it’s generally under 1%, but generally speaking you tell people, “ if you get an infection, we treat it, we may have to go back to the operating room open it up and drain it”. But in the past, we’ve always had fairly effective antibiotics that you felt relatively confident that you could clear up any sort of infection that occurred after a routine surgery. Now, you compare that with other types of more complex orthopaedic surgery where you’re leaving implants behind – metal plates, rods, artificial joints, for example, then we’ve got a whole different situation. We’re much more concerned in those cases about infection because we always felt like that if one of those things get infected, you generally have to go back in and, most of the time, remove the hardware at some point because you can’t ever be sure that you can get the infection gone unless you remove the hardware. So we’re always worried about infection in orthopaedic surgery whether we leave hardware behind or whether we don’t. What does that mean for MRSA? Or what does it mean for those two operations? Should we, as orthopaedic surgeons, be much more concerned, much more careful, should we warn our patients about this? Is there anything else that we can do?

Dr. George Risi: These are enormous topics and very, very important questions. In general, what we’ve been able to do in the past is to separate out these two different kinds of MRSA such that the hospital-acquired strains tend to not be the same as the community-acquired strains. Unfortunately there is a little bit more of an overlap now so that the traditionally community-acquired strains are becoming somewhat more endemic within hospitals. But let’s deal with the more traditional because that answers most of the issues. Most of the time community-acquired MRSA is something that is not going to be carried chronically by somebody in the nose. If someone is going in for an elective orthopaedic procedure, then it’s unlikely that they’re going to be at risk for developing this kind of a surgical site infection in the first 3 months after the surgery. So what we try and do now is identify those individuals who are chronic carriers of staphaureus of any kind – either regular staphaureus or MRSA – by sampling the nose and seeing if you’re a carrier. Because we know, when you’re talking about staph infections as complications of surgery, that most of the time that infection is going to happen as the result of your own bacteria that you are carrying and shedding being the cause of that. So if you are able to suppress the strain of staph that’s growing in your own nose for a period of time around the surgery, then the chances of developing a site infection are quite a bit lower. Now when you talk about orthopaedic surgery infections in general it’s important to break them out into the timing of when the infection happens so that if something happens in the first 12 weeks after the surgery is done, then usually that’s as the result of infection that was actually put into the site of surgery at the time of the surgical procedure, and that’s despite using antibiotics intravenously, despite cleaning the wound very thoroughly, despite all this technique, sometimes very minute amounts of organism can get into the site of the infection and because of blood clotting and scar tissue and a variety of things, those organisms are not able to be cleared out and they can cause infection. As you mentioned that happens in usually than 1% of surgical procedures in modern hospitals using good technique. When you talk however about infections that happen later on after the 3 month window then those are organisms that tend to get to that site as the result of dissemination through the bloodstream. If that happens then anything that gets into your bloodstream is possibly able to cause infection at that site and that’s much more problem if you’ve got indwelling hardware. Those complicated procedures that you mentioned where you give somebody an artificial hip, artificial knee, etc. Those large foreign bodies, which is what they are, are sites where if a bacteria gets to them there’s no blood supply going into that and so all you can do is sort of surround it but, if it gets there, then infection certainly can happen. Those are the kinds of situations where this community-acquired strain of MRSA certainly could cause orthopaedics infection as well.

Dr. Sechrest: Now you mentioned looking as to whether you’re a carrier of staphaureus or not. Are you recommending that most orthopaedic patients, who are going to have some sort of orthopaedic surgery – especially things like an artificial joint, should they be tested to see if they’re harboring staphaureus or methicillin-resistant staphaureus routinely?

Dr. George Risi: You know, I think everybody is moving in that direction. There’s very little reason not to do this. We know that there are some people who are going to be chronic carriers of staphaureus in the nose and about 20% of the general population has that as just one of the ways that they carry bacteria. About 30% of people will be transient carriers and then about 50% of people just don’t seem to be able to be colonized and don’t carry staphaureus in their nose. So identifying those people in advance, who are carriers, allows you to do additional manipulations before the surgery to try and reduce that carriage rate and to reduce the chance therefore of getting a site infection. So if you have the luxury of this being an elective procedure, patients will be brought into the doctor’s office a week or so in advance of the surgery, and get a sample taken from the nose to see if they carry staphaureus or not, and if they do carry staphaureus is it an MRSA or not. And if either staphaureus or MRSA is identified then the patient can start taking a topically applied antibacterial called Mupirocin, and that applied to the anterior nose for a few days in advance of the surgery actually will significantly reduce the chance that you are going to be a chronic carrier going into your surgery.

Dr. Sechrest: So there are some things that patients should be aware of that they can do to reduce their risk of methicillin-resistant staphaureus infection during the surgery or after surgery.

Dr. George Risi: Absolutely.

Dr. Sechrest: And surgeons, I’m assuming, should be aware of this as well.

Dr. George Risi: It’s hard to get that word out to everyone but the major surgical societies, orthopaedic surgeon society, general surgeon society, etc., are all sort of moving this same direction of identifying those people in advance and trying to do everything that they can to reduce their risk of infection. That’s not just carriage of staphaureus. It’s making sure that your blood sugar, if you’re a diabetic, is optimally managed. It’s making sure that any chronic illness is as tuned up as possible and so there’s a variety of things that can be done for any patient going into surgery to make it more likely that they’re going to have a successful outcome in terms of a variety of surgical complications that can happen to include infection.

Dr. Sechrest: So let’s move on to talk a little bit about treatment. So let’s say that I’m an orthopaedic patient and I’ve had a surgery whether or not there’s an implant involved or not, and I come down with MRSA infection. When you’re called as an infectious disease specialist, how are you going to evaluate me and what are you worried about at that point?

Dr. George Risi: Well, again, I’ll go back initially to discussing whether this is an acute surgical wound infection or delayed one, and that’s especially important when you’re talking about implanted devices. Because if one of the big things that we struggle with in orthopaedic infection is whether or not that implanted device has to be removed in order to cure the infection. We know that for chronic infections it’s very, very difficult to eliminate the infection without removing the hardware. Whereas if you have someone who has a relatively recently acquired infection that’s, sometimes the infection can be cured without that hardware. So that’s the first thing is how long ago was the surgery first of all. The next thing is that almost always some surgical procedure is required in order to help cure the infection. That usually is going to debridement or cutting away of infected tissue and whatever dead tissue the surgeon may find in order to remove anything that antibiotics is not going to be able to cure. The additional reason for going in and doing that is to get a good microbiological specimen – something you can take to the lab and culture – and determine what is the bacteria that’s causing the infection and then what are the best antibiotics to work against it. So once you’re successful in obtaining a culture and you know what the organism is, then you can choose the very best antibiotic. You know, if you have a strain of staphaureus that is sensitive to penicillin, plain old penicillin is actually still the very best drug that we could use. However, if you have an organism, an MRSA, then your options are significantly limited and you’re down to basically a handful of antibiotics that are reliably effective. Those drugs would be vancomycin, which is probably the most time-honored and the best studied of the antibiotics that we have. A couple of new ones: Linezolid, Dactomycin, and a drug called Synercid which is almost used anymore because it’s associated with a fair number of side effects especially in chronically ill people. There are a couple of oral antibiotics that we can sometimes use as well to include Trimethoprim sulfa or Bactrim, Septra, and plain old tetracycline derivatives of one kind or the other actually turn out to be very effective drugs to treat MRSA as well. So after debridement, in cutting away the dead tissue and perhaps removing hardware if we decide that it’s been infection that has been in there too long, then a prolonged course of antibiotics is necessary and we tend to follow inflammatory markers like the C-reactive protein, the sedimentation rate, the white blood cell count. And, of course, how the patient feels, how the wound looks, whether a temperature profile is, all of those things hopefully will come down in a steady fashion when they’re on the appropriate antibiotic after it’s been debrided. There’s almost no way of getting around however a very prolonged course of antibiotics for these situations. That tends to be, for adults, usually between 4 and 6 weeks of intravenous antibiotics sometimes followed by a course of oral antibiotics after that. When you’re talking about trying to salvage a joint that has prosthetic hardware in there, then there are patients who have to be on very prolonged courses of oral antibiotics and I’ve got some people for whom surgical removal was just not possible for one reason or the other. Either the patient is just too sick or it’s just too big of a procedure. It was a very, very special device that just couldn’t come out. If you took it out the patient would end up losing a limb, those kinds of situations that I think we’ve all run into over the course of time. Those situations we actually will sometimes opt for lifelong suppression and I have several people in my practice who have been on chronic suppressive antibiotics for years and years in order to keep the infection at bay, and allow them to have a functioning limb.

Dr. Sechrest: Well, and I think we all, at one point, were worried that we may start to see methicillin-resistant staph that really no antibiotics work for, and the fact that we still have some of the newer antibiotics and then some of the older antibiotics that will work even if it’s more prolonged is probably a good thing.

Dr. George Risi: Well, we’re still in that honeymoon phase where we have a few antibiotics that are relatively new. But the reason that Trimethoprim sulfa works pretty well still and the reason that tetracycline works pretty well still is that these were drugs that were not used very often in the 60s and 70s because newer drugs came out and as we’re using these drugs more and more unfortunately resistance is starting to occur with them as well. We’ve already seen strains of staphaureus that are resistant to vancomycin. We’ve already seen strains that are resistant to Dactomycin and to Linezolid. So what we really need is a commitment to new antibiotic development, number one. And number two, and I think this will happen in the next probably 5 years or so, is an effective vaccine against staphaureus that we can use to even further reduce the chances going into the surgery that you’re going to develop a staph infection. There’s active research going on in that area right now, and the results are at least promising in a preliminary fashion.

Dr. Sechrest: Well, it sounds like the other piece to this whole puzzle is prevention.

Dr. George Risi: Clearly.

Dr. Sechrest: And the whole notion of getting tested before you have surgery and watching some simple things, just trying to stop the spread of any infection, and if it happens to be a MRSA infection all the better if you can stop it.

Dr. George Risi: That’s right. That’s right. I should have mentioned earlier that if someone is identified in the hospital as being a carrier of MRSA, then we do put that patient in isolation in order to protect all the other patients in the hospital environment. That means wearing gloves, gowning, putting on masks etc., and whenever you’re interacting with that patient, to prevent you from acquiring the organism transiently and then carrying it to the next patient either on your hands or somewhere on your clothing, etc. That kind of contact isolation actually is very effective in preventing transmission within the hospital of those strains.

Dr. Sechrest: One thing I think we ought to clarify for patients because I think they’re going to want to know this and that is, you’ve mentioned that sometimes with these infections, it requires 6 weeks of IV antibiotics. In this day and age, these antibiotics are given as an outpatient. I think it’s safe to say that patients don’t have to stay in the hospital for 6 weeks just to get IV antibiotics, that this has gotten to the point where we can do this as outpatient fairly effectively.

Dr. George Risi: Yeah. That’s one of the real joys of being in practice now. You know, when I was in medical school, a very long time ago now, that was not an option. But now we have a programmable infusion pumps that you can carry around in a fanny pack. Long-term intravenous lines that can go into your arm or into the large vein below the clavicle, that will allow ready access such that people can receive very aggressive antibiotic care in the home setting, and that’s very standard now.

Dr. Sechrest: Well, I think this has been an excellent discussion about MRSA and I think it’s cleared a lot of questions that I had, as an orthopaedic surgeon, about how we should deal with this and especially some of the preventative steps that are available to try to reduce your risk of developing a MRSA infection. Is there anything in this discussion that you think that patients should know that we have not covered?

Dr. George Risi: Umm, I think the things that I think the patients should take home from this, more importantly, anything else is number one: involve their primary care physician in advance of the surgery such that whatever chronic medical conditions they may have can be tuned up to the greatest degree possible. Second thing is that, very often for elective surgery, a patient will be given a special liquid antibiotic soap to take home with them and to bathe with that the night before the surgery and sometimes the morning of the surgery as well. That will help reduce the number of organisms that are present on skin, and further reduce the chance of infection. Ask your surgeon about nasal carriage and whether they should be screened or not for nasal carriage of staphaureus and then, if they do end up being carriers then follow those instructions very, very meticulously in order to reduce the chance. Because the last thing you want to do is get an infection. We’ve been there, we can solve the problem, but it’s something that we’d rather not have to deal with anybody.

Dr. Sechrest: Well, thank you. Excellent discussion and thanks for joining us this afternoon.

Dr. George Risi: My pleasure. Thanks for having me.