Q&A: Stethoscopes Carry Loads of COVID, Other Pathogens


W. Frank Peacock, MD, FACEP, FACC, FESC: “When I intubate somebody, I need to know where the tube is, and I need to know now—like within 10 seconds. You can’t tell with anything else. Nothing is as fast as the stethoscope. I can get an X-ray, but I’ve got to wait for the X-ray while you hold your breath.”

The dirtiest instrument that a physician uses is often the not-so-trusty stethoscope. They're germ-carrying magnets that doctors take from patient to patient, leaving a trail of infection in their wake, argues W. Frank Peacock, MD, FACEP, FACC, FESC, the vice chairman of the department of emergency medicine at Baylor College of Medicine. Peacock is also the chief medical officer of a company called AseptiScope which, he claims, addresses the need to make stethoscopes less susceptible to contamination. Peacock recently sat down with Infection Control Today® to discuss just how much of a threat to infection prevention and control stethoscopes can pose, saying that the typical stethoscope hanging around a healthcare provider’s neck is a a “dirty, nasty little tool.” Peacock adds: “Stethoscopes don’t get cleaned. They rely on the user to clean them and that’s a disaster.” Only about 4% of healthcare providers clean stethoscopes according to guidelines set down by the US Centers for Disease Control and Prevention, and the CDC’s guidelines don’t go nearly far enough, saying that stethoscopes should be cleaned once a week. Peacock says that “it’s time for the CDC to update its game.” Meanwhile, this is something that the people who battle infection everyday—that is, infection preventionists—need to be aware of.

Infection Control Today®: If you can rank instruments in the hospital that are vulnerable to contamination, where would stethoscopes fall? I’m thinking just from the information that you sent to me that they’re near the top right?

W. Frank Peacock, MD, FACEP, FACC, FESC: Pretty much. We’ve done a lot of studies, and not just we, I mean, in the last decade there have been 20 of them that show the stethoscope is a dirty, nasty little tool. The reason is because we clean a lot of stuff. I mean, if I’m going to use a pair of forceps, they go to the sterile machine, you know the autoclave, and they [get taken] care of. Stethoscopes don’t get cleaned. They rely on the user to clean them and that’s a disaster. We did a study a few years ago, and just walked around to watch how many healthcare providers clean their stethoscopes after use or before use, either one, and it was astounding. And it was the same all over the United States. It’s not one dirty hospital and one clean hospital. The number was 4%. That’s how many clean their stethoscope with CDC [US Centers for Disease Control and Prevention] recommended guideline methods before touching a patient with it. And I apologize about this part of the interview because I’m going to destroy your relationship with your doctor. Because the next time a doctor comes to you with a stethoscope and holds it here, you wonder how many people has that touched today? Since the last time he cleaned it? And it’s disgusting. And when we culture these things, they are truly little vectors covered in bugs that are never washed.

ICT®: I’m sure like every medical expert, you’re keeping tabs of what’s going on with Covid-19. Has the problem with contaminated stethoscopes been taken into account by medical experts and has the alarm been sounded or no?

Peacock: So yes, there are definitely studies that show that COVID is on the stethoscope if it goes to see a COVID patient. And the problem with COVID—and everybody knows this—is that we don’t always know who's got COVID. You don't find out f[after] a few days. So, if you saw a COVID patient and then go down the hall to see another lady? What do you think the chance of that being carried? And there’s been a couple of trials that show this. That you can take a chrysanthemum— sorry, cauliflower viral DNA. It’s a funny little nonpathogenic virus and you can put it on a patient. And then the doctor goes and listens to the patient and then they go and culture the next patient down the hall and they got it. How did they get it? The stethoscope carried it to them and rubbed it on them. And you can take the stethoscope and you can put it on an agar plate after seeing a MRSA [methicillin-resistant Staphylococcus aureus] patient and

W. Frank Peacock, MD, FACEP, FACC, FESC

there’ll be MRSA that grows out on that. So, it’s really quite clear that the stethoscope is able to carry bugs. It is able to be a vector. You know we’ve been washing hands. Ignaz Semmelweis was the first guy who said you should wash your hands 150 years ago. We’ve been supposed to wash our hands for 150 years now. And when he came out, everybody resisted. “Oh no, that doesn’t cause any problems.” And all these women were dying in labor and delivery because the doctors weren’t washing their hands. And so now it’s just part of the vernacular—we always have to wash our hands. What’s really wild is the same bugs that grow in your hands are the ones on your stethoscope. We consider the stethoscope your third hand because of the identical bugs. So, if I have to wash my hands between every patient, why would I rub a stethoscope across the same patient that I didn’t bother washing? We know nobody washes it because it is a total pain to wash your stethoscope. To do it right, you are supposed to take an alcohol swab and rub it for a minute. And even when you do that, 20% to 30% of the stethoscope will still be dirty. But it does kill a few bugs to rub your stethoscope so you wash your stethoscope between patients. I work in the ER. On a busy shift, I’ll see 50 patients. If I take a minute for every before and after every patient to wash my stethoscope—that’s almost two hours a day I have to be washing my stethoscope. Guess what’s going to happen? I'm not going to be washing my stethoscope. This is just our reality. We have gloves. We have barriers for our faces and hats and gowns and shoes. But our stethoscope sticks out there like a dirty little thing. It’s just unbelievable that this has escaped any kind of an address by the medical community. And when you tell people, they go “no this doesn't cause it.” It absolutely does. There’s a case report already out there on a cardiology fellow getting COVID after she intubated somebody and had to pull out her stethoscope to listen to where the tube was and then put it back in and she got COVID from that.

ICT®: It’s interesting that you mentioned washing your hands and how it should be natural that healthcare providers wash their hands. But as you know, better than I do, hand hygiene compliance has never been as good as it should be among healthcare workers, perhaps for the same reasons that you mentioned why people don’t seem to bother trying to clean their stethoscopes as much as they should.

Peacock: I would rank hygiene in a different category. There’s the disease I give you and the disease I get. It’s always more effective to think that you’re protecting yourself. Because you know, it’s busy, I’m not really sick, I can see this next patient. But if you think I’m gonna get sick and die from this? If you remember the HIV years, and in the old days, we got blood on us all the time, and when HIV comes out and all sudden everybody realizes that getting blood on you can kill you. Nobody gets blood on them anymore. Well, it’s the same way with these bugs. And when COVID comes out, everybody realizes “I’m going to get COVID and die.” Now everyone’s trying to stay clean. So, we wear gloves. I don’t see patients without gloves on anymore. I used to, but I don’t anymore, because I don’t want to get COVID. The stethoscope has a glove and that’s the whole point of this is that now we can protect our stethoscopes. You know this disposable stethoscope stuff is just baloney. If you think of the stethoscope as a tool, and this is a study we just got published, and we looked at 800 encounters, and if you use a disposable stethoscope, the probability of making a wrong diagnosis was 10.9%. If you use the quality stethoscope with a barrier on it, the diagnostic error rate was zero. So, there is no harm to the stethoscope by putting a barrier on it, it just keeps you from infecting your patient with whatever was on your hands and now on your stethoscope. So, it is an ability to provide safety for you. But it is also for the patient. But it’s also for you because now I don’t have to use a disposable stethoscope. Think what’s on that disposable stethoscope. It’s all the crap that everybody who ever touched it and put on it. You know, in the HIV years, it’s when you have sex, somebody who’s unprotected. It’s like having sex with all the people they had sex with. When you use a disposable stethoscope with somebody who’s not protected, it’s like I touched everything they ever touched. I don’t want to have that on me. So, this is a protection for the patient. And it’s protection for the doctor. And that’s the key. The whole trick is how do you protect them? You wash your hands, then you pick up your stethoscope and put a barrier on it. Well, that doesn’t make sense. Because now the stethoscope, which was dirty and now is in my hands, it’s like I didn’t wash them. Or I can wash the stethoscope and then try to put the barrier on it with my hands and I just infected it. So, the whole trick [with the barrier] is it’s touch-free. You don't have to touch anything. You go in there, you wash your hands, you listen to the patient, you put the barrier on it without touching it, you listen to the patient, you throw it off and you leave the room. So, everybody is protected. That’s what we’re trying to get here. Instead of, you know, rubbing dirty things on people and carrying them myself, you know the scope goes around your neck. That’s pretty gross. I mean, think about that. And the important piece here is the things that are dirty are the fingertips and the palm. Back of your hand is not so dirty. The important stuff on the stethoscope is the diaphragm is nasty. The tube doesn’t have much on it. And if you look at pure counts of bugs, it’s the fingertips and the diaphragm is where the money lies.

ICT®: The CDC just came out with a something called Project Firstline. It’s an $800 million program aimed to educate healthcare workers about infection prevention. As it sprang from everything we’ve experienced with COVID-19. Is the CDC aware of what’s going on with stethoscopes? I mean, you just mentioned earlier they’ve measured that only less than 4% of stethoscopes are cleaned properly after use. So, the CDC, I have to assume, is aware. Do they see it as the kind of problem that you seem to think it is?

Peacock: It’s really easy to dig on the CDC. And I’m going to try to be fair about this. The guidelines came out in 2008. They have been updated, and what they say is that the stethoscope might be a vector, but it should be cleaned once a week. They write that you should wash your hands between every patient and then not clean your stethoscope except once a week and that’s sort of insane. It doesn’t pass the sniff test at all. So, because if your hands are dirty, and your stethoscope is dirty, and they can cause diseases and transmit vectors, be a vector for transmission of disease, why would you think that it’s OK to wait a week? And so, I actually think it’s time for the CDC to update its game. If you read the guidelines, they say we think it might happen. I’m trying to be fair to CDC and this data only recently came out that it’s been proven that the stethoscope can transfer bugs around. Bugs that are very nasty like MRSA and C. diff, anything you want to have moved down the hall. COVID from patient to patient. The stethoscope can be the vector. So, once a week is just not acceptable, we need to move on from that.

ICT®: A lot of medical devices are kind of transitioning to being disposable. I’m thinking particularly about duodenoscopes. They came out recently with disposable duodenoscope, or at least duodenoscopes with parts that are disposal. But you’re saying that disposable stethoscopes are flawed because they don’t quite catch what a normal stethoscope catches, right?

Peacock: Sure. So, the things that you’re talking about making disposable are those things that are very difficult to make safe. The duodenoscope: It’s a real problem to sterilize that. Once it’s gone down into somebody with HIV, I’m not really excited about having it go down in me. So that’s why you make it disposable. The thing is, it’s really easy to sterilize a stethoscope. You just put a barrier on and it’s done. We’ve done that study. We took blood that was infected, pus, stool, urine that was infected and sputum and smeared it on a group of stethoscopes. And then we set them there and we cultured them at an hour, 3 hours, and 6 hours, 24 hours. Those that were just cultured, were covered in bugs, as you'd expect: MRSA, C. Diff. The ones that had the barrier were sterile. We can make a stethoscope sterile for pennies, or you can use a disposable stethoscope which would get me infected, is a toy, it’s a piece of garbage, it doesn't work very well, for like three bucks. It’s like this is a no-brainer. So, I can make the stethoscope safe. Duodenoscope? Not so sure, so make it disposable. But the stethoscope—and I have a good quality one, I have a Littmann 3200—it’s a great stethoscope. It records. It’s wonderful. If I don’t clean it, it’s nasty. I can make it safe for a few cents with a touch-free barrier.

ICT®: Do you have a stethoscope with you? Give me an idea of how this barrier would work if you can.

Peacock: OK. So, here’s the Littmann 3200. It’s my stethoscope. Records. Really nice little machine. And I can go rub it on a dirty patient. And then I go down the hall to the next dirty patient and rub it again and I put it on my neck, and so I spread the disease around from patient to patient, or I can go over to my machine—takes one second—and I put that on it and we’re done.

ICT®: So that’s the cover on the stethoscope? And you remove that cover for each patient and put it back on for each patient?

Peacock: No, no, you walk into the machine and the machine sticks it on there and you’re done. And then you go see the patient and when you’re done. You remove that and throw it away. When I need another one, I go to the machine. There it is and then I go see that patient. So, you can see why this is cheap. It’s a piece of plastic. The key is that it’s touch-free. I don’t have to handle it and put it on because then my finger just touched it now. It’s dirty. So, the idea is my stethoscope hangs on my neck like it always does. I go see my patient; I wash my hands. I see Mr. Jones, I do everything. And I go listen to your chest. Can you sit up? I listen to his chest with the stethoscope cover on and we’re good. And then I walk out of the room. This goes in the garbage with my gloves. So, this comes off, gloves go off and off to seethe next patient. I wash my hands. Put on my gloves. Listen to Mr. Jones. Time to listen to him. Here we go put on my sticker. I’m good.

ICT®: That’s interesting. Why hasn't the healthcare system recognized this problem? It seems a little obvious. If they have recognized this problem before, it seems as if they have just thrown up their hands and said, “Well, it’s one of like a million problems we have to face. Michael Millison, who’s an internationally known healthcare expert, has taken the healthcare system and the CDC to task because he argues that they haven’t taken infection prevention seriously enough. Is this possibly a result of that unserious attitude toward infection prevention?

Peacock: Well, so I think somebody had to make a dispenser. There have been stickers out there and, you know, they look like caps and hats that you put on your stethoscope. But the problem is you’re doing it with your hands and it’s still dirty but it’s a different kind of dirty. But it’s just dirty like it was before. So that the trick was it had to be a touch-free system. It’s estimated that a couple hundred people die every day of healthcare acquired infections. C. diff is particularly difficult. You can go wash your hands your stethoscope all afternoon, but that doesn’t kill the spores. So, the barrier has to be the piece that moves forward. The idea that you should just wash your stethoscope more isn’t going to solve the problem because you can’t kill C. diff. Get some alcohol and rub it on their but it will not kill the spores. And you’ll spread those to the next patient. We did that trial too, and it’s going to be published in the next couple of weeks. It’s already been accepted. Where we put C. diff on a stethoscope, put some barriers on, didn’t put some barriers on the control group. And we checked in 24 hours. The barrier stethoscopes remain sterile, the un-barriered stethoscopes covered in C. diff.So it’s a different strategy than we’ve done historically. The idea is before we just wash our way out of it, that doesn’t work. First off, doctors don’t wash it, and not just doctors, nurses—nobody washes their stethoscope. And even when they do, it’s still hard to clean it. It’s just a difficult thing. And a barrier is a one second. Nothing. Boom and done.

ICT®: My readership comprises, as you know, infection preventionists and many of them have a nursing background, and they in general don’t carry a stethoscope. I assume they should welcome this. Because they are always on the lookout for contamination and ways to prevent infection and control infection. This is probably an aid to their jobs?

Peacock: Yes. For those people that use stethoscopes. And it’s not everybody, I understand that. But for those people who do, this allows you to have a quality tool, as opposed to a toy. You know, I have a two year old who has a disposable stethoscope. And that’s about where it should end. You know, it’s just if you have a good quality stethoscope, I mean, that is the way to do it. And they’re things that people say, “Well, I don’t need a stethoscope for everything.” No, you don’t. I don’t use a stethoscope for a broken leg. But if I have an asthmatic or somebody with emphysema or COPD exacerbation, I really have to have a stethoscope because I can’t tell. Ultrasound doesn’t change that. When I intubate somebody, I need to know where the tube is and I need to know now—like within 10 seconds. You can’t tell with anything else. Nothing is as fast as the stethoscope. I can get an X-ray, but I’ve got to wait for the X-ray while you hold your breath. So, it’s really an advantage to have a quality tool that’s safe.

ICT®: Intubation is a very common thing with COVID-19 unfortunately.

Peacock: Yes, as rough as it is.

This interview has been edited for clarity and length.

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