Podcast: Emerging multidrug-resistant bacteria
Transcript
Emily Hughes: Welcome back listeners to another CMAJ podcast. I'm Emily Hughes, third year medical student at the University of Toronto and medical intern for CMAJ. Today we are discussing emerging multidrug-resistant bacteria. An important topic, new strains of multidrug-resistant micro organisms are constantly emerging, but it's challenging for physicians to keep informed of the various new strains. I'm speaking with Dr. Jennie Johnstone, infection prevention and control physician-scientist at Public Health Ontario and infectious disease specialist for St. Joseph’s Health Centre in Toronto. Dr. Johnstone co-authored a CMAJ practice article titled "Five things to know about...Emerging multidrug-resistant bacteria." in which she describes a strain of gram-negative bacteria that is resistant to multiple antibiotics. Dr. Johnstone is joining me from Toronto. Hello, Dr. Johnstone, welcome to the show.
Jennie Johnstone: Thank you for having me.
Emily Hughes: We're glad to have you here. So let's dive right into the questions. There's one particular multidrug-resistant bacteria that you want to draw attention to today. What is it?
Jennie Johnstone: Yes, so I wanted to talk about CPE, which is called a Carbapenemase-producing Enterobacteriaceae, which I realized is a mouthful. But essentially the CPE or just your regular gram-negative bacteria, like E. coli or Klebsiella or Enterobacter that you encounter on a day to day basis. But these specific Gram-negative bacteria have acquired a resistance mechanism to carbapenems. Carbapenems, as you may know, include antibiotics like meropenem, ertapenem, imipenem. And these are very, very broad spectrum antibiotics that we use, typically only in the very sick population, or in patients with very resistant bacteria. And so if these bacteria are resistant to the carbapenems, it leaves us with very few if any options for treatment.
Emily Hughes: Absolutely something important for physicians to be informed about. How common is CPE? Is the incidence increasing?
Jennie Johnstone: Well, fortunately, CPE is still relatively rare in Canada. But I think what we're concerned about is the trajectory. So CPE was really only identified in Canada in 2008. And in 2008, we only had about five cases identified. But now in 2016. Last year, we identified 779 cases. And if you look at the curve, it's exponentially increasing. Certainly that's our experience here in Ontario as well. We had the first case identified in 2008. And then last year, we had over 250 cases identified.
Emily Hughes: A very timely topic to be discussing today. How is CPE acquired? Who is at risk?
Jennie Johnstone: In Canada, CPE is essentially an organism that you would acquire in hospitals. And so essentially, it's spread like most nosocomial pathogens. You can acquire from the contaminated hands of health care workers, or for contaminated shared patient equipment. There's some well documented outbreaks associated with a specific type of endoscope called the duodenoscope. And this has been a way that CPE has been transmitted down in the United States. And in Europe, for example.
Emily Hughes: Are there any populations of patients who are at risk for CPE more than others?
Jennie Johnstone: That's a great question. And there's a lot we don't know about CPE because this is an emerging pathogen. So in terms of acquiring CPE, I should mention that many patients are just colonized with CPE, meaning they're completely asymptomatic. They just have these E. coli and Klebsiella and Enterobacter that are resistant, residing in their GI tract and not doing anything, and it doesn't seem, it doesn't seem like anybody is at particular risk of colonization. However, it seems that patients who are very sick are the ones who go on to develop infection.
Emily Hughes: I actually want to talk a little bit about how CPE is identified and the symptoms associated with it. So you mentioned that it can be asymptomatic. Are there any symptoms of infections?
Jennie Johnstone: Well, the CPE are your typical E. coli or Klebsiella or Enterobacter, and so they will present as an infection just like a regular E. coli infection. So this might be a urinary tract infection due to E. coli, or it could be a pneumonia. If the patients are critically unwell in the hospital and have a ventilator-associated pneumonia or health care associated pneumonia. It also could be sepsis, so having this resistant E. coli or Klebsiella or Enterobacter in their bloodstream. It could be a surgical site infection. Its just your regular presentation of these organisms. However, they just happen to be very resistant.
Emily Hughes: And are there any treatment options for CPE?
Jennie Johnstone: Well, it's variable. Its essentially as mentioned, they are resistant to the carbapenems, as well as any of the penicillin or cephalosporins. And some are susceptible to more toxic agents like gentamicin or amikacin. But some are also resistant to that. Some are susceptible to colistin. But there's an another emerging resistant mechanism that is making these organisms resistant to colistin. And there have been reports of some CPE that have no susceptibility to any antibiotic.
Emily Hughes: In patients who are colonized with CPE, but are asymptomatic should they receive treatment?
Jennie Johnstone: So at this point in time, we there is no recommendation to treat patients who are colonized. If patients who are colonized, meaning the organisms just residing in their guts, and their patients are completely asymptomatic, if they're in hospital, we do recommend that they are in a single room and are on contact precautions or in isolation. However, first of all, we really don't have any antibiotics to treat it. And second of all, there's no evidence that that would be useful.
Emily Hughes: What are some of the best ways for the public and also for physicians to prevent the spread of CPE and other drug-resistant bacteria?
Jennie Johnstone: I think that's a great question, because I think everybody wants to know what they can do to help. In terms of at the individual level, so at the physician level, I think it's really important to do the simple things very well like making sure you wash your hands between patients, and making sure you clean shared patient equipment, even your stethoscope in between patients, so you're not spreading it around. It's also important as we learn more about antimicrobial stewardship. So that's making sure that you're using the right drug for the right duration, at the right dose for only as long as you need it. And considering whether or not you even need antibiotics at all. Because we know the more antibiotics you use, the more antimicrobial pressure exists. And that leads to antimicrobial resistance. In terms of on a broader scale, this has been identified as a global priority both by the WHO as well and the UN. And certainly the Canadian government has identified antimicrobial resistance as a big problem. And I think we really need a coordinated response. And that's focusing on your One Health. So making sure that we limit the number of antibiotics used in our animal supply. And as well, making sure again, we limit the number of antibiotics used at the level of patients, making sure we perform good infection control within hospitals so that we aren't spreading these organisms. And finally, I think there has to be a focused effort on medications and developing new antibiotics in order to combat these, these organisms. It CPE has been identified as the number one priority in terms of development of new drugs by the WHO, and I think this is critical.
Emily Hughes: Absolutely. Beyond CPE, are there other multidrug-resistant bacteria that physicians should also be aware of?
Jennie Johnstone: Well, there are a number of antibiotic-resistant organisms and I think we're only going to hear about more moving forward. I think many of us know about MRSA and VRE, which is your resistant Staph aureus and resistant Enterococcus, as these have been around for a while. I think the number of expanse of gram-negatives that are becoming more resistant is growing. So we're hearing about CPE. I mentioned that there is now this new colistin-resistance that is popping up in gram-negatives. And this is due to a resistance mechanism called MCR-1 that we're only just starting to learn about. Pseudomonas is known to be resistant and is increasingly becoming resistant. Just in the news over the last few weeks, we've heard about completely resistant gonorrhea. And just yesterday, Public Health Agency of Canada publicized resistant Candida, which is a type of yeast that can be resistant to almost all the antifungals that we have. So yes, I think as we move forward in time, there's going to be a growing number of antibiotic-resistant organisms. And I think what I think about my infectious disease practice in 10 years time, the drugs we use and the way we treat infections is going to be very different than it is today.
Emily Hughes: What efforts are undertaken with regards to surveillance for CPE?
Jennie Johnstone: So surveillance for CPE is different according to province. There are a couple of provinces that have made CPE a reportable disease, including Alberta and British Columbia and this may make it easier for hospitals to have more information about who is coming to their hospital and who may be colonized to CPE. And it may help prevention efforts. In Ontario, we have a voluntary CPE reporting structure whereby any CPE that's sent to our provincial lab, we then go back to the hospitals and ask them to complete a questionnaire. And we do generate a quarterly newsletter that updates the status of CPE. Again, it is voluntary, but we do have close to 100% response rates, which is fantastic. However, it would be more helpful to have patient-level information. Right now we are able to present these data in aggregate form which helps identify the changing landscape of CPE within within Ontario. However, this isn't used as a communication strategy to hospitals, and certainly hospitals don't know if somebody's known to be CPE in another hospital, for example. And it would be great if we could have some mechanism to increase our communication between hospitals so that we don't have unintended spread. If if a patient is already known to be CPE positive in a different hospital.
Emily Hughes: Absolutely. I'm wondering now, you know, I think this ties in nicely with my next question, what should physicians do if they suspect a CPE outbreak in their hospital?
Jennie Johnstone: It's really important. CPE again, is still relatively rare. And so if you see a patient who has CPE say it pops up in just a regular microbiology specimen, so a urine or a sputum and you weren't, you didn't know that patient had CPE, it's really important to first make sure there's been no spread to other patients. And as well to try and figure out what the source of the outbreak could be. I would recommend getting somebody who is experienced in CPE to help advise on what the next steps are. Certainly, it's essential to make sure that there's excellent adherence to hand hygiene and cleaning up shared patient equipment. I can tell you anecdotally there has been some experience finding that outbreaks are due to sink drains and shower drains and we're realizing more and more that the patient sink and patient showers could be a potential reservoir leading to outbreaks in hospitals. It certainly keeps me up at night, thinking about this organism and and what what it could do if we are if we're not careful.
Emily Hughes: Thank you so much for speaking with us today, Dr. Johnstone.
Jennie Johnstone: Thank you for having me.
Emily Hughes: I've been speaking with Dr. Jennie Johnstone, an infection prevention and control physician-scientist at Public Health Ontario and infectious disease specialist for St. Joseph’s Health Centre in Toronto. She co-authored a CMAJ practice article titled "Five things to know about...Emerging multidrug-resistant bacteria." The key points from this article were covered in this episode. To read the article she co-authored, visit cmaj.ca. If you've been listening to our CMAJ podcasts, let us know how we're doing. Please leave us a rating on iTunes or give us your feedback on Soundcloud or any of our social media channels.