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Clostridioides difficile testing: Finding the Sweet Spot · The SHEA Podcast

• 0:08
  SPEAKER_01: Welcome to the Diagnostic Stewardship Podcast brought to you by the Society for Healthcare Epidemiology of America, Shay, promoting the prevention of healthcare associated infections and antibiotic resistance and seeking to advance the field of healthcare epidemiology and antibiotic stewardship.
• 0:25
  SPEAKER_01: Shay is excited to launch the first episode of this podcast, sturdyoides difficile testing, finding the sweet spot.
• 0:32
  SPEAKER_01: Underdiagnosis of the C.
• 0:34
  SPEAKER_01: diffacil infection leads to worse patient outcomes and increased transmission.
• 0:38
  SPEAKER_01: However, with sensitive nucleic acid amplification tests, overdiagnosis of C.
• 0:42
  SPEAKER_01: diff has become more common.
• 0:44
  SPEAKER_01: Specifically, overdiagnosis of asymptomatic C.
• 0:47
  SPEAKER_01: diff colonization could lead to increased costs, overreporting of hospital-acquired infection rates, and further disruption of patients' microbiomes if treated.
• 0:56
  SPEAKER_01: This podcast will focus on finding the sweet spot for C.
• 0:59
  SPEAKER_01: diffaceted testing with a focus on diagnostic stewardship.
• 1:04
  SPEAKER_01: I'd like to welcome today our two panelists, Dr.
• 1:06
  SPEAKER_01: Michael Calderwood, an associate professor of medicine at the Geisel School of Medicine at Dartmouth, and the Regional Hospital Epidemiologist and Medical Co-Director of the Collaborative Healthcare Associated Infection Prevention Team at Dartmouth Hitchcock Medical Center in New Hampshire, and Dr.
• 1:23
  SPEAKER_01: Curtis Donski, a professor of medicine at Case Western Reserve University, and the hospital epidemiologist at the Cleveland VA Medical Center.
• 1:32
  SPEAKER_01: My name is Whitney Buckle, and I will serve as your moderator.
• 1:35
  SPEAKER_01: I would like to get started with our first question to frame our discussion today.
• 1:39
  SPEAKER_01: Can you share some patient examples of underdiagnosis and over-diagnosis of Cetus and how testing algorithms may impact this diagnosis?
• 1:47
  SPEAKER_00: Sure.
• 1:47
  SPEAKER_00: So underdiagnosis of chlostrium difficile was a significant concern 10 to 15 years ago when most facilities used insensitive enzyme immunoassays for toxin as a standalone test.
• 2:00
  SPEAKER_00: There are many reports in the literature from that time of patients with fulminant C disinfection leading to cholectomy or death where the diagnosis was missed because they had prior negative toxin tests by enzyme immunoassay.
• 2:14
  SPEAKER_00: And the poor sensitivity test also contributed to over treatment because clinicians often, you know, treated patients with a suspected C disinfection empirically despite negative test results.
• 2:26
  SPEAKER_00: So there was a clear need for more sensitive tests, and that contributed to the development of PCR and other nucleic acid amplification tests that are very sensitive for detection of toxin genes.
• 2:38
  SPEAKER_00: And a positive test indicates the presence of a toxin-producing strain of C defacyl, but not necessarily a free toxin.
• 2:46
  SPEAKER_00: So the good news is that underdiagnosis, uh, which formerly was a major issue, has really not been an important issue since the switch to PCR.
• 2:56
  SPEAKER_00: The major issue now is a potential for over-diagnosis.
• 2:59
  SPEAKER_00: I'll let Michael give some examples of that.
• 3:02
  SPEAKER_02: Sure.
• 3:02
  SPEAKER_02: And thank you very much.
• 3:04
  SPEAKER_02: So I agree.
• 3:05
  SPEAKER_02: I think that's a wonderful historical perspective.
• 3:08
  SPEAKER_02: And as we have moved to the more sensitive PCR assay, we need to be aware that what we are detecting is the presence of DNA or the potential to form toxin.
• 3:22
  SPEAKER_02: But if we look at the population of patients entering into the hospital, so at the time of hospital admission, it is estimated that around 10% are going to be asymptomatically colonized with C.
• 3:36
  SPEAKER_02: difficile.
• 3:38
  SPEAKER_02: And so these are patients who you will find are carrying a strain of C.
• 3:42
  SPEAKER_02: diffacyl with the potential to form toxin.
• 3:46
  SPEAKER_02: But all you know from the PCR assay is that the DNA is present, but if they are PCR positive and toxin negative and don't have a clinical syndrome consistent with active disease, the question is what is the significance of that?
• 4:01
  SPEAKER_02: And I think we'll get more at that today.
• 4:04
  SPEAKER_02: So a lot of us have been kind of thinking about well, if we were to broadly apply the PCR, what are we going to detect?
• 4:13
  SPEAKER_02: And so this idea of overdiagnosis, you know, a few examples.
• 4:17
  SPEAKER_02: It's not uncommon that someone will have a single voluminous bowel movement, and uh someone will say, well, it smells like C diff.
• 4:27
  SPEAKER_02: And a C.
• 4:28
  SPEAKER_02: diff test is ordered, and then it may take you know another 24 or 48 hours for another stool to occur, and that eventually gets sent because the order is sitting there waiting, and they don't truly have diarrhea.
• 4:42
  SPEAKER_02: Or they have diarrhea for another reason, they're on laxatives, and that's the reason for their diarrhea.
• 4:48
  SPEAKER_02: Or we've even had people that have been prepped for colonoscopy, and this has been well reported at multiple sites and studies, where we've given them the diarrhea and then we send a test, and what is the significance of that?
• 5:01
  SPEAKER_02: And so when people have looked at this, you know, at a conservative estimate, it's thought that about a third of patients tested for CDIF don't have uh clinically significant diarrhea.
• 5:11
  SPEAKER_02: People that have looked at what they're publicly reporting, you know, it's around 15%, at least in one study, that were thought to have been tested uh inappropriately.
• 5:21
  SPEAKER_02: And so we really want to be thinking about the impact of this testing and the impact of the overdiagnosis.
• 5:29
  SPEAKER_01: So it sounds like a lot of the concerns are around asymptomatic colonization, which really wasn't around 10, 15 years ago and has been an advent of these very sensitive tests.
• 5:41
  SPEAKER_01: What do you feel are the clinical and epidemiological impacts of asymptomatic C diff colonization?
• 5:49
  SPEAKER_00: Yeah, so the major concerns are related to the potential for transmission by asymptomatic carriers.
• 5:56
  SPEAKER_00: Although, you know, individual asymptomatic carriers present a lower risk for transmission than patients who have an active C diff infection, carriers in general tend to outnumber patients with CDI and they're not in isolation.
• 6:10
  SPEAKER_00: There is some convincing evidence from uh whole genome sequencing studies that carriers can contribute to transmission, again, not to the same degree as as CDI cases, but uh still a substantial uh proportion.
• 6:24
  SPEAKER_00: This is really an important issue because our most basic uh infection control measures do not address asymptomatic carriers.
• 6:31
  SPEAKER_00: Uh alcohol hand sanitizer and a lot of the disinfectants that we use uh do not kill spores.
• 6:37
  SPEAKER_00: Uh and there's a lot of uh debate about whether we should be doing things like screening and isolating carriers, but uh I think most of us do not feel that that's really a very feasible option.
• 6:49
  SPEAKER_00: There are some relatively straightforward uh measures that might be helpful.
• 6:53
  SPEAKER_00: Uh so for example, in our facility we use a sporocytable disinfectant for all post-discharge cleaning because we find that spores are often present in non-CDI rooms, and we encourage patients uh to do hand hygiene with uh soap and water.
• 7:07
  SPEAKER_00: And then again, the other major issue, as Michael alluded to very nicely, is that you know, patients uh who are asymptomatic carriers who receive a laxative can have some loose stools and be diagnosed with CDI without truly having disease.
• 7:22
  SPEAKER_02: I'll weigh in on that.
• 7:23
  SPEAKER_02: And actually, I I'm glad you brought up the point around um kind of universal use of asporoidal either for uh daily cleaning or for terminal room clean.
• 7:33
  SPEAKER_02: And that's something that I think is uh important and we ought to kind of learn more about because I agree with you that there is a number for papers and uh evidence to suggest that a lot of the transmission in the hospital is not from the patients we know about, but potentially from those that are colonized that we don't know about, and trying to ameliorate that risk is important.
• 7:55
  SPEAKER_02: And so I agree that you know there is some transmission risk from those patients who are asymptomatically colonized.
• 8:01
  SPEAKER_02: This has been looked at and um you know, as mentioned, it's not as high.
• 8:06
  SPEAKER_02: So, what are the actual numbers?
• 8:08
  SPEAKER_02: If you look at skin or environmental contamination, you know, it's only about one out of five asymptomatically colonized patients with C.
• 8:16
  SPEAKER_02: diff where you can actually document C diff spores on their skin or in their surrounding environment.
• 8:23
  SPEAKER_02: In addition, the actual bacterial load in the stool of these patients is much lower.
• 8:28
  SPEAKER_02: It is present, but it's much lower than in patients with uh active disease.
• 8:33
  SPEAKER_02: And so the transmission risk, as was said, is lower.
• 8:37
  SPEAKER_02: You know, I think thinking about does someone have diarrhea, that's going to increase their risk for transmission.
• 8:44
  SPEAKER_02: And so if you get to a syndromic-based precautions, I think everyone with diarrhea, particularly if they're being worked up for an infectious etiology, uh, needs to be on precautions where you're doing that evaluation.
• 8:58
  SPEAKER_02: I think one thing we do need to focus on, however, are the potential harms.
• 9:02
  SPEAKER_02: And so as we are identifying more people with uh asymptomatic colonization, you know, some are now going and putting them on precautions.
• 9:12
  SPEAKER_02: And so it now is putting them in a private room where you'd require gown and gloves to go into the room, and there are some benefits from the transmission side, but there are also a number of unintended consequences.
• 9:24
  SPEAKER_02: We know that patients on precautions tend to be seen less during the day by both the physician and nursing staff.
• 9:31
  SPEAKER_02: There's worse visibility and monitoring, and so there are some adverse impacts in terms of falls.
• 9:36
  SPEAKER_02: They have some delays in testing and procedures because uh they can't be taken to certain areas of the hospital without preparation.
• 9:43
  SPEAKER_02: And there's psychological stress.
• 9:45
  SPEAKER_02: Patients on precautions will tell you they are less satisfied, more anxious, more depressed.
• 9:52
  SPEAKER_02: And then when we kind of think about uh the other impacts, you know, a lot of what has to be done to mitigate the risk is making sure that we are adequately cleaning the rooms.
• 10:03
  SPEAKER_02: And as we increase the number of rooms that we are cleaning to the level that we would for C to Facil, it's increasing the workload on our environmental services staff, which are always understaffed, but trying to think about how to best use that resource is something that we are straining.
• 10:24
  SPEAKER_02: And then the last one is I do worry in terms of treatment of these patients who are asymptomatically colonized because it does increase the risk for these patients in the future if they're treated for their asymptomatic colonization, that in the future they'd be at a higher risk both for prolonged colonization and at risk for development of clinical disease due to disruption of the gut microbiome.
• 10:48
  SPEAKER_01: Thank you so much, Michael and Curtis.
• 10:50
  SPEAKER_01: I think that you have both brought up great points that relate to room cleaning, contact precautions, impact on the microbiome.
• 10:58
  SPEAKER_01: I know from my discussions with colleagues across the country, many infection control and prevention programs, as well as antibiotic stewardship, are starting to talk about pursuing diagnostic stewardship related to C.
• 11:08
  SPEAKER_01: difficile.
• 11:09
  SPEAKER_01: How do you think that we can use diagnostic stewardship as a tool to impact some of these concerns that you have?
• 11:18
  SPEAKER_02: So, this idea of diagnostic stewardship is really uh starting a conversation and helping frontline staff to think about the indications for testing.
• 11:31
  SPEAKER_02: And so, ways that you can do this are uh both kind of educating on what is needed for a clinical diagnosis of C to Facile.
• 11:42
  SPEAKER_02: And so typically we require kind of three or more unformed stools in a 24-hour period in a patient who is not currently on laxatives and has some other clinical symptoms, um, whether that be abdominal pain or fever or leukocytosis, and they're kind of a list of things one could go go down.
• 12:02
  SPEAKER_02: And so hospitals have begun uh at least to alert providers when they're putting in an order for C.
• 12:09
  SPEAKER_02: diffacil of these criteria and really making people think about whether those are present.
• 12:16
  SPEAKER_02: Some hospitals also are looking at uh the ability to screen the electronic health record uh for nursing documentation of the number of stools or the consistency of stools.
• 12:28
  SPEAKER_02: That's obviously dependent on the uh accuracy and the completeness of your electronic health record, and so there are some limitations that are there.
• 12:38
  SPEAKER_02: Hospitals that have kind of implemented these strategies have seen a reduction in their numbers of uh hospital onset cases of C.
• 12:49
  SPEAKER_02: diffacil.
• 12:50
  SPEAKER_02: And there's been this question: well, how much of this is because you are looking the other way and you are not identifying patients who ought to be treated.
• 13:01
  SPEAKER_02: And so it's important to note that uh hospitals that have done this have actually seen no increase in mortality, length of stay, ICU stay, or toxic megacolon or the need for colectomy, kind of the metrics one might look at to say that we are causing unintended harm.
• 13:18
  SPEAKER_02: In addition to that, there have been improvements in terms of patient satisfaction, the ability to get out of the room to work with folks like physical therapy to shorten uh hospital length of stay.
• 13:30
  SPEAKER_02: So those are kind of the benefits as well.
• 13:32
  SPEAKER_02: We can talk a little bit more as we go on about how do you implement this.
• 13:36
  SPEAKER_02: I think that there are some things to be aware of, but why don't I stop for a moment and uh hear the other side?
• 13:43
  SPEAKER_00: Sure.
• 13:43
  SPEAKER_00: So I agree with Michael that there are some real positives uh for CDF diagnostic stewardship.
• 13:50
  SPEAKER_00: It is important, however, for facilities that are implementing CDF test stewardship to be aware of three potential negative impacts.
• 13:59
  SPEAKER_00: The first of these, although there have not been reports of adverse outcomes thus far in the literature, there is really the potential for patient harm if cases are missed or if there are delays in making the diagnosis of CDI.
• 14:14
  SPEAKER_00: Reflexively canceling C diff orders for patients on who are receiving laxatives is a potential issue because many of these patients have also received antibiotics that put them at risk for CDI.
• 14:24
  SPEAKER_00: And clinical evaluation really is needed to determine if a C diff test is indicated.
• 14:29
  SPEAKER_00: And there really is a danger that cases could be missed if there's too much emphasis on minimizing testing.
• 14:36
  SPEAKER_00: And again, that is particularly true if determinations are made based on chart review, which is notoriously inaccurate for diarrhea symptoms.
• 14:44
  SPEAKER_00: So I think programs need to be aware of the potential for those adverse effects.
• 14:50
  SPEAKER_00: The second potential uh negative impact of diagnostic stewardship interventions could be a contribution to the spread of C diff.
• 14:58
  SPEAKER_00: You know, more liberal testing approaches, for example, uh the use of algorithm-based testing with less restrictions on testing, will detect asymptomatic carriers or patients with mild CDI who can be put on contact precautions to reduce the risk for transmission.
• 15:14
  SPEAKER_00: And then, you know, the final potential negative impact is related to the fact that many reported stewardship interventions have focused only on tests ordered on or after day four of admission when a positive test would be deemed a healthcare associated case.
• 15:30
  SPEAKER_00: And this is a potential credibility issue for your program because it suggests that the goal is not really to improve patient care but to reduce uh healthcare associated infection rates.
• 15:42
  SPEAKER_00: So if it's a bad idea to do inappropriate testing on day four, uh it should also be a bad idea on hospital days one, two, and three.
• 15:50
  SPEAKER_00: We should be doing things that are likely to benefit uh all of our patients, not just uh giving the impression that our goal is to reduce rates.
• 15:58
  SPEAKER_01: Great.
• 15:59
  SPEAKER_01: You both bring up some great points.
• 16:01
  SPEAKER_01: It might be helpful next for us to discuss how these considerations that have been brought up have resulted in change at your individual institutions.
• 16:10
  SPEAKER_01: And maybe you can also talk about the role of the electronic health record to optimize testing of C diff.
• 16:18
  SPEAKER_02: I want to comment on some things that were just said, many of which I actually agree with.
• 16:23
  SPEAKER_02: And I I do worry about some of the uh optics about having certain approaches to things that happen when they would count as a hospital onset, C diff as seal, and different approaches when they wouldn't.
• 16:34
  SPEAKER_02: But I can tell you how the process has kind of worked at uh my institution and uh as has been reported from multiple others at kind of Shady Spring Conference and in other forums.
• 16:46
  SPEAKER_02: So we had implemented a kind of lab algorithm, and there is a available kind of flow chart as you're thinking through C difficile, what are the things you ought to think about in terms of is this a clinically active infection?
• 17:04
  SPEAKER_02: And so there was a lot of education around that for medical, surgical, nursing, uh, and other providers in the hospital.
• 17:13
  SPEAKER_02: Then to back that up, we added whenever you order a C.
• 17:17
  SPEAKER_02: diffacil assay, it will come up with a best practice alert, which is just to remind you what those criteria are.
• 17:26
  SPEAKER_02: And on top of that, we have our infection preventionists actually review the cases each day before the C.
• 17:36
  SPEAKER_02: diffacile tests are run.
• 17:38
  SPEAKER_02: Now, you can always order an urgent C difficile test outside of the usual time when it's run.
• 17:48
  SPEAKER_02: Um, that just requires a conversation with infectious disease.
• 17:52
  SPEAKER_02: And even if we cancel, that we actually hold on to the sample and uh can run it later the same day.
• 17:59
  SPEAKER_02: So in the morning, the infection preventionists will come in, they'll review the new C.
• 18:04
  SPEAKER_02: difficile orders that have come in with an understanding that uh we'll make decisions on uh which ones are appropriate or potentially not appropriate by a one o'clock run.
• 18:16
  SPEAKER_02: And then all the cases that are kind of felt to not be appropriate will trigger a conversation with the primary team to get more information and for further education.
• 18:30
  SPEAKER_02: And if the team still wants to run, it will oftentimes uh trigger a conversation uh with myself or the other hospital epidemiologist uh just to understand.
• 18:42
  SPEAKER_02: And and oftentimes, you know, we will say, okay, uh that that seems appropriate or have further conversations.
• 18:49
  SPEAKER_02: But the goal is not to stand in the way of providers trying to provide the best care for their patients, but really to be an educational tool.
• 18:59
  SPEAKER_02: As we have done this, we have seen a reduction in our C to Facile counts or rates for the hospital.
• 19:08
  SPEAKER_02: And we've also seen a shift towards more of the cases that we're uh diagnosing being toxin positive rather than just PCR positive, which is not to say that we aren't identifying cases that are PCR positive, we absolutely still are, but we are looking at that shift to say, okay, we are identifying a larger proportion now that are toxin positive.
• 19:32
  SPEAKER_02: And while we recognize the sensitivity issues, we do think that that correlates with more clinical uh disease.
• 19:39
  SPEAKER_02: So that's kind of what we have uh done.
• 19:42
  SPEAKER_02: You know, what I will say is an example would be uh someone who has been on laxatives and develops some diarrhea, and the team says, Well, my real concern is this is new diarrhea.
• 19:54
  SPEAKER_02: They've been on the laxatives for a while, and their neighbor was just diagnosed with C defacile.
• 20:00
  SPEAKER_02: We would say, you know, that that seems like a valid concern.
• 20:03
  SPEAKER_02: Let's run that test.
• 20:04
  SPEAKER_02: So it's not a hard and fast, no, we will not.
• 20:07
  SPEAKER_02: It's often a conversation.
• 20:09
  SPEAKER_00: Yeah, and I think we've implemented some interventions, you know, very similar to those, although a bit less intensive.
• 20:16
  SPEAKER_00: Uh we put in place a CDF order set several years ago that provides guidance to clinicians on testing and treatment, guides clinicians to only order CDF testing if significant diarrhea without an alternative explanation is present.
• 20:30
  SPEAKER_00: And we did kind of implement this in conjunction with education of personnel and uh intermittent monitoring and feedback on the appropriateness of testing.
• 20:39
  SPEAKER_00: And we do that again intermittently, but we provide similar feedback on asking people to consider canceling a test after discussing individual cases.
• 20:48
  SPEAKER_00: Uh the one other point I would make, um which I'm sure is part of Michael's program as well, is we include nurses in all of the education and feedback that we provide because they have a major influence on appropriateness of CDI testing, uh similar to you know sending urine cultures, you're not really going to make a major impact without uh involving nursing staff.
• 21:09
  SPEAKER_00: And again, I think these types of um order sets are helpful, but you really do need that uh kind of personal touch where you're actually interacting with clinicians.
• 21:20
  SPEAKER_02: No, and I agree with that 100% the uh critical nature of involving uh nursing.
• 21:25
  SPEAKER_02: And part of that for us actually was kind of getting away from this historical perception that uh the olfactory diagnosis is accurate, and so we were able to kind of re-educate a little bit on that because a lot of this was, well, it smelled like C diff, but we had some data to kind of say that's that's not our our best measure.
• 21:45
  SPEAKER_01: Well, thank you so much, Dr.
• 21:47
  SPEAKER_01: Michael Calderwood and Curtis Domsky, for sharing your perspectives and experiences.
• 21:52
  SPEAKER_01: This has been a great discussion on the potential benefits of C.
• 21:55
  SPEAKER_01: diffacetyl diagnostic stewardship and the importance of pursuing this type of intervention for the right reasons with the right safeguards in place and really promoting that conversation.
• 22:05
  SPEAKER_01: If you're looking to expand your knowledge and diagnostic stewardship, then join us at the sixth international conference on healthcare associated infections, decennial 2020.
• 22:14
  SPEAKER_01: This conference will be held in Atlanta, Georgia from March 26th through the 30th and is co-hosted by Shea and the CDC.
• 22:22
  SPEAKER_01: Find out more and register at www.decennial2020.org.
• 22:27
  SPEAKER_01: This concludes the first episode of the Diagnostic Stewardship Podcast.