How to Plan for B. pseudomallei Exposure Cases - A Laboratory Perspective
Melioidosis is an infectious disease caused by the bacteria Burkholderia pseudomallei. In 2021, an intraoperative periaortic swab sample was confirmed positive for a Burkholderia species, and three of the thirty clinical staff-identified exposures were confirmed laboratory-acquired exposures. With the increased presence of B. pseudomallei and Melioidosis cases, laboratory workers are at an increased risk of exposure. This presentation will explain the role of laboratory professionals in detecting B. pseudomallei in clinical specimens and how to plan for possible exposure cases.
- Identify educational and other resources available through the OneLab Network.
- Identify the growth characteristics of Burkholderia pseudomallei.
- Discuss standardized laboratory tests used to isolate and identify Burkholderia pseudomallei.
- Recognize the challenges of identifying Burkholderia pseudomallei.
- Define high-risk versus low-risk exposure and the frequency of laboratory-acquired melioidosis.
- Explain the indication for post-exposure prophylaxis, and its efficacy.
Lisa Speiser, D.O.
Infectious Disease Physician, Mayo Clinic
Erin Graf, Ph.D., D(ABMM)
Director, Clinical Microbiology
Associate Professor, Mayo Clinic
CHELSEA PARSONS: Hello, everyone. Welcome and thank you for joining. We'll get started in just a minute. We'll give other attendees just a second to join in. We'll get started in just a minute. Thank you again for joining our OneLab Network event today.
All right, it looks like we've got a good amount of people in the room now. So let's go ahead and get started. Welcome, everyone. Thank you for joining. My name is Chelsea Parsons, and I'm a consultant with Guidehouse, supporting CDC'S OneLab Initiative.
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So let's go ahead and take a look at our agenda for the day. We're going to start with just introducing a new OneLab resource for you and go through today's presenters. Then we will go into our main presentation and finish out that Q&A that I mentioned earlier. We'll have a couple of closing remarks before we close out, and that's when we will also give you the information for obtaining PACE credit for today's session.
So I will now be turning it over to our OneLab Network lead, Alicia Branch, to share some of our new and relevant resources and introduce us to our speakers. Alicia?
ALICIA BRANCH: Thanks, Chelsea. As Chelsea said, I want to take a moment to introduce you to some new CDC Onelab REACH training courses. Hold on. Hold on, Chelsea. I actually don't have anything for-- I have the wrong thing pulled up. Hold on just one second.
CHELSEA PARSONS: I think we'll just introduce the Partner Toolkit.
Think Alicia might be having some Wi-Fi technical issues today. But we are going to introduce you the OneLab Partner Toolkit. So it's now updated with all OneLab elements. You'll see a link dropped in the chat for that. And so what's in the toolkit, it's email templates, social media texts and images, postcard, and blog posts.
And we invite you to use the customizable materials in the toolkit to tailor and share information about these resources with your networks. So you can go into the link in the chat and download and share those materials today. So, Alicia, if you're there, we'll go into the disclaimer slide.
ALICIA BRANCH: Can you hear me?
CHELSEA PARSONS: Yes, I can hear you. Yes.
ALICIA BRANCH: Sorry about that. Yes, I'll go through two disclaimers and then introduce our speaker for today. The slides may contain presentation material from panelists who are not affiliated with CDC. The presentation content from external panelists may not necessarily reflect CDC'S official position on the topics covered. Next one. CDC, our planners, and our presenters wish to disclose that we have no financial interest or other relationships with the manufacturers of commercial products, suppliers of commercial services, or commercial supporters.
And I am pleased today to introduce-- we actually have two speakers. The first speaker is Dr. Lisa Speiser. She's an infectious disease physician at the Mayo Clinic in Arizona and the Medical Director of Infection Prevention and Control. Her areas of interest include emerging infectious diseases and hospital-acquired infections.
Our second speaker is Dr. Erin Graf. She is an associate professor and co-director of microbiology at the Mayo Clinic in Arizona. Erin is a board-certified medical microbiologist. Her research interests include the application of next-generation sequencing, genetics, diagnostic and epidemiology investigations, as well as emerging rapid diagnostics technologies paired with diagnostic stewardships. Our speakers for today is, again, Dr. Lisa Speiser and Dr. Erin Graf.
LISA SPEISER: All right, good morning, and I'm just going to go ahead and share my screen here. And you can hear me OK?
CHELSEA PARSONS: Yes, we can.
LISA SPEISER: Perfect. Thank you, and you can see my slides. Wonderful. Well, good morning. Thank you for having me. It's an honor to be here. I'm here today to talk to you about how clinical and public health laboratory professionals should plan for possible Burkholderia pseudomallei exposure and cases. I am Dr. Lisa Speiser. And with me today, I have my associate, Dr. Erin Graf. We'll go ahead and get started.
All right, so throughout this talk, you'll learn to identify the growth characteristics, discuss standardized laboratory tests used to isolate and identify, as well as recognize the challenges of identifying Burkholderia pseudomallei. We'll define the high risk versus low risk of an exposure and the frequency of laboratory-acquired melioidosis. We'll also explain the indication for Post-Exposure Prophylaxis, or PEP, and its efficacy. We have no financial disclosures.
So to start off with a little bit of a background, Burkholderia pseudomallei is an aerobic, gram-negative, rod-shaped bacterium commonly found in surface waters and muddy soils. It is transmitted primarily through direct inoculation with contaminated soil and water, particularly with skin abrasions. However, during the rainy seasons, the primary mode of transmission shifts from inoculation to inhalation. Ingestion of contaminated water, soil, contaminated food can also occur.
Melioidosis has a high risk of mortality, even when we're able to diagnose and treat it, and an even higher risk if it's left undiagnosed. The case fatality rate ranges anywhere between 10% to 40%.
Burkholderia pseudomallei is found in tropical climates and endemic to Asia, Australia, South America, and the Caribbean, with the majority of cases in Northern Australia and Thailand. However, as we learn more, we are discovering uncovered reservoirs throughout the world which make the boundaries of Burkholderia pseudomallei endemicity less clear.
Around a dozen cases are identified each year in the United States and have primarily been identified in travelers and immigrants from endemic regions. However, between March and July of 2021, the CDC confirmed four linked cases with two deaths of melioidosis in patients from Georgia, Kansas, Minnesota, and Texas. None of these patients had traveled to endemic regions. And based on whole-genome sequencing, this strain commonly came from South Asia. It was ultimately linked to aromatherapy spray sold at Walmart stores between February and October of 2021.
Burkholderia was also recently discovered in the environment along the Gulf Coast of Mississippi in the US around the homes of two unrelated residents who developed melioidosis. One was in 2020, and one was in 2022.
Although healthy people may get melioidosis, underlying medical conditions may increase the risk of disease. The major risk factors are diabetes, underlying structural lung disease, liver disease, chronic renal disease, thalassemia, immunosuppression, or malignancy. The incubation period ranges anywhere from 1 to 21 days, with a mean of 4 to 9 days. However, latent infections can reactivate after years.
The most common clinical manifestation of acute infection is pneumonia. Other sites of infection include skin and soft tissue, as well as the genitourinary tract. Bacteremic spread of the organism can result in clinical manifestations involving virtually any site. Over half of all patients are bacteremic, and up to a quarter can present with septic shock. Overall, mortality from melioidosis, again, ranges from less than 10% to over 40%.
Those with symptoms greater than two months are considered to have chronic infections, of which the majority present with chronic pulmonary symptoms and signs that may mimic tuberculosis, or with a nonhealing skin ulcer or abscess. Chronic infection is more indolent than acute, and it's associated with a 6.5-times-lower mortality rate.
Infection can also be latent, with subsequent activation analogous to tuberculosis. The longest reportedly latent period between exposure and development of melioidosis in a nonendemic region was 29 years. I'll turn it over to Dr. Graf.
ERIN GRAF: Right. Due to some technical difficulties, I get to present from Dr. Speiser's office, so bear with me as I get myself situated here. So hopefully, you got some excellent background from her on why this is such a serious infection and why it's really so important to the laboratory to be aware of the potential consequences of this pathogen. And also, the increase in cases, both through sources external to the United States but also sources local to the United States-- just awareness as this may become a more frequent laboratory infection.
So I'm going to take you on a bit of a story of what transpired within our laboratory here at Mayo Clinic in Arizona and our lessons learned that apply, not only to this particular pathogen, but some of the other really high-consequence laboratory exposure pathogens, including select agents.
So this is kind of the backstory of our exposure. This was a patient who had a specimen collected in the OR. It was sourced as an aortic tissue but also had a swab sent from what was sourced as an abscess. And that was received in the laboratory and plated for routine cultures.
It hit this weird time point where it was too young to be worked up on the day shift. And so it was subcultured and waited for appropriate workup the next day. We don't read cultures around the clock here and work them up around the clock. So that was part of the issue.
So at that time point, it was just a little bit before 18 hours. It was noted to have light growth, very tiny colonies, pinpoint colonies. And so I'll give an image of that here. This is not our actual image. This is one, I think, that is from the literature. But you can imagine it looked just like this at 18 hours. So it was pinpoint growth on both sheep blood and chocolate agars, and then even less growth on the MacConkey agar pictured there.
The technologist at the time really thought it was going to be a Pseudomonas. Whether it was a Pseudomonas aeruginosa, that was a weak-growing variant versus a nonaeruginosa Pseudomonas. That was really what she thought she was seeing on those plates, again, before 18 hours.
So the organism was placed onto MALDI with this assumption. So we used MALDI-TOF, as most labs do, for identification. And we use the clinical side of it, the FDA-approved side of it, not the research-use-only side.
However, I think at that point, she had no results and then pivoted over to the RUO side, which we sometimes do. Even though it's not validated, it can give us a little bit of a clue as to what it might be and then the steps we can take to work it up further. And at that point, she got an identification of Burkholderia thailandensis, which should set off hairs on the back of your neck to stand up because that is a common overlapping ID between Burkholderia pseudomallei. So that was kind of our clue that this was potentially a select agent.
So at this point, it was sent off to [? Public ?] [? Health ?] laboratories for them to do their work. There's a little bit more of a backstory to it, in that we did some basic biochemicals, and we thought we had actually ruled it out. It was catalase negative. And so if you read through some of the guidance on how to handle these from ASM and CDC and the APHL Laboratory Response Network.
Catalase is one of the tests that you can use. Unfortunately, in this case, it was catalase negative, which, really, that should have been a flag to us as, stop here. Don't go further. But in theory, we thought we had ruled it out, so it was a little bit more complicated of a story. So we eventually sent to [? Public ?] [? Health, ?] and so they deemed it Burkholderia pseudomallei.
So unfortunately, this led to exposure to three technologists in the laboratory. And I won't go into the details on that because Dr. Speiser is going to cover the exposure follow-up. But this was such a huge deal for our laboratory to have this exposure. We took it extremely seriously. And so as I said, Dr. Speiser will go into the prophylaxis and the serologic monitoring next.
But we did a risk assessment on some of our workflow processes. And this was done institutionally. So this was beyond lab. This was to the highest levels of Mayo Clinic. This was such a big deal, and it was so serious.
And so I want to just give a quick shout out because these slides are largely all borrowed from Jessica Larsen, who's our laboratory supervisor now. At the time, she was the lead technologist, and she was fortunate enough to present all of this data at the ASCLS annual meeting last year. So I just want to make sure I give her shout outs throughout this talk.
So as a result of some of the risk assessment that was performed, of course, one of the knee-jerk reactions is to go and update your SOPs. Are our SOPs robust enough? Did they have enough detail on how to suspect a select agent and how to rule something in or out or what the steps are to do?
So it's clear in this case-- and these were some pretty seasoned and senior technologists who manipulated this culture. It was clear to us that there just globally wasn't a ability to recognize these as potential select agents. So we modified our SOPs. We added a lot more detail and verbiage around and some images around what to look for.
But in the end, we realized that just updating SOPs and then reminding folks at huddle to read the SOPs and sign off that they read the changes is just simply not good enough. So we know this because we performed some competencies. So we did some fake test patient, select agent mimics. And then we participate in the College of American Pathologists Laboratory Preparedness exercises, which is meant to test this exact system. Their select agent mimics, or Pseudomallei can be one of the mimics.
And so we failed miserably. We had actually six new potential exposures. They weren't real exposures because these were all fake mimic of a potential select agent. But that just brought awareness to the fact that simply updating SOPs is not good enough. So we realized we really needed to do something different.
So I already gave a shout out to Jessica Larsen, but the rest of the team, Dr. Thomas Grys, who's my codirector, Barb Harris and [? Cassie ?] [? LaSalle, ?] who are supervisors for the laboratory, Jake Karsten, our safety officer, Joyce Lau, our chief team lead-- we all came together and said, we have to do something different. There's something wrong here, and we can't sleep at night with the potential for another exposure.
So we approached it in a quality framework. And so the first thing we did was sit together. And I'll say this happened kind of rapidly and ad hoc. It was not as formalized as this drawing makes it seem to be. But we were able to go back later and map this out in a visual way. But we went through every step of our laboratory processes, all the steps that happened from plating to culture reading.
And so, again, this is the work of Jessica Larsen. You can see pictured here, the steps that are in the purple boxes are the processing steps. And then the blue boxes and circles are the reading steps of things.
And so that's really where the plate manipulation happens on the benchtop. We do all of our processing and our plating inside a biosafety cabinet. So we felt like our processing team was really safe. But it's totally impractical to think about reading every single culture inside a biosafety cabinet. So we needed to find ways to do this kind of work safely when it's happening on the open benchtop.
And so we, again, honed in on the steps where the actual exposures occurred. So that visual inspection of plates-- if you're a microbiologist, you're used to pulling out your stacks and stacks of plates. And then you're just flipping through them one at a time, usually just immediately taking that lid off the plate and visually looking at what's going on the agar. So, boom, that's already an exposure in a sense because you're opening it up into the air. So that was one of the things we honed in on.
And then the biochemical testing and the identification on MALDI-TOF are big potentials for aerosolization. So when we're doing things like an oxidase or catalase, those are highly aerosol, especially the catalase. I'll get to that in a bit-- highly aerosol generating. And then MALDI as well, doing that outside the biosafety cabinet has a potential risk of exposure. And then setting up your McFarland for susceptibility testing-- that's usually done in an open tube, and you're vortexing it, so high potential for aerosol exposure there.
So we had a discussion around, OK, these are our high-point steps that we need to change the way that we do the work that we do. And what are some steps we can take to change the way we handle things? And so we did an impact-effort matrix, where we talked through some of the things that we could use as solutions.
So as I said at the beginning, one theory that [? Risk ?] actually came to us with was, well, we can buy you some more biosafety cabinets. Will that help you, if you can do all of your work inside a biosafety cabinet? I think anyone listening that's a microbiologist realizes that's just simply not practical. With the volume of cultures that we handle, we can't do all of that work inside a BSC. So that was kind of a high-impact potential, but the effort required to implement was extremely high.
We could purchase lab automation to screen our culture plates. And I'm going to come back to that at the end because that's actually something we ended up doing. And we thought it would have high impact. But in the end, it actually doesn't. So we'll come back to that.
What we kind of hovered around was the potential to keep the lid on for visuals-first inspection. So if we can retrain our techs to say, all right, I'm not just going to flip that plate and open it up and have a look the way that I'm used to doing. If I'm just going to keep that lid on for that very first look and if I can visually rule out a select agent, then I'm safe to go back to my usual workflow.
We could also tape all the plates to enforce that folks don't open the lid to begin with, but that just became completely impractical. And actually, taping and parafilming plates leads to contamination. We could put bright labels on all the plates as a reminder maybe based on specific sources, like an abscess or a respiratory source. But in the end, we felt like that would have extremely low impact on the situation. People would just start to ignore it.
And then, really, the primary goal of this was to take the lid-on method, so keeping the lids on the plates, and then put that into an education module to modify that workflow. And sometimes fear can be a really important factor in behavior changes, so putting in some scary real-life consequences to that education module. And so, again, a shout out to Jessica Larsen and then [? Jesse ?] [? Frank, ?] our education specialists [? II, ?] who were the drivers of this education module.
All right, so I'll move ahead and say that, again, we're focusing on this lid-on method to avoid that first step in potential exposure. And then we really don't have to worry about the subsequent steps. So we're probably overly conservative, and that was OK with us. We wanted to intervene at that moment of first opening the plate. And then if we can't rule out a select agent, we're not going to move forward with those potential other steps of risk, the biochemical testing and the MALDI-TOF.
All right, so just to show you a few screenshots of this education module-- and I'm going to give you a link in a little bit because this is actually accessible to everyone. So again, we approached this from the angle of being as conservative as possible. We wanted to make sure that if there was a potential select agent, we stopped before any further potential for exposure, so stopping before we did biochemical, stopping before we potentially did MALDI-TOF. We never wanted something to get on to MALDI and then realize, shoot, we didn't rule something out. So, again, probably overly conservative, but that was OK to us.
So here are a few images that are describing some of the old workflows versus the new workflows, again, just focusing on keeping the lid on the plate as we're examining the plates and then the features to look for, so that pinpoint growth on the chocolate and sheep blood agars.
And so this module, it walks you through potential scenarios. And it lets you pick and decide how you're going to handle something. So it has these features that are consistent with Burkholderia pseudomallei. And what are you going to do with it? Are you going to-- what biochemicals are you going to perform? And then at what point are you going to intervene with the state public health laboratory?
And so one of the fun things that they put on here was how a catalase test works. So you can see here is an isolate that is run on a catalase test. And you can see the aerosolization that takes place in the culture growth. And then here's showing the method of keeping the lid on the plate. That went through really fast, so I'll play that-- see if I can go back and play that one more time for you.
But, yeah, here, you can see the catalase test is resulting in growth on that plate sitting on top, showing you how it actually aerosolizes and then creates an exposure for you as the individual. And then there's the keeping the lid on and investigating the plate. So again, major shout out to [? Jesse ?] [? Frank ?] and Jessica Larsen and all the individuals who helped with that.
So to make it even more fun, Jessica and [? Jesse ?] created a choose-your-own-adventure method here. So you could basically get to pick the path that you go down. And there used to be books that did this. And now you can actually do this on Netflix and other systems, where you can choose where the characters go or where the story goes.
So you can do that with culture plates. You can decide, are you safe to work this up on the benchtop? Or are you going to go into the biosafety cabinet? So you get to choose your own adventure there. And if you choose the wrong thing, it might tell you, oop, incorrect. Now you've accidentally exposed your coworkers and yourself, and here are some steps that are going to happen and some fun things about, here's how different antibiotics can have an impact on you.
We all think, OK, I had an exposure. I'm just going to take a course of antibiotics. I'll be fine. But there's some nasty side effects. Dr. Speiser can speak to that in a little bit. So we never want to get to that point of just saying, well, it's OK. I had an exposure. I'll just take some prophylaxis. It's really not trivial.
And so it gives further explanation and guidance. If you get something wrong, it doesn't just leave you there with, hey, you're wrong. This happened. It gives you some guidance and explanation behind that.
And so it gives you a score at the end as well. And so you can go back and redo some of the scenarios. If there's one that you're really struggling with and you need to keep going back and going through it, it gives you that opportunity. Yeah, so ultimately, it likes to remind you, you must live with your choices. So again, that exposure to yourself and to your laboratory coworkers, really hammering home a little bit of that fear, change motivation.
So here is the website for the module. I think they're going to paste it as well in the chat or the Q&A box. And so, again, just a shout out to the content creators. They're amazing people at Mayo Clinic.
So Jessica's goal with this was to not only have everyone take that module and complete that module, but then to actually see what kind of changes came into place as a result of that module. So she and her team sent out fake patients. So we tried to mask these as best we could as fake patients. It's actually hard to do in the system.
But we created fake patients and sent them out and tested the tech's ability to recognize them as a select agent. So did they recognize with the lid on that there was a suspicious growth and then immediately bring it into the biosafety cabinet, consult the director on service during rounds, and then, if necessary, refer to [? Public ?] [? Health? ?]
So 100% success rate, 10 out of 10 techs had great recognition, no potential exposures. And you can see here the different organisms that we threw at them. They're all pretty much mimics of Burkholderia pseudomallei. That was really our focus at the time because of that exposure. So we were really proud of the work that the team did on this. Yep, and so 100% worked up in the BSC, 100% director on service notified.
So we also monitored our real-time clinical isolates, so meaning we got an isolate through an actual patient. And there was concern that it was a potential select agent, again, mostly focused around pseudomallei. What did we end up finding when we sent it to [? Public ?] [? Health? ?]
So I will say, this is a really important partnership, and we're lucky to have a great team here in Arizona. And so I encourage those who are listening to really interact with your either local or state public health laboratories around this topic because what happened was after the module, our rate of submission of isolates to them for rule out dramatically increased. And they came back to us and said, hey, what's going on? Y'all never used to send anything, and all of a sudden, we're getting a couple a week, maybe one a month. Is there something we can do to help you rule these out faster?
So we talked to them about what we had available on site. So for those of you that use MALDI-TOF, you're probably familiar with reducing a lot of your biochemicals. So we don't have urea slants, for example, anymore. We don't really use them for anything. So we had to talk through with the state lab what we have access to and what we don't have access to and what is reasonable to bring in. If we're only going to use it once in a blue moon, things like a colistin disk, that's just not something we maintain in the laboratory.
So in the end, they were fine with it. Once they understood the backstory and once they understood what our goals were, they were actually fine with doing all of this work.
And so here, you can see the spectrum of organisms that we sent, where we couldn't rule out a select agent. We couldn't rule out Burkholderia pseudomallei specifically. So it's a range of different bugs. It's not one particular. So it's lots of small, gram-negative bacilli. In the case of Pseudomonas species, those can be really tricky.
But we also had some Pseudomonas aeruginosa that tricked us that were really pinpoint growers, maybe weren't growing well on Mac, tiny on the gram stain, so just to show the point of, it's not one thing that's going to cause you to be concerned. It's a variety of different organisms that might raise concern.
So as I said, one of our potential solutions was to implement automation. And we were really excited about the safety that might come along with having a completely closed system. So here, one of our lead technologists, [? Sentayu ?] and Felicia Rice, our technical specialists [? II-- ?] they're doing the first digital read of cultures on this system. And [? Sentayu ?] right here, he's just reading things digitally and making decisions about them without even manipulating the plates. And then if it needs a MALDI ID or further workup, he's pulling that off the line and the carousel here.
So we thought, OK, this is great. We're going to digitally see these things. Our Spidey senses are going to go off. That is a potential select agent. And then we'll be able to safely work with it from there.
Well, not so much the case. So I'm going to show you one image here. I grabbed a second one, but I didn't get to put it in. But we had two recent-- I don't want to call them failures, because they think that's unfair, but two instances of lack of recognition.
So the first one on the left here, I bet many of you can guess what that is. This was actually a Laboratory Preparedness Exercise that has already been created and all of that. So I can share that openly. This is an attenuated strain of Bacillus anthracis. And it really has the classic morphology of the ground-glass colonies, no hemolysis. And then you can see these Medusa-head projections more prominently on the chocolate side.
So with the [? WASP ?] system, or with our automation system, we've moved to these chocolate sheep blood [? biplates. ?] And that's really to save space on the incubator and to speed the imaging. But that comes with some consequences too because we're no longer routinely plating a MacConkey with everything.
So the other image I was going to show you-- you'll just have to picture it in your mind-- looked just like the Burkholderia pseudomallei pinpoint growth on both the chocolate and the sheep blood sides of the agar but no MacConkey to compare it to. And that technologist validly thought, well, this looks like a coag-negative staph to me-- we get pinpoint coag-negative staph sometimes-- and was ready to pull it off the automation line in [? MALDI, ?] just like this plate here on the left.
So it really brought some awareness to us that the sustained safety requires constant probing and testing of the system. So we sent out additional fake patients for our techs to recognize. And fortunately or unfortunately, word kind of got around, and our ability to hide them as fake patients was a bit uncovered. So we didn't really get to robustly test the system the way that we wanted to. But at least the hyperawareness is kind of reminded.
So I think that's where we're at right now in this cycle of how frequently do we need to do this kind of fake patient testing, just to keep this front and center in people's minds, because our likelihood of seeing an actual pseudomallei-- while extremely low, we never want someone to miss that recognition or that first moment of realizing that this is something concerning.
All right, so again, one huge shout out to all of the microbiology team for participating in all of this. And then I'm going to turn it back over to Dr. Speiser.
LISA SPEISER: All right, thank you, for that. That was fantastic. All right, so I'm going to go over the risk assessment and exposure evaluation. So risk factors associated with Burkholderia pseudomallei in laboratory work are listed here. Exposure to aerosols represents the greatest biohazard because it can result in inhalation, ingestion, and mucous membrane contact. The same risk factors for naturally acquired infection are also used for the risk assessment of laboratory staff.
If there is planned work with Burkholderia pseudomallei, baseline serum samples should be obtained from all workers and logged and stored at negative 80 degrees Celsius in a secure location. And these are only to be tested in the event of an exposure. Staff with risk factors for melioidosis should also be informed of their increased risk. And it should be formally explained and documented, and alternative work options should be discussed and provided when requested. In addition to standard precautions, any staff member who is working with this agent with identified risk factors should also be investigated for infection if they have a febrile illness.
So immediately following an exposure with Burkholderia, the site of contamination or inoculation should be washed thoroughly. And the designated safety officer for the lab should be notified. Again, high-risk exposure includes inhalation, inoculation, or aerosols into the eye, but all exposure should be evaluated.
After exposure, either the supervisor or staff member should describe the species and susceptibility pattern, as well as the type of exposure. The exposed staff member should be interviewed regarding drug allergies and current health status, including risk factors for melioidosis. They should also be placed into either a high-risk or a low-risk category.
So human data is lacking for Post-Exposure Prophylaxis, or PEP. In animal models, post-exposure prophylaxis has been shown to effectively prevent acute melioidosis if it's administered within 24 hours of exposure. However, it does fail to prevent latent or persistent infection. Nonetheless, consensus recommendations are to offer post-exposure prophylaxis to all employees with high- and low-risk incidents regardless of the predisposing risk for melioidosis. And a discussion around the risks of PEP should be balanced against the risk of infection in any given incident.
So the recommendations are based on treatment efficacy of naturally acquired melioidosis. If susceptible to trimethoprim/sulfamethoxazole, and there's no allergy, then trim/sulfate is the first choice for PEP. If there is resistance or the patient is intolerant, the next best choice is doxycycline or amoxicillin/clavulanic.
Doxycycline has been used in laboratory exposure and, in experimental mouse models, has been found to be more effective than amox/clav for PEP. However, the data for treatment favors amoxicillin/clavulanic. Doxycycline monotherapy is associated with higher rates of relapse and treatment failure compared to conventional oral combinations. Based on expert consensus and the incubation period, three weeks of PEP is recommended. Fluoroquinolone should not be used for PEP because their use in treatment of melioidosis is associated with a high failure rate.
Once an isolate has been identified in the lab, susceptibility should be obtained. Meropenem and ceftazidime are used in the treatment of melioidosis. Trimethoprim/sulfamethoxazole, doxycycline, and amoxicillin/clavulanate, as I had just discussed, are used for PEP. The information should be held in a record and immediately available to safety and medical staff after an exposure event.
Particularly important is when working with isolates from Asia because approximately 13% of Thai isolates are resistant to trim/sulfa. Trimethoprim/sulfamethoxazole should be tested by eTest or another reliable MIC-based method, as this testing to determine susceptibility of Burkholderia pseudomallei is unreliable and should not be used.
Proposed exposure-monitoring staff members should self-record their temperature twice daily for 21 days and report any fever, cough, or inflammation at the site of known inoculation. This should prompt further investigation with blood, sputum, and urine cultures.
A sample of serum should also be taken on the day of exposure, as well as at weeks 1, 2, 4, and 6, and tested for the presence of antibodies. Those who come from or reside in an endemic region may already have antibodies. There is no evidence to guide the interpretation of a series of titers after exposure. However, a rise in titer is likely to indicate a new exposure.
Based on expert consensus, if a worker seroconverts after laboratory exposure, further clinical evaluation and extended course of antimicrobial drug treatment is recommended. In persons who seroconvert but remain asymptomatic and culture negative, the PEP agent should be continued for a total of 12 weeks.
So laboratory-acquired melioidosis is extremely rare. There have only been two reported cases prior to 1981 in the United States. The first case, in 1966, was a bacteriologist studying Burkholderia pseudomallei, who acquired infection after her centrifuge developed a leak. And the concentrated suspension of organisms sprayed all over the walls and benches in her lab. She then used her bare hands to clean up the mixture of the media and organisms and then developed an ulcerative lesion at the base of her right index finger. This was followed three days later by chills, fever, malaise, as well as tender lymphadenopathy and pleuritic chest pain.
The second case occurred in 1980 in a lab tech who aerosolized blood and sputum specimens taken from a 29-year-old Vietnam vet with recurrent cavitary pneumonia. This was done outside of the biologic safety hood in an open-flask system.
And that is all we have. Thank you so much. I'm going to stop sharing my screen. Oh, thanks.
ALICIA BRANCH: Thank you. I'll see if my internet will stay connected. We'll go ahead and take some questions. If we do not get to answer your question during our Q&A session and if you have not submitted your question anonymously, we will do our best to respond via email after today's event. If you have any questions after today, please feel free to email the OneLab inbox at email@example.com.
OK, we have about 15 questions. And I will start with the first one. "Could you repeat the results from the MALDI RUO library?"
ERIN GRAF: No. So again, our goal is to ensure-- [CLEARS THROAT] Sorry, a little bit of cough going on. Our goal is to ensure that we are never going to MALDI-- thank you-- never going to MALDI because of that potential exposure.
So we had some discussions around-- one of the suggestions was to bring in the-- I think CDC has a library, a select agent library, which contains spectra for pseudomallei. For us, that was not a direction we wanted to go. First of all, we wouldn't ever be able to validate that. And second of all, even formic acid extraction or ethanol-based extraction, not so much for pseudomallei, but for anthracis, has been shown to be not 100% effective at killing that potential select agent.
So again, for us, our view was we want to stop at the point of recognition and never get to the point of doing MALDI. So validating all of that type of library, I think for our reference laboratory, where maybe you're handling gazillions of isolates-- it could make sense for a reference laboratory to have that clue or to have that information. But for a laboratory like ours, we never want to get to the point of MALDI. So, yeah, once we got that ID, we wouldn't repeat it because we would never want to lead to an additional exposure.
ALICIA BRANCH: I'll go ahead and ask this one. So for your MALDI, your results, did you upload the isolates to the micro net?
ERIN GRAF: I don't know what that is, so I'll have to educate myself on that. We use the, as I said, the FDA-clear side of the Bruker library, but then we did run it on the RUO side. So I'm not familiar with pulling that spectra off and then uploading it. I guess we might still have that file saved somewhere, and we might be able to do that, but I'm not familiar with that. So thanks, I'll have to look that up.
ALICIA BRANCH: OK. We can actually probably share information with you.
ERIN GRAF: Great.
ALICIA BRANCH: This one is probably for the Dr. Speiser. So what constituted the exposure of the three lab techs?
LISA SPEISER: Yes, that's a great question. So we had three exposures, one that was high risk, in which laboratory technician had prepared the specimen outside of the BSC, essentially aerosolizing the contents in preparing it, also with underlying risk factors for melioidosis. So that was our high-risk exposure.
The other two, which, after discussion with our local health department, had opened the plates outside of BSC as well. There was some question if the plates had been sniffed or not. But essentially, those had constituted low-risk per our local health department.
ALICIA BRANCH: Well, this is a good segue into this next question. "Does wearing a surgical mask minimize the exposure risk when reading plates?" [LAUGHS]
LISA SPEISER: Certainly, yes. So that was also something because, at this time, we were still universally masking for COVID-19. So certainly, that's an excellent question because people were wearing surgical masks when they were analyzing these specimens. And so I believe, in these cases, that one high risk and those two low risk were also wearing surgical masks in those instances. But nonetheless, we still consider them to be high risk and to low risk and then had discussion with post-exposure prophylaxis for all three of them.
ALICIA BRANCH: OK. Condensation on the plate would not allow for visible examination of the plate. How can we handle that aspect?
ERIN GRAF: Yeah, that's exactly why that taped plate idea or the parafilm-sealed plate idea was kind of a no-go for us, because that is what can lead to a lot of condensation. Honestly, it hasn't been an issue for us. So I would argue that if you are examining your routine bacterial cultures in 18 hours or even 48 hours, because some of these take that long to grow, and you have significant condensation, I would check your system there, because you really shouldn't have significant condensation without having taped plates.
Like, that happens in mycology when all the plates are taped. And you have to tape the plate and tap it down to eliminate some of that moisture. But, yeah, that shouldn't be happening in your routine cultures.
ALICIA BRANCH: This is a good one also. "Is there anything that the physician should do in looking to alert the lab of a possible case?"
LISA SPEISER: Absolutely. So if there's a clinical concern for Burkholderia, so if a patient has a history of coming from an endemic region or traveling to an endemic region-- which, again, it goes into-- there's a lot of uncovered reservoirs that we're finding more and more. We felt initially that there was no Burkholderia in the United States, but that turns out to not be true because now we're detecting Burkholderia in the United States and having increased number of cases.
But if someone has a clinical concern for either epidemiologic risk for melioidosis or a clinical syndrome that's concerning for melioidosis, then they should certainly be alerting the laboratory staff. And so it's a little bit more challenging because we're not considered an endemic region. So we don't think about it as much, which is why we want to start educating clinicians as well as laboratories that this is something to start thinking about when you are seeing these patients.
ALICIA BRANCH: OK, we'll take a couple of more questions. This one says, "The lid on the process seems on the surface to reduce the chance of aerosol exposure. Do you have any objective data with controlling experiments? We have completely ruled out a no-chance of aerosolization, even when plates are moved around and handled on the bench, even with the lid on."
ERIN GRAF: Yeah, good question. No, we don't have any objective data to prove that. Yeah, it's more of just a, I guess, educated assumption that not opening that plate and not sticking your face into it. And, for the record, sniffing is not a thing anymore, but I know that gets referenced a lot, and sometimes we use it for teaching purposes.
But just opening that plate, I think it's more the potential that, in that moment of opening, it may not be an exposure, but should you drop, it, should something happen, it's now open and available to be inhaled. But with the lid on, I see your point. Like, if you're jostling plates around, that seal is not 100% airtight.
ERIN GRAF: I don't know. Do you have any thoughts on that, Dr. Speiser?
LISA SPEISER: No. Yeah, I think I'd agree with what you just said.
ALICIA BRANCH: Sounds like graduate student project.
LISA SPEISER: Amen, exactly. Yes, yes.
ALICIA BRANCH: I think the rest of the questions, we'll send them to you all after the presentation. And we can have you answer them offline, and then we can send them out to the participants.
LISA SPEISER: Sounds good. Excellent.
ALICIA BRANCH: Thank you again for joining. I know I kind of reached out to you cold turkey, so I'm so happy that you were able to actually join and present for us.
LISA SPEISER: Absolutely. It was a pleasure being here. Thank you so much for inviting us to come speak about this. All right, thank you so much.
ALICIA BRANCH: Thank you.
LISA SPEISER: Bye-bye.
ALICIA BRANCH: We are offering 1 PACE credit for today's webinar. To receive PACE credit, you have to visit the link and use the passcode in the chat to complete the evaluation within two weeks. You'll receive an email containing these instructions if you miss the link and the passcode. As a reminder, the slides with the links will be posted at the reach.cdc.gov/onelabnetwork within the next two weeks.
And next slide, please. And, unfortunately, we had to actually change the 2023 OneLab Summit to April the 16th through the 18th, 2024. But what I'm happy to announce is that we actually moved it to the Medical Laboratory Professionals Week, or better known for laboratory professionals as Lab Week. So I am happy that we were able to move it actually to the Lab Week so that we can celebrate our medical laboratory professionals.
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