Episode Summary

From antifungal resistance to disaster microbiology and tales of visible mold growing across the skin of patients following a tornado in Joplin, Missouri, Dr. Shawn Lockhart, Senior Clinical Laboratory Advisor in the Mycotic Diseases Branch at the CDC talks all things fungi—complete with references to pop TV shows and the recently released 7th Edition of Larone’s Medically Important Fungi.
Subscribe (free) on Apple Podcasts, Spotify, Google Podcasts, Android, RSS or by email.

Ashley's Biggest Takeaways

  • Fungal infections are less common than viral and bacterial infections.
  • However, infection is often serious in immunocompromised individuals and those with underlying conditions, who are most vulnerable to infection.
  • The most common fungi encountered in the lab is Candida. Candidemia is one of the most common bloodstream infections in intensive care units (ICUs) and is likely underdiagnosed.
  • The second most common fungal infection encountered in the lab is probably Aspergillus, which is especially common amongst organ transplant patients and patients undergoing chemotherapy.
  • Pan resistance has been observed in Candida auris isolates.
  • At this time, C. auris is an almost exclusively hospital acquired infection (HAI).
  • Similar to other Candidas it infects from the outside in—entering the body from the skin through various central lines, feeding tubes and/or ventilators.
  • 5-10% of patients who become colonized by C. auris go on to develop a bloodstream infection.

Featured Quotes:

Probably the best part about my job is there is no typical day in the life. Part of being the senior laboratory advisors is I respond to everything. So, I receive questions from other clinical microbiologists either at the state level, the hospital level. I answer calls, I answer emails, we respond to outbreaks, I help guide the research. One of my current loves of my job, one of my emphases right now, is on capacity building, and especially international capacity building. So, I do spend a lot of time conferring with my colleagues literally all over the world leads to a lot of very early morning calls.

When I was a Ph.D. student, my mother-in-law, who suffered from a congenital gastrointestinal disorder, had been in and out of hospitals—she'd had most of her small intestine removed. And of course, that leads to a lot of different infections. And she ended up getting systemic candidiasis. And it caused massive organ failure and ultimately led to her death. And I had been working on Saccharomyces cerevisiae at the time. And when that happened, you know, I was bitter and angry, and I decided I was going to take that out on Candida. So, I began looking for a postdoc studying in Candida, and I ended up at the University of Iowa.

But, you know, I started out as a research scientist, and I spent 15 years doing basic research, or 13 years doing basic research. And then I just realized, kind of mid-life, that this wasn't really fulfilling enough. And, you know, I want to emphasize, it's never too late to decide that you might want to try something different. So, at the age of 40, I moved over to the hospital and did a 2-year clinical fellowship, because I wanted to be closer to patients and patient outcomes. And from there, I ended up at the CDC.

It was basically starting all over again, I had not had a micro class in 17 years. And you know, you do a clinmicro fellowship, you study everything, not just yeasts and molds. I had a very, very steep learning curve, but one of the things that we did was go on rounds with the ID team. And I've never done that before. And one of the very first rounds I went on, we saw a patient who was 21 years old and was going to die, probably that evening, of an infection that he got from literally just going out and drinking a little bit too much.

And man talk about an impact. You know, you see these patients, and that just hammers home, somebody's on the other end. And you know, your job is to be there to help them, and it really helps to focus your work and to make your work more fulfilling knowing that you're there for these other people that need your help.

Fungi aren't considered the way bacteria and viruses are because the infections aren't as frequent. And normally, healthy patients don't get fungal infections, at least fungal infections that are beyond the superficial. But that makes them especially disturbing, because the people who are susceptible to fungal infections are the people who already have serious underlying conditions, and that makes them less likely to survive a fungal infection.

A lot of times people don't think fungi. They think fungus after they've ruled out a virus, after they've ruled out a bacterium. And, at that point, a lot of times it can be too late. So, one of the big emphases that we've had at the for the last maybe 10 years, is just think fungus. We tell everyone, “Think fungus, think fungus. Have that in your differential.” Because if you're going to treat your patient, you want to get that empiric therapy started as soon as possible.

One of the biggest problems with diagnosing fungal infections, and another one of my emphases is, there are very few tests that are available—at least very few FDA approved tests. And that's another point of emphasis right now.

We have a brand-new group called the Fungal Diagnostic Laboratory Consortium, or SDLC, who got together in the last 3 years, just to try to push forward diagnostics for fungi.

You know, a company doesn't want to invest millions of dollars in a test that's only going to be run 1000 times a year. And so, we have trouble convincing them that their test will be used that there are enough patients to make it profitable.

There are some companies that have jumped in with both feet, despite the fact that they know they're not going to make a lot of money on their tests. We're really thankful for companies like that. But right now, not enough of them exist.

Antifungal resistance was my emphasis during my clin micro fellowship. Overall, antifungal resistance, at least acquired antifungal resistance, is relatively rare. In Candidas, it tends to be around 7%, or so. But what we're seeing now is this rise in a brand-new bug called Candida auris that very easily acquires resistance. And we've even seen pan-resistance in Candida auris isolates. It's something we've never seen before; we've never experienced before. And yet, here it is, all of a sudden. It's literally spreading across the world. It's spreading across the United States. We add new States every year, and that's something we're not used to seeing.

The other thing we're seeing in the U.S. right now is resistant Candida parapsilosis. And it tends to be single clones that rise in a geographic area and spread hospital-hospital. We don't know how or why yet, but that's something that we have an interest in.

The other bit of acquired resistance that we've never seen before is azole-resistant Aspergillus fumigatus. And that's caused by the use of azole antifungals or fungicides that are sprayed on agricultural fields.

In the U.S., we're using 4 times as much fungicide now as we were using 5 years ago. We know that azole-resistant A. fumigatus is in the environment, and as we keep spraying these fungicides, we are selecting for these resistant clones. And there doesn't seem to be a fitness cost to carrying this resistance. So, every year in these fields a higher and higher percentage of the azole-resistant Aspergillus emerges over susceptible Aspergillus.

We catch Aspergillus from the environment—the spores are literally all over us. You can stomp on your carpet in front of you right now. And I guarantee you, you will be spreading, Aspergillus fumigatus spores, they're just ubiquitous. As we keep selecting for resistant strains, we keep producing resistant spores. And we're going to see more and more patients that show up at the hospital with an already resistant case of pulmonary aspergillosis.

One of the things that I've emphasized to colleagues of mine who are teaching courses [on fungal identification] is to show them what they're actually going to see; show them a crappy slide where you have to hunt and peck for that 1 Candida. Because that's the reality of what they're seeing in their laboratories.

My favorite saying, I use it in every lecture I ever give is that molds don't read books. So, you know, just because it says it's yellow in a book, and you see it's tan on your plate, doesn't mean it's not what you're looking for!

So, for this edition, we tried to leave what Davise Larone had done as part of her legacy. We didn't want to make any radical changes because she did such a fantastic job of putting together this textbook. So, there weren't a lot of radical changes. We will, over time, start changing the pictures—this is hopefully the first of many new additions that we're going to have.

But one of the newest things that's in this [edition of the] book is taxonomy notes. People suffer so much through all these taxonomic changes that are going on in fungi—the names seem to be changing on a daily basis. And so, we tried to include old names, new names, possible names, anamorph names to the teleomorph names, so that you could look any 1 of those names up in the glossary, and it would take you to the current name of that organism. It doesn’t matter whether you have an old name or a new name, you'll be able to find what you want.

Having a good mentor, talking to your boss, or your laboratory director or you professor, and telling them what you're interested in and getting their feedback, I think is really important. You know, they've been through it; they've done this; they know how to pursue it. Doing it on your own…, yeah, you can do that. But there are so many resources, and people are afraid to reach out. I was afraid to reach out. I didn't want to bother a professor. But it was the best thing I ever did. And so, I encourage people, overcome your shyness. Go to your mentor, go to your professor, talk to them about what's out there and what might interest you, and listen to their feedback.

Links for the Episode:

Since its first edition, this seminal text has been treasured by clinicians and medical laboratory scientists worldwide. The 7th edition carries forward the longstanding tradition of providing high-quality content to educate and support the identification of more than 150 of the most encountered fungi in clinical mycology laboratories.

Get your copy today with $1 flat rate shipping within the U.S. or order the e-book! ASM members enjoy 20% off at checkout using the member promo code.

Let us know what you thought about this episode by tweeting at us @ASMicrobiology or leaving a comment on facebook.com/asmfan.

Shawn Lockhart