Diagnosis: TB or not TB?

More episodes in the Science Sound Off Podcast

We sit down with Jeffrey D. Cirillo, PhD, a Regents' professor in the Department of Microbial and Molecular Pathogenesis at the Texas A&M College of Medicine, to discuss his work on diagnosing diseases like tuberculosis quickly stopping the spread of the infection.

Episode Transcript

Christina Sumners: Welcome to Science Sound Off. I’m Christina Sumners.

Tim Schnettler: And I’m her co-host, Tim Schnettler.

Christina Sumners: And we’re here today with Dr. Jeff Cirillo. He is a Regents professor at the Texas A&M College of Medicine. Welcome to the show.

Jeff Cirillo: Thank you. It’s great to be here.

Christina Sumners: So tell our listeners just a little bit about yourself. What do you do?

Jeff Cirillo: Well, as a professor at the College of Medicine, I spend a lot of time working with medical students, both interviewing and lecturing to medical students. My area of expertise is infectious diseases, so I do research as well in infectious diseases, and the focus has been on respiratory pathogens since my graduate work, and that’s now over 30 years.

Christina Sumners: Wonderful. And so, what pathogens in particular do you focus on?

Jeff Cirillo: So the primary pathogens I’ve worked with for the longest are mycobacteria, which cause tuberculosis. So tuberculosis is currently the number one cause of death due to a single infectious agent worldwide.

Christina Sumners: Oh, wow.

Jeff Cirillo: So that’s why I’ve focused most of my effort on that one. But respiratory diseases in general are the number one cause of death in humans and animals worldwide. And so, I’ve focused on various respiratory pathogens that are important in different areas of the world. So, that would include Legionnaires’ disease, which is thought to be as much as 15 to 20 percent of pneumonia causes. But, that one is most frequently not diagnosed. So if you go to the doctor, they say you have pneumonia, that’s usually diagnosed by x-ray and they don’t say what agent is the causative agent for it. And so in those cases, of those cases, 15 to 20 percent is Legionella. They treat with the proper drug, so people get better, but they don’t oftentimes know what they have.

Christina Sumners: Oh, okay.

Jeff Cirillo: So it’s an interesting organism. It also causes Pontiac fever that causes a flu-like illness. So people think they have the flu, but in reality what they have is Legionella, and that’s in the water system. So people drink the water and they’ll get a flu-like illness and most of the time it isn’t diagnosed and we don’t even know it’s occurring. So, that’s why I’m studying it because it’s poorly understood and periodically it’ll cause an epidemic. We just recently had an epidemic in New York. About 20-something people got infected and two died. So, it’s a pretty important cause of infectious diseases. The biggest epidemics have been 700 people at once, and out of those, 10 to 20 will die. So it’s pretty scary to have it kind of sitting around and people always worry about new respiratory pathogens and this is one of those.

But we also work with staphylococcus, which causes respiratory diseases, pseudomonas, which is a primary cause of infection in cystic fibrosis patients, Klebsiella and streptococcus. Those are the primaries that we work with and most of the work in those other organisms is looking at new therapeutics because these are the super bugs that everybody talks about that are completely drug resistant, so we can’t use antibiotics against them. So, we’ve been developing antibiotics that can overcome all resistance mechanisms. So it’s a kind of an exciting area. We’re doing interesting things with molecular and nano machines and peptoids, so natural peptoids, the peptides that are used by your body to defend yourself. We modify those so that they’re more active and we get better killing of drug resistant bugs. So, those are some of the areas that we’re working.

Tim Schnettler: You mentioned some of the diseases and you mentioned flu, stuff like that people know about. Legionnaires’ disease is something people may not know a lot about. What was… Pontiac?

Jeff Cirillo: Pontiac fever.

Tim Schnettler: Pontiac fever. Tell us a little bit more about those because there may be listeners out there who don’t know exactly what those are.

Jeff Cirillo: So the most frequent epidemics we see in the U.S. with Legionnaires’ disease are point-source infections. So, there’s some site—it could be a water fountain or a hot tub, usually it’s an air handling system, an air conditioning system, and they’re always in large buildings. And so everybody works or lives in a large building, and those air handling systems have traps in them. They have corners and so on. And so those can trap bugs. And so when the bugs amplify out to large numbers, you can get a spray, an aerosol, that’s released that then is infectious. So that’s what you see.

So the, the most frequent, currently, we’re calling it, it’s what’s called traveler’s pneumonia. So people will go to a hotel and that hotel will have a problem with it and they don’t know about it. One of the things we’re working on, and we just published two papers on this just this last year, is the difference between the organism that makes you clinically ill and kills people and the one that just lives in the water system. And so if you go to water, so if we go to water in this building, we’ll find the bug, which everybody thinks is scary. But in reality, the majority of those bugs are not dangerous. They’re not infectious. And so we identify these sets of loci, sets of genes, in the bacteria that are responsible for causing death. And so if we take the one that doesn’t have these genes and put it into an animal model to see what it does, 100 percent will survive.

If we take the dangerous one, put that into an animal, all of them will die. And so that says, well these are the loci that we have to look for. So we can take molecular methods and look in the water system and say, this water system is dangerous, this water system is not. So this goes back to a real problem that people don’t know about. It is that OSHA and EPA, they have guidelines for how many of Legionella can be in the water system. So even though most people may not know about it, the government does know and they know that if there is an epidemic, they’re in trouble.

Tim Schnettler: Right.

Jeff Cirillo: And so they set a guideline of 1 to 10 bacteria in the water system. What’s the end result? The end result is nobody looks, right? Cause if you look, you’re going to find it. And then you’re going to have to mitigate, which costs hundreds of thousands of dollars, if not millions of dollars. And it’s not required that companies or hotels or anybody actually check. I’m not saying they should because the fact is most of the time it’s not dangerous.

Christina Sumners: Right.

Jeff Cirillo: So what we’re suggesting, what I’m suggesting, is a better way to go is to look for these loci, not just look for the bacteria. It’s a little bit more complicated test, a little more expensive to test, but at least then you know, “the dangerous ones there. Let’s mitigate.”

Christina Sumners: Right.

Jeff Cirillo: So you’re talking probably 1 percent of water systems that you would check that you’d find Legionella would actually have the dangerous kind in them. So it’d be a low percentage. The ones that cause disease in humans are actually a lower percentage and most will cause Pontiac fever. And I’ll be honest with you, even though you get the flu, really not a bad flu. Like, flu virus can kill you.

Tim Schnettler: Right.

Jeff Cirillo: But Legionella flu never kills a person. We have no cases that a person has died from Pontiac fever. And so it’s really a flu you want to have.

Tim Schnettler: If you have to have the flu, that’s the one you want.

Jeff Cirillo: Yes, exactly. I mean, nobody wants to be sick, but…

Tim Schnettler: Right.

Christina Sumners: But as far as they go, that’s not a terrible one.

Jeff Cirillo: No, no. Yeah, you’re not going to die. And we don’t even have cases of infants or children dying, elderly, no problem. So, it’s pretty innocuous overall.

Tim Schnettler: What’s the difference? I mean, you say…

Jeff Cirillo: We don’t know and that’s the problem, right? Because it doesn’t kill people, the government doesn’t put money into studying it. And so I don’t think anybody’s ever done a careful study to say, “okay, why?” We think, the theory is that it’s oral, so it’s drinking water most of the time. And so the one that causes serious disease, it’s usually higher temperature water. Our bodies are at about 37 degrees

Tim Schnettler: Right.

Jeff Cirillo: …centigrade, and so water systems are normally kept either hotter or colder than that. And so we think that the Pontiac fever form is more of a colder water. It doesn’t do well in human temperatures, and so it gets eliminated.

Tim Schnettler: Interesting.

Christina Sumners: Yeah, that makes sense. So you mentioned tuberculosis. I know you’ve done a great deal of work with that pathogen. Can you tell us a little bit about that and what you’re working on now?

Jeff Cirillo: Yeah, with tuberculosis, we’ve been doing a huge body of work on it. I was involved in the first experiments to do genetic manipulation, so molecular biology for the first time in the organism. And it’s funny because that organism was the first associated with being a microbe that causes disease by Koch in the 1700s.

Christina Sumners: The 1700s?

Jeff Cirillo: Yes. And so it was one of the first infectious agents discovered, but molecular biology wasn’t developed until basically the nineties. Late eighties, early nineties. So, during my graduate work we were able to get DNA in and manipulate the genome a little bit and start to study, why does this organism cause disease? And so, we’ve been focused a great deal on aspects of the organism that allow it to cause serious disease in humans. It’s similar to the work we do in Legionella. We’re curious, why does it kill people? So most of the time, perhaps you’re aware that 15 to 20 seconds a person dies of tuberculosis. So it’s very widespread disease. And one-third of the world’s population is currently infected with the bacteria.

Christina Sumners: Wow, one-third.

Jeff Cirillo: So if you go in a group, you’ll usually have somebody that has the bacteria inside of them. Yes. And so it’s really common, but we don’t, in most of those cases that have the bacteria, they’re not sick, and they’re not infectious either.

And that’s not necessarily a bad thing, right? They’re better protected against future infection. They’re better protected against death. So how do we keep the bacteria from coming out? So I’m very much interested in that. How does it get out of that site where it’s not causing disease and it’s priming your immune response? It’s actually a really good vaccine. It’s one way to think about it. It prevents you from getting infected otherwise.

So how does it go from one stage to another? And so we’ve been studying that for many years. And, in the course of that, we realized one of the biggest problems we have is there’s very few bacteria in the lungs during the initial infection. It only takes one to 10 bacteria to cause disease. So how do you find one bacteria? It’s a one micron particle. And so that’s about one-hundredth the size or one-fiftieth the size of a cell. So a single cell in your body. So you got to go through the entire lung and look for that smaller than a cell particle and maybe there’s 10 of them. Not an easy concept.

So what we started doing is developing ways that we could track the bacteria and follow them during disease in animals. Prior work, you had to kill an animal to know how many bacteria it had. Then, you know, chop up the tissue. You’d look at it and you say, “Okay, there’s, there’s one bacteria here” or “There’s 10 bacteria.” And actually one is almost impossible to measure. You just can’t consistently measure that.

But now, with like, sensing methods, we basically take the bacteria and we label them in different ways so that they’re fluorescent or bioluminescent. So they give off light or you can hit them with light and they’ll reflect a very, very bright color and you can make them different colors. You could make them green, you can make them blue, you can make them red. And it’s pretty cool. I mean you can do differentiation. So we talked about all the different pneumonia agents. The idea is then, we can label each one with a different color and then you go in, you have a scan with light instead of an X-ray, and by the wavelength of light you produce, you can tell which bacteria you have. That would be pretty cool.

So a single test that’s noninvasive, you don’t have to do anything. You don’t have to even expectorate into a cup like current diagnoses. You just pass in front of a camera. So that’s the ultimate goal, it’s a little bit idealistic. We’re not there yet. But what we’ve been able to do is we’ve been able to label TB with putting DNA in and with the new method that we developed, which is called reporter enzyme fluorescence, or REF. Using REF, we can take just a small molecule added to the bacteria and they produce a huge amount of light. And it’s catalytic because we’re using the enzymes that are present on the bacteria.

What that means is it can amplify the signal infinitely, and you’re using the energy that the bacteria produced to produce that signal. So there’s no limit, as long as the bacteria are alive, you’re measuring the fact that it’s living and it’s reacting with this molecule to produce more and more light. Makes it super sensitive and it really, it currently, it’s the most sensitive, it’s about a thousand fold more sensitive than any other method that we’ve found so far.

So we can find the bacteria now in the lungs. We’re not down to the one to 10 yet. We have done that with microendoscopic methods. So these are—it’s a fiber about the size of a hair and you take that and you put that in the throat and you touch the mucus in the back of the throat. So you can use a local anesthetic, that’s the idea at least—and we haven’t started a clinical trial with this, yet, so we’re doing this to animals—use a local anesthetic so the person doesn’t have a gag reflex and you just touch it with the hair. We can illuminate the entire lung with that single fiber, and then that reflects back to the hair. So we can then pick it up with a camera. We can detect one to 10 bacteria with that, which is really cool.

So we’ve reached that level of detection with the fiber. What we’d like to do is reach that level of detection with the whole animal. In preclinical models, we’ve been able to get down to about 100 to 300 bacteria in the lungs and we haven’t been able to do any better than that without the fiber.

So using the fiber, we’ve been able to get down to one to 10. So really our goal is to be able to do that in the preclinical model first, and then we’d like to go into pediatric populations and then adults if we can. We don’t know for sure whether or not we can go to an entire adult yet. But the modeling, so what we’re doing for the modeling, we’re working with the physics and biomedical engineering departments here to construct three dimensional models of the lung with a 3-D printer. And you take a CT of the lung and then you model the lung on that, but you have to fill it with mucus.

So what it turns out, the reason, and it is a very controversial theory right now because we’re using something called total internal reflectance to propagate the light. So in the field, there’s this dogma that in the lung, because there’s air and there’s tissue, light won’t penetrate. Well, it turns out that’s not true. And so right now we’re kind of developing the theory well enough to explain it to people because what’s probably happening, it works exactly the same as a fiber optic bundle for your cable in your house. It propagates the light by reflectance inside of the mucus in the lung, and so once it hits that mucus, it travels the entire lung and then comes back to the camera. So it stores the light, it doesn’t actually go away. And we figured this out based on some of our initial observations that when we illuminate in preclinical models, we find that the light doesn’t go straight through. It hits a membrane and then it gets reflected through the membrane. So it goes the path of least resistance to get to whatever infection is occurring.

So that allowed us to develop the systems that we’re working with. And then somebody came to me and they said, “Well, this is really exciting. You got a very sensitive way to detect bacteria. Could you do that in a cup?” I said, “We’re doing whole organisms here. This is much more complicated. And it’s so much more sensitive than that. Of course we could do a cup, why would you want to do that?” And they said, “Well, the diagnosis of TB is done with a cup.” And I said, “Oh, yeah.” I said, yeah, you know.

So the current diagnostics for TB, are if a patient comes into a clinic, anywhere in the world, meets a health care worker—oftentimes it’s not necessarily a clinic cause many of these don’t have infrastructure or power or air conditioning—they go in, they find a health care worker and they say, “I’m sick, I have this problem.” And they say, “okay, here’s a cup. Take it home. In the morning, that’s the best time to do this, expectorate into the cup.” You know you’re coughing anyway, that’s a chronic cough, that’s usually why they come in and they expectorate into the cup. And then they bring that back to the clinic.

So that cup basically tells you that’s the primary diagnostic method, and they use that. They take a wood stick, they put it onto a glass slide and they dry it and then that goes and they put it in a microscope and they can use a microscope without power. They use reflected light from the sun and they can stain it with a colored stain and they can determine whether or not you have TB. But the sensitivity, that’s like 90 percent of the world. That’s the method of diagnosis. Just realize very, very low tech. But it works. It works and so that’s a—but it’s very, very insensitive. It’s about 10,000 bacteria that they’re detecting. And so our threshold of detection in a cup with those same chemicals that we’re using to detect in a whole animal or a whole human, we can detect one to 10 bacteria in sputum

Christina Sumners: In the cup, okay.

Jeff Cirillo: In the cup. So very, very sensitive. Done all at room temperature, takes 10 minutes for the reaction, very, very fast. Even the slide, they have to dry it, they have to stain it, usually takes a couple days minimum, sometimes as long as weeks cause they want to take it to a microscopist that has experience in doing it.

And so we started developing and they say, “Well okay let’s think of a way that we can get this to places where they don’t have power,” and so on. And that’s when we developed, like, a reader for this that allows illumination and you just take a picture with your cell phone or whatever in a dark box.

So that’s currently where we’re at. We have a system where we can detect very sensitively, from sputum in a cup, in 10 minutes at room temperature. The cost is less than $2 per test. The readers, we were targeting less than $200 per reader, and the reader can be used infinite number of times.

Christina Sumners: Okay.

Jeff Cirillo: We assume it’ll have a lifespan, but it doesn’t have any moving parts. So we think it’ll last pretty well. One of the biggest issues we’re kind of coming up with now is, how do you control for the cell phone? Cause different people have different cameras.

Christina Sumners: Oh, sure.

Tim Schnettler: Right.

Jeff Cirillo: And we want to make sure that the analysis is consistent across the board. So we may have to dictate what type of camera, what type of cell phone can be used with the system. But we’re working on that. We want to make sure that we have a good battery life and that the reagents, this is like, the next step is that we can ship the kit to anywhere in the world cause there’s temperature fluctuations, right, and humidity. It’s very hot in a lot of areas of the world, and so want to make sure it’s stable and then we get consistent results.

But we just published the first clinical trial with this and that was a study in 160 patients where we compared it to the standard diagnostic methods of a smear microscopy and culture. And it showed a very high sensitivity and specificity overall.

We found, so the reason, I guess the biggest impact of this, at least in my mind is that the majority of patients when they’ve had a chronic cough for two months, they come into a clinic. So in that range of, say they’ve had a cough for one month to three months, depending on the individual, before they go in they think, “Oh I’ve just got a cold,” or “I’ve just got maybe some allergies.” But chronic cough for that long and you start to get like night sweats, maybe you’re losing weight too, these are other symptoms that you could have. Go into the clinic at that two to three-month window acid-fast stain can’t diagnose it. So they do, they try to do the diagnosis but it’s negative. They send them home.

Christina Sumners: Thinking they don’t have TB.

Jeff Cirillo: And that’s because the threshold is too high for the test, it’s not sensitive enough. So of those patients that are smear negative, culture positive, culture is more sensitive. It can detect down to about a hundred bacteria. We detect about 80-something percent. So across all samples, those that are culture negative, I mean culture positive, smear negative, smear positive, culture positive, we can detect 93 percent of those patients that would have been sent home at that two month window.

So that’s our negative predictive values, the scientific name for it. But yeah, so it’s very, very sensitive and we would send very few patients home that are still infected. So we look at it as a triage test, something that could be used upstream of every other test because of its high sensitivity. And then you’d say, okay, the false positive rate is about one in five. So of patients that come and are actually negative, we’d still pick up some false positives.

So that’s the biggest thing, they have to have follow-up. They don’t want to just do one test and send them home. Even today, they don’t do that. They usually follow up with multiple tests and there’s a couple like GeneXpert, which is a PCR-based test, or they do culture or other types of tests to confirm the diagnosis.

Because having a diagnosis of TB in the world is also a big negative social factor, right? People don’t want to be around them, they oftentimes can’t work. It’s a major problem, it affects the person’s life in all ways.

Tim Schnettler: And how important would the speed of getting that diagnosis back, cause you talked about how with the normal test it could take, you know, quite a while before you find out, days. With your thing, with what y’all are proposing and what y’all are working on, it’s a lot quicker. So how much would that affect everything?

Jeff Cirillo: In the view of myself and the World Health Organization, the primary issue is the patient comes in, oftentimes we lose track of them after they go away. And so this would allow us to do a diagnosis while the patient’s there and send them home with antibiotics, at a minimum, even if we haven’t done the follow-up test yet. And that can prevent transmission. Usually what you see is transmission to family members first. And so that’s a terrible situation cause they usually have kids at home and so you don’t want the children to be infected.

So that’s where we’re hoping to be able to prevent. And I didn’t mention it, but we say days, but that’s for acid-fast stain. For culture, the sensitive technique is six weeks or more.

Christina Sumners: Wow.

Jeff Cirillo: So it’s a huge change. The other advantage we have with this test that I think is very exciting is it does test whether or not the bacteria are alive.

So we can test the antibiotic on the bacteria while the patient’s there also. So if they do have bacteria, and we know that in 10 minutes, then we can add the antibiotic to the test, and in two hours with our test, we’ve shown with the antibiotics they use for treatment, we can determine whether or not the antibiotic will work.

Tim Schnettler: Wow.

Jeff Cirillo: So we can watch the bacteria die in the sputum cup.

Tim Schnettler: So you don’t have to give them an antibiotic that the bacteria are resistant to.

Jeff Cirillo: Exactly. And you’re wasting the antibiotics. You’re sending them home thinking, “Oh, I’m okay now.”

Tim Schnettler: They’re still sick, they can still transmit to other people. And yeah. Well, fascinating. That all sounds like really great innovation.

Jeff Cirillo: We’re excited about it. It’s just, there’s still a lot to be done to get it—

Tim Schnettler: Yeah.

Jeff Cirillo: —to patients and that’s really been my goal is to get it out.

I really have an ethical responsibility. It’s the first time I’d say—I mean we do a lot of interesting things, I like a lot of our work, of course, cause I wouldn’t be doing it otherwise—but this thing is scary for me and it could have an impact. But I’m having trouble getting each stage. Each stage is difficult.

You know, there’s a lot of compliance issues. We’re going through different commercial partners and you know, all along the way you have to deal with things. As a scientist you don’t expect patents, you know, and infringement on patents and you think, “Oh well protection of it is not that important.” But the problem is if somebody develops a test wrong in another country because they’re not following the procedures, that can completely destroy any credibility in that entire country.

So if it’s something that can impact people’s lives, then you’re talking, this is a life or death decision. And how we manage it, we have to manage it well so that it’s protected in each environment so we can make sure that it works the way it should work. Because I’ve had that problem already. We’ve had situations where we couldn’t get different people to get it done, and it usually turns out that they’re doing something a little differently than we were doing and it doesn’t work. So, we have to make sure that everything’s handled well. So we’re working on that. It’s going to take time though.

Christina Sumners: Yeah.

Jeff Cirillo: I think two years ago we thought we were about 18 months from getting it out to patients. And every time I keep pushing it back a little bit because there’s something that comes up, and it sounds like it’s simple stuff, but we have a liquid reagent system. We need to dry it. We need a powder that’s stable. Something that you send to China works just as well as if you send it to Russia, totally temperature different.

Tim Schnettler: You’re obviously very passionate about this. What got you started on this road? Was there something that just all the sudden piqued your interest?

Jeff Cirillo: So as a graduate student, one of the hardest decisions you make is what you’re going to work on for the rest of your life.

Christina Sumners: No pressure.

Jeff Cirillo: Yeah, it’s very, very tough. But I had pneumonia as a child and I’m a soccer player, so anything that affects my breathing. I couldn’t run, I couldn’t do much of anything. And so it totally knocked me out for, it must’ve been at least six months. I was having a hard time.

And so I was very keenly aware of respiratory issues, and then in graduate school I met a couple of different people. You know, there was a virologist I worked for a while that was really doing outstanding work, but I met Barry Bloom and he, at the time, was heavily involved in the World Health Organization and was very much involved in what was going on in India and some of the other countries where resources weren’t available.

And I started reading some of his stuff and he was working on respiratory-related—he works with TB a lot and his writing was just beautiful. He could communicate extremely well. And I read some of his papers and I went to him the next day. I said, “You know, I really would like to work for you. If anything, just teach me how to write.” And so he did. Actually, he crucified me for five years.

His writing, still to this day, I mean, I think I’m a better writer than I was when I was a graduate student, but I have never seen him take a document and not just rip every line to shreds. I wish I could write like that. And he does it very, very fast. So, very critical, very fast, very good writer. And I think that how he communicated problems in the developing world to large audiences, because I saw him go all over. We were in New York. I did my graduate work in New York. So he would go to the U.N. and he would talk to them, and many times I had the privilege of getting to hear him speak, and it’s just, it’s mind boggling how things are different than the U.S.

Christina Sumners: Right.

Jeff Cirillo: And so, the end result is, I actually, after I finished my PhD, I went to China for six months and worked at Beijing University, top biotechnology, and wanted to have kind of some firsthand experiences.

And I think that those, that combination of factors with my respiratory background and then kind of seeing it and realizing how big the problem was, that told me that I needed to try to do something about it if I could. So trying to do something before I die. Science, it’s a very slow process, so it takes a lot of time and a lot of dedication, so. But, I love it. It’s always been fun. I’ve always enjoyed it.

Christina Sumners: Well, it sounds like you’re certainly making progress along the way. So thank you so much for coming on the show and talking to us today.

Jeff Cirillo: Thank you. It’s been great.

Christina Sumners: And thank you all so much for listening, and we will see you next time.