Non-Tuberculous Mycobacterial Lung Disease

Additional Info

• Audio File:uab/ua102.mp3
• Doctors:Solomon, George
• Featured Speaker:George Solomon, MD
• CME Series:Clinical Skill
• Post Test URL:https://cmecourses.som.uab.edu/mod/quiz/view.php?id=3031
• Guest Bio:George Martin Solomon, MD specializes in Pulmonary, Allergy & Critical Care Medicine at UAB Medicine.
  
  Learn more about George Martin Solomon, MD 
  
  Release Date: April 12, 2019
  
  Expiration Date: April 12, 2022
  
  Disclosure Information:
  
  Dr. Solomon has the following financial relationships with commercial interests:
  
  • Grants/Research Support/Grants Pending - Vertex, Translate Bio, Bayer, Insmed, CFF, NIH, Electromed
  
  • Consulting Fee - Electromed
  
  • Board Membership - Gilead, Vertex
  
  • Payment for Lectures, Including Service on Speakers Bureaus - Insmed
  
  Dr. Solomon does not intend to discuss the off-label use of a product. No other speakers, planners or content reviewers have any relevant financial relationships to disclose.
  
  There is no commercial support for this activity.
• Transcription:Melanie Cole, MS (Host): UAB Medcast is an ongoing medical education podcast. The UAB Division on continuing education designates that each episode of this enduring material is worth a maximum of .25 AMA PRA Category 1 credit. To collect credit, please visit uabmedicine.org/medcast and complete the episode’s post-test.
  
  Nontuberculous mycobacterium lung disease is particularly vexing for clinicians to diagnose and treat. My guest today is Dr. George Solomon. He’s an assistant professor in the division of pulmonary allergy and critical care medicine at UAB Medicine. Dr. Solomon, what is the prevalence of nontuberculous mycobacterium lung disease, and what do we know about this disease?
  
  George Solomon, MD (Guest): Yeah, that’s a great question. We don’t know exactly what the prevalence of that illness is. I can tell you that the prevalence and incidence of new cases is certainly on the rise. A lot of that has to do with detection of the illness, awareness of the illness, an increasing aging of our population, but we don’t have a good estimate of prevalence and incidence. It’s not a common disease so it’s not a one in a thousand of the population have this illness, but it’s certainly not so uncommon that it’s considered a significantly rare illness anymore either. I believe that’s because of the shifting demographics of our population. We’re seeing more patients exposed and becoming symptomatic with the illness. So therefore, those numbers are influxed.
  
  Host: One thing I found interesting, Dr. Solomon, is that NTM infection, unlike tuberculosis, don’t require public health reporting. Do you feel this hinders an accurate understanding of the epidemiology or may not be reflective of changes in prevalence?
  
  Dr. Solomon: It’s a great question. The real reason why the infections are not reported as a public health concern the same as other communicable infections, like tuberculous, is really the communicability of the infection. In other words, the rate at which it’s passed from patient to patient. The understanding of the biology of the illness is such that most of the acquisition of the infection is from susceptible people getting it from the environment. Therefore, for it to be a public health reported illness doesn’t make as much sense.
  
  That said, because we don’t catch the data in a standardized fashion, the estimates of incidence prevalence are going to be highly varied as we just discussed. So, part of me says that it’s the right thing to do because there are definitions of what has to be a reportable illness ‘cause of communicability. The other side to me says that if we were to make it a public health reported illness, we may have a better estimate of incidence and prevalence to understand how common it is.
  
  Now soil samples are gathered for the amount of the organism being captured in the soil throughout the state. So, we have an idea of states that high levels of this being in the water supply and in the soil, which is the two common reservoirs for the infection for patients to inquire them. So, we have an idea about that, but as far as the number of new cases, we are going to be limited unless we make it a reportable illness.
  
  Host: Dr. Solomon, you just mentioned soil and water. Where else might the bacteria be found and what are the mechanism of infection? How does NTM infection the body and what are some commonly encountered of NTM pulmonary infections?
  
  Dr. Solomon: Great question. So, let me take the first part of your question first. So, the natural reservoirs that I stated for this infection are basically the environment. Our soil and water and especially the deep south. And, believe it or not, areas like archipelago islands, like Hawaii, have high amounts of these organisms in the soil and water samples. The bugs are a little bit smart in that they can lie in a dormant state, much like fungus can. So, they can live in a dormant state in these environments for a long time, requiring very little nutrients and only become sort of active and replicating when they hit their host, which is in this case humans.
  
  The most common infection that we encounter, most common nontuberculous mycobacterium infection we encounter is called mycobacterium avium. It exists in a complex of several species, which are highly interrelated. Those organisms tend to present with an infection that tends to be an indolent infection. That tends to cause cough, malaise, and low-level fevers or night sweats in the host, the human host. So, the most common presentation of this illness tends to be an indolent illness with some fevers, cough, and the onset, eventually, of increasing pulmonary symptoms like cough and breathlessness as the most common presenting symptoms of this condition. But, because of the slow nature of these infections and their infectivity, we oftentimes see that patients have had symptoms that are suggestive of this for quite some time before they either present for diagnosis or are effectively diagnosed with a condition.
  
  Host: Well then, Dr. Solomon, what are the diagnostic criteria because there are some related disorders were comparisons may be useful for a differential diagnosis, but what would even have a provider think along these lines?
  
  Dr. Solomon: Yep. So, the common circumstances in which this condition is considered tends to be the right demographics or the right host susceptibility. So, let me try to explain what I mean by those two things. These infections tend to present most commonly in elderly patients. So that means patients that are in their sixth or later decades of life. Most commonly, patients infected are in the age range of 65 plus. So, these are patients that are, at present, considered in the senior citizen age bracket. So that age bracket with the symptoms I've outlined is the circumstance in which you should most effectively think this patient may have an NTM type infection.
  
  Now there are other circumstances in which we encounter this very frequently too. Patients that have known structural lung disease. Those include chronic obstructive pulmonary disease, or COPD; known or established bronchiectasis due to any of a number of conditions, cystic fibrosis, primary ciliary dyskinesia. Any of a number of those including immunodeficiency disorders. Those patients are also exquisitely susceptible to picking this up earlier in life. So, if the condition is encountered, if those types of symptoms are encountered in a patient with a known bronchiectasis lung type disease or structural lung disease, it should be considered anywhere early anywhere in their presentation of illness.
  
  If the de novo case, in other words the patient is having these types of symptoms, it’s more common to encounter and more likely to be diagnosed in patients who are older, in their sixth or later decades of life. So those are the two patient populations to which you should think about this condition. Not to say it can't happen sporadically in other age brackets in which there aren’t preexisting conditions that make the patient susceptible, but it’s most commonly encountered in those two patient buckets of groupings of patients.
  
  Host: Then let’s talk about the standard therapies. Since it’s aerosolized and aerobic, what are the standard therapies you would use and what are some of the challenges when deciding on these therapies? Doctor since it can be in water heater or a shower or a spray bottle or even a hot tub, there’s all kinds of places. Is there then a process for checking the area where you suspect it might be present?
  
  Dr. Solomon: That’s a great question. So, let me take the question of standard therapy first, and then I’ll answer your question about how to deal with preventative measures for the condition. So standard therapy for this condition depends upon the particular organism in this bucket of infections we call nontuberculous mycobacterium, or NTM infections, we encounter. We typically encounter most commonly—this would account for the overwhelming majority of cases. Probably 80 to 90% of cases, we encounter two different species.
  
  One is the MAC complex, the mycobacterium avium complex we call MAI infection, most commonly. That accounts in the U.S for about two-thirds or greater or the cases that we encounter. That infection, assuming there aren’t complications arising from the infection like cavitary lung disease or extra pulmonary lung disease-- which we don’t have time to get to in the interview disease-- assuming it’s mild lung disease can be relatively well treated with a prolonged course of three oral antibiotics. Those usually involve, as a standard this is set by the American Thoracic Society in correlation with the IDSA, the Infectious Disease Society of America. Usually those two governing bodies recommend three oral antibiotics, which include a macrolide antibiotic, either clarithromycin or azithromycin, as well as the addition of two other antibiotics which were developed for treating tuberculosis including ethambutol and rifampin or one of its derivatives. Those antibiotics, in general, are effective at treating patients if taken effectively until you reach microbiologic cure, which means successive clear cultures of the organism and improvement of symptoms and radiology. Then the patient continues those on for 12 plus months after clearance. So, if that’s the case, that’s fairly easily treated infection.
  
  Now there are other organisms, the second most commonly encountered organism is one called mycobacterium obsessive complex. It also has several interrelated species which are treated. These require a bit more aggressive therapy. They tend to be more invasive organisms. So, they require an initial period of oral plus intravenous antibiotics followed by a prolong period of oral plus inhalation antibiotics. So just to clarify, intravenous plus oral antibiotics for an initial period followed by inhalational plus oral antibiotics for a prolonged period. Depending on the type of organisms that’s encountered in that complex is exactly which of those are encountered are used and for how long. So that’s a good bit more complicated infection treatment regimen, but it also can be effective, and it’s been shown to be relatively effective and some longitudinal studies which have been conducted. So that sort of answers the outlay of how we treat it. It’s dependent upon what organism and then prolonged treatment to ensure sustained clearance of cultures and symptoms and radiographic appearance.
  
  Now your other question related to is there a way to prevent this infection from either incurring to start with or from recurring once you’ve inquired it. There has been some literature looking at whether or not you should not use hot showers, for instance, because showers are known to aerosolize these infections to people with susceptible lungs. Studies have shown that in fact not using the shower does not prevent the patient from having encounters with this.
  
  There are a couple things that I recommend to patients which are based loosely on the literature which I think are good ideas for patients. This first thing is, if possible, minimize significant soil exposure like significant farming, digging, gardening if it can be removed from the patient’s life without effecting their quality of life. The second is the circumstances in which we encounter a lot of these organisms being encountered in a more epidemic type of level is in patients that visit steam showers or saunas or enclosed hot tubs. So those are the circumstances in which you have a reservoir of water, which is not always changed out and cleaned effectively, and it’s very hot and it’s being aerosolized in a very aggressive fashion to create the circumstance that’s pleasing for people at a spa or resort or whatnot. So, I do tell patients that are susceptible of this or have had this infection before if at all possible, to avoid that circumstance in addition to the gardening or farming soil exposures. Those are not rooted in strong evidence for effectiveness of minimizing recurrence of infection. Really the key to recurrence of infection is to have effective microbiologic cure as outlined earlier and sustaining that with clearance.
  
  The other thing that can help with patients, this has been shown in some studies, is clearing the airways of effected material. So, in addition to treating the infection with antibiotics, mechanical and medical therapies which clear infected mucous throughout the course of treatment and then beyond the course of treatment afterwards so that if infection were to try to reestablish itself, it’s removed quickly by enhanced mucous clearance therapies. Those have been shown to help reduce the re-infectivity rate. So that’s recommended by most practitioners that treat patients with this illness.
  
  Host: What an interesting topic we’re discussing here today. Dr. Solomon, in summary, tell other physicians what’d like them to know about recognizing NTM lung disease and when you feel it’s very important to refer.
  
  Dr. Solomon: Yeah. So, these are my kind of hallmarks for this. If you have a patient in which you expect mycobacterial disease, nontuberculous mycobacterial disease, it’s not one of those things that you're going to just stumble upon the answer that they have it or not. You're going to have to go searching. So, if they have susceptibilities we've outlined earlier or they're having a constellation of symptoms in a patient that you wouldn’t otherwise think is susceptible, you're going to have to get imaging and you're going to have to try to get sputum samples to try to look for this organism.
  
  Now in certain circumstances throughout our state and throughout our country, all of that diagnostic evaluation is challenging to be able to be done in a local office. So, if it can't be done, make the referral even if you don’t know the patient has the illness. Even if you're just suspecting it based on a chest x-ray or a constellation of symptoms and we can assist with the diagnosis and then immediately moving a patient into treatment as we go along. So, I recommend early and often thinking about referral because this can be a very challenging illness to make the diagnosis for. Then the management of treatment for this is not trivial. It requires prolonged antibiotics which have a lot of side effects and require a lot of patient coaching and some knowledge about how to do that. So, I recommend early referral if you're considering this and don’t have a significant amount of experience dealing with the antibiotics or advanced diagnostics.
  
  Host: Thank you so much, Dr. Solomon, for coming on with us today and discussing this really interesting topic that not everybody knows about and where it’s acquired and when it’s important to refer. A community physician can refer a patient to UAB Medicine by calling the MIST line at 1-800-UAB-MIST. That’s 1-800-822-6478. You're listening to UAB Medcast. For more information on resources available at UAB Medicine, you can go to uabmedicine.org/physician. That’s uabmedicine.org/physician. This is Melanie Cole. Thanks for tuning in.
  
  
  
• Hosts:Melanie Cole, MS