Nontuberculous mycobacterial lung disease can be challenging to treat


Living in coastal areas of Florida and California has great appeal for many, with the warm, sunny climate and nearby fresh water and salt water.

But, unknown to many, those balmy coasts also carry the risk of infection from nontuberculous (atypical) mycobacteria (NTM). Unlike its relative, tuberculosis, NTM is not transmitted from person to person, with one exception: patients with cystic fibrosis.

It is estimated that there were 181,000 people with NTM lung disease in the U.S. in 2015, and according to one study, the incidence is increasing by 8.2% annually among those aged 65 years and older. But NTM doesn’t only affect the elderly; it’s estimated that 31% of all NTM patients are younger than 65 years.

With the warm, moist soil and water, NTM is most commonly found in Florida, California, Hawaii, and the Gulf Coast states. The incidence is somewhat lower in states along the Great Lakes. Other states are not without risk – but NTM is perhaps even more likely to be overlooked in these states by physicians because of a lack of awareness of the disease.

Rebecca Prevots, PhD, MPH, chief of the epidemiology and population studies unit of the Division of Intramural Research at the National Institute of Allergy and Infectious Diseases, told this news organization that “why NTM is increasing is one of the most common questions” she gets, followed by whether it is due to climate change. “The short answer is, we don’t know.”

She suggests that the increase in diagnoses is due to a combination of increased awareness, host susceptibility, and perhaps environmental changes. One problem is that NTM is not a reportable disease. Also, public health resources have been decimated, both through funding cuts and loss of personnel. Dr. Prevots said, “It’s not just NTM surveillance that is important, but you can’t just make a certain condition reportable and expect to have good data without putting resources to it. ... Diseases are made reportable at the state level. There’s no mandated reporting up to CDC. So CDC is piloting reporting events through their emerging infectious program.”

Anthony Cannella, MD, assistant professor of infectious diseases at the University of South Florida (USF), is in the midst of NTM. He told this news organization that “there’s a huge circle with big old dots right over the center of the state.” He is adamant that “a soil-water survey has to occur. We need to know what the devil is happening.”

Florida legislators agreed to allocate $519,000 for NTM testing and surveillance in 2019. But Florida Governor Ron DeSantis vetoed that line item in the budget. WUSF (a National Public Radio affiliate on the USF campus) was unable to get a response to their query about this from the governor’s office.

Who gets NTM?

Mycobacterium avium complex primarily causes lung disease, which presents as two clinical syndromes.

“These infections don’t affect everyone,” Kenneth Olivier, MD, MPH, chief of pulmonary clinical medicine, Cardiovascular Pulmonary Branch of the National Heart, Lung, and Blood Institute, said in an interview. They affect “patients that have underlying genetic conditions that cause abnormalities in the airway clearance mechanisms, particularly cystic fibrosis and primary ciliary dyskinesia [and], to some extent, patients with COPD.”

The second group is “comprised mainly of postmenopausal women, many of whom have had no predisposing medical problems prior to onset of generally frequent throat clearing or chronic cough, which is what brings them to medical attention.” Dr. Olivier added that “many of these patients have a fairly unique appearance. They tend to have a high prevalence of curvature of the spine, scoliosis, indentation of the chest wall (pectus excavatum), and physical characteristics that overlap heritable connective tissue disorders like Marfan syndrome or Ehlers-Danlos syndrome.”

Dr. Olivier pointed out a major problem in NTM diagnosis and treatment: “The guidelines-based approach to chronic cough generally calls for treating postnasal drip, airway reactivity, asthma type symptoms first empirically, before doing different diagnostic studies. That generally causes a delay in obtaining things like CT scan, where you can see the characteristic changes.”

Dr. Cannella added, “People are starting to become more aware of it. It’s kind of like pneumocystis back in the 80s. ... We’ve had patients who have had long periods of febrile neutropenia, and NTM wasn’t on the radar. Now we’ve picked up at least seven or eight.”

In addition to pulmonary infections, nosocomial outbreaks have occurred, owing to contaminated heater-cooler units, catheter infections, nail salons, or to medical tourism. These more commonly involve rapidly growing species, such as M abscessus, M chelonae, and M fortuitum. Clinicians should also be aware of skin infections from M marinum, which come from wounds from aquariums, fish, or shellfish. Incubation can occur over months, highlighting the importance of a detailed history and special cultures.


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