Medical mystery: Why did her chronic cough linger for a decade?

A woman in her 60s came to my office last year in search of a new pulmonologist, as her longtime lung specialist had recently retired.

She had a 10-year history of chronic cough and fatigue. When we talked about her medical history, she recounted multiple lung diagnoses over the last decade.

Her first diagnosis came from her primary care physician who thought her daily cough suggested bronchitis, an infection that causes inflammation in the lining of your bronchial tubes. Her doctor prescribed antibiotics commonly referred to as Z-Pak, a five-day oral course of azithromycin used to treat bacterial infections. Her daily cough went away for a little while but eventually returned.

In 2016 she was diagnosed with breast cancer and a chest X-ray showed signs of a possible lung infection. Concerned it could be tuberculosis (TB), doctors referred her to a pulmonologist for follow up. If left untreated, TB, a contagious airborne bacterial infection, can be fatal.

The pulmonologist ordered a blood test, which ruled out TB, and a subsequent lung biopsy, which showed nothing unusual. Based on follow-up CAT scans and a physical exam, the pulmonologist diagnosed her with bronchiectasis, a chronic condition where the airway walls (the bronchi) become irreversibly thickened from inflammation and infection. Because of this damage, the airways lose the ability to properly clear out mucus, often leading to a daily cough that can persist over several months or even years. Her doctor prescribed a steroid for a few months to reduce the inflammation in her airway.

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Occasionally, her symptoms flared up. These episodes, known as exacerbations, are common among bronchiectasis patients and often caused by infection. When that happened, her pulmonologist would prescribe antibiotics to treat the infection. Her cough would lessen but she reported they never completely abated.

When I examined her, I heard lots of “crackling” in her lungs. What most concerned me about her medical history was that her cough persisted for so many years and never fully responded to medications. I wondered if her bronchiectasis was the sole diagnosis or the result of another lung disease.

I suggested an additional test that had not yet been performed, which would ultimately reveal a new diagnosis.

I ordered a sputum test in hopes of identifying any bacteria that might have infected her lungs. I asked her to cough deeply and spit any phlegm that came up from her lungs into a container. The sample was then sent to the lab for processing.

Results from the test confirmed the presence of mycobacterium avium complex (MAC) and revealed a previously missed diagnosis: MAC lung disease.

MAC lung disease is an infection caused by a group of bacteria that are naturally found in soil or water. Most people who inhale these bacteria, usually through dust or water particles, don’t get sick. But people who are older, have chronic lung conditions, or are immunocompromised are more at risk of developing a slow-growing infection. Research has shown that postmenopausal women are also at greater risk. Left untreated, MAC can cause permanent lung damage.

It’s important to note that MAC are a type of nontuberculous (TB) mycobacteria, meaning the lung disease is not contagious.

Chronic cough is the most common symptom of MAC. Some people experience fatigue, shortness of breath, and unplanned weight loss. When any of these symptoms persist over time or don’t respond to treatment, that’s a sign to test for MAC.

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Because MAC symptoms are subtle and mimic other chronic lung conditions, many MAC patients will experience symptoms for months or even years before getting the correct diagnosis.

Lung imaging can show potential signs of MAC infection, but a sputum test to confirm the presence of bacteria is the only way to definitively diagnose this disease.

This slow-growing infection can be challenging to get rid of so it’s important to find a pulmonologist with experience treating MAC lung disease.

The standard of care is a combination of three oral antibiotics taken over months or sometimes up to a year to clear the infection. Unfortunately, prolonged antibiotic use can have serious side effects including loss of vision or hearing. I sent my patient to ophthalmology and audiology for baseline tests so we could monitor her during treatment.

She also elected to join a randomized clinical trial I am involved in that is studying if MAC treatment could be as effective with only two antibiotics. The hope is that this would lower patients’ risk of debilitating side effects.

She started antibiotics in September 2021 and experienced minimal side effects. By December, her chronic cough was 80% improved.

By January, repeat sputum tests showed her MAC infection had cleared. Unfortunately, in some patients the infection can recur, which is why she’ll continue treatment through the end of the year.

Daniel A. Salerno is the director of critical care services at Temple University Hospital and an associate professor of thoracic medicine and surgery at the Lewis Katz School of Medicine at Temple University.