Dear Doctors: I suffered extensive fatigue that I had attributed to a COVID-19 infection. Then a lung culture found something called mycobacterium avium complex. Would you kindly consider discussing this? I realize it’s not a common illness, but for that reason it can go undetected and undiagnosed.
Dear Reader: Mycobacterium avium complex refers to a group of bacteria that are naturally present in the soil, water and dust all around us. Also known as MAC, these microbes are harmless to the majority of people. But when someone is living with a chronic lung disease or a weakened immune system, inhaling the bacteria can lead to an infection. When this occurs, it is known as MAC lung disease. Unlike tuberculosis, which is also a bacterial lung infection, MAC lung disease is not contagious.
MAC lung disease can affect the lungs in two different ways. One, known as nodular bronchiectatic, causes tiny knots to develop within the smaller airways and air sacs of the lungs. Over time, the resulting inflammation leads to scarring in the tissues of the lungs. This makes it difficult to naturally clear mucus, which, in turn, increases the risk of developing a respiratory infection. The other, more aggressive form of MAC is known as fibrocavitary disease. This is when damage to the lung tissue leads to the development of pits, or even holes, in the lung tissue.
Symptoms of both forms of MAC lung disease include the pervasive fatigue that you experienced. This is due to the extra work your body is doing to try to fight off the infection, and to the damage to the lung tissue itself. Additional symptoms can include a chronic cough that can be dry or may produce mucus; shortness of breath; a sensation of heaviness or pain in the chest or lungs; a low-grade fever that is not associated with another illness; unintentional weight loss; a decrease in appetite; and night sweats. If coughing brings up mucus or sputum, it is possible that it may be tinged with blood.
Diagnosis begins with a physical exam, a medical history and a detailed description of symptoms. When MAC lung disease is suspected, sputum cultures can identify the presence of bacteria. These bacteria are common, so repeated cultures may be required to confirm a persistent infection. Scans, such as a CT or an X-ray, can reveal physical changes to the lungs. A bronchoscopy, which uses a flexible scope to examine the lungs, can confirm a diagnosis.
Treatment depends on each person’s specific symptoms, current physical health and medical history. When symptoms are mild, the condition may be closely monitored but not actively treated. This is known as watchful waiting. Some people are prescribed therapies to help clear mucus -- and bacteria -- from the lungs. When needed, antibiotics are prescribed. This therapy often lasts for a year or more. And due to the challenges of antibiotic resistance, it typically requires the use of multiple antibiotics.
To ease symptoms, your doctor has likely urged to you to eat a healthful diet, avoid tobacco, do breathing exercises and get vaccinated for flu and COVID-19. We hope you follow through.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
