MAC Lung Disease

MAC lung disease is a type of long-term (chronic) infection that affects your lungs. The Mycobacterium avium complex (MAC) group of microbes causes MAC lung disease. It can be difficult to treat if you don’t get a diagnosis quickly.

MAC bacteria are a type of nontuberculous mycobacteria (NTM) that naturally live in dust, soil and water. It’s the most common type of nontuberculous mycobacteria (NTM) infection. More than 86,000 people in the U.S. have some type of NTM infection, and MAC accounts for almost 8 out of 10 NTM infections. The rates have steadily grown over the last two decades. Healthcare providers expect the rates to keep increasing.

Most people who breathe in or swallow MAC bacteria don’t get sick. But some health conditions increase your chances of developing it. MAC lung disease is sometimes fatal.

Types of MAC infections

MAC infections include:

• Pulmonary MAC infections: These infections affect your lungs and respiratory system. It’s the most common type of infection.
• Disseminated MAC infections: These infections spread throughout your body through your bloodstream. They most commonly affect people with advanced AIDS and other types of conditions that affect their immune system (immunocompromised).
• MAC-associated lymphadenitis: This type mainly affects healthy children. It causes swollen lymph nodes, usually in your neck (cervical lymphadenopathy).

What are the types of MAC lung diseases?

There are two types of MAC lung disease:

• Nodular bronchiectasis
• Fibrocavitary disease

Nodular bronchiectasis

This is a milder form and more common. An infection develops in the small airways and air sacs in your lungs. It causes pulmonary nodules that are visible in imaging tests, like CT scans. Tiny nodules aren’t always visible in chest X-rays. The nodules grow slowly. Long-lasting inflammation causes your airways to permanently widen (dilate). Healthcare providers call this bronchiectasis. This makes it harder for your body to clear infections. It also increases your risk of new infections.

This type is more common in females who’ve completed menopause and don’t smoke.

Fibrocavitary disease

This is the more severe form of MAC lung disease. It’s less common and harder to treat. It’s a deeper infection that causes a hole in your lung tissue. You need treatment as soon as possible if you have fibrocavitary disease.

You’re more likely to have fibrocavity disease if you smoke or have emphysema.

Symptoms of MAC lung disease

MAC lung disease symptoms may include:

• Long-term (chronic) cough, which may or may not include coughing up phlegm
• Feeling very tired (fatigue)
• Coughing up blood
• Low-grade fever between 99.6 degrees Fahrenheit (37.5 degrees Celsius) and 100.3 F (37.9 C)
• Night sweats
• Reduced appetite and unexplained weight loss
• Shortness of breath (dyspnea)
• Chest pain

MAC lung disease symptoms vary. You may not have the same symptoms as someone else who has the condition. The symptoms are also often nonspecific. That means if you do have symptoms, they’re broad — they may be symptoms of a wide range of conditions.

MAC lung causes

MAC bacteria naturally live in soil. Stirring up soil or dust, like through gardening or playing outside, can send bacteria into the air, where you may breathe them in.

MAC also naturally live in water. This includes the water in your home, even showerheads and hot tubs.

It’s important to remember that for most people, the bacteria are harmless. We encounter nontuberculous mycobacteria every day, and most people never develop an infection.

But in a small number of people who have certain risk factors, the bacteria settle in their lungs. It then grows slowly, often over many years. The resulting MAC lung infection causes minor inflammation and permanent changes to your airways. The changes may continue until a healthcare provider can diagnose it and provide treatment.

What are the risk factors?

MAC lung disease can affect anyone. But certain people face a higher risk. You’re at a greater risk if you’re over 65 and have gone through menopause.

You’re also more likely to get MAC lung disease if you smoke, have a weakened immune system or a lung condition such as:

• Bronchiectasis
• Chronic obstructive pulmonary disease (COPD)
• Cystic fibrosis
• Emphysema

A history of tuberculosis (TB) also increases your odds of getting MAC lung disease.

Is it contagious?

No, you can’t catch a MAC infection from someone else. But sometimes, MAC lung disease affects more than one biological family member. Experts believe certain people have a genetic variation that makes them more likely to get a MAC infection.

How doctors diagnose MAC lung disease

A healthcare provider will review your medical history, ask about your symptoms and perform a physical exam. If they suspect MAC lung disease, they’ll recommend tests. These tests may include:

• Sputum cultures (lung excretions): A healthcare provider examines a sample of thick mucus from your lungs (sputum).
• Imaging tests: Chest X-rays and CT scans allow providers to see changes in your lungs.
• Bronchoscopy: A provider inserts a thin camera through your nose or mouth and down your windpipe (trachea) to look at your lungs. A provider typically only recommends a bronchoscopy if other tests don’t allow them to make a diagnosis.

MAC lung disease can be challenging to diagnose. A provider may refer you to an infectious disease doctor or a lung specialist (pulmonologist).

Is MAC lung disease curable?

MAC lung disease can be challenging to treat. But healthcare providers can cure it. Your odds are better if you have nodular bronchiectasis and get an early diagnosis.

How do you treat it?

MAC lung disease treatment depends on how bad your symptoms are. Healthcare providers may recommend:

• Watchful waiting: You may not need immediate antibiotic treatment if you have minor symptoms and imaging tests don’t show many changes. But providers will closely watch your condition with regular tests and check-ups.
• Airway clearance (chest physiotherapy): This is a group of therapies that helps your lungs clear sputum from your airways. It includes different breathing treatments through a nebulizer. It may also involve medical devices, like vibrating vests, that help move sputum out of your lower airways. Providers most often recommend airway clearance if you have bronchiectasis.
• Medications: If airway clearance alone isn’t enough, providers may prescribe long-term antibiotics. You’ll take three or more antibiotics for at least 12 months from the time your sputum cultures no longer grow mycobacteria. The different antibiotics help reduce your chances of developing antibiotic resistance.
• Surgery: In rare cases, a surgeon may need to remove a part of your infected lung (lung resection). After surgery, you’ll take a course of antibiotics to kill any lingering bacteria.

What are the side effects of treatment?

Taking antibiotics to treat MAC lung disease can cause side effects. Some common effects include:

• Abdominal pain
• Diarrhea
• Loss of appetite
• Nausea and vomiting
• Reddish orange pee, poop, spit (saliva), sweat and tears

It’s important to take your full course of antibiotics to treat MAC lung disease. But it can be difficult to take them for such a long time, especially if you develop symptoms. Talk to a healthcare provider if antibiotic side effects bother you. They can recommend ways to help manage them.

When should I see my healthcare provider?

Reach out to your healthcare provider if you’re sick or have new or worsening symptoms after a MAC lung disease diagnosis.

You may wish to ask them the following questions:

• What caused MAC lung disease?
• What type of MAC lung disease do I have?
• Do you recommend treatment?
• What treatment options do you recommend?
• Is surgery right for me?
• What are the risks of surgery?
• Are there steps I can take at home to help improve my breathing?
• How can I prevent future MAC lung infections?

What can I expect if I have MAC lung disease?

MAC lung disease can be tough to treat. Most people need to take several antibiotics for at least a year. While you’re taking antibiotics, you’ll have regular check-ups with your healthcare provider. They’ll make sure the medicine is working and adjust your dosage or medication if needed.

Providers consider the infection gone if your sputum cultures stay clear for 12 months. But MAC can come back. This may happen after another exposure. It can also happen if some mycobacteria are still hiding in your lungs. You’re at a higher risk if you have other health problems that make it easier for you to get sick.

If MAC causes lung damage, it usually doesn’t heal. So, after treatment, you may still have breathing problems. Before you start treatment, your provider will talk to you about what to expect and what the goals are for your care.

Is it terminal?

In some people, MAC lung disease can cause respiratory failure and death. But getting a diagnosis and starting treatment as soon as possible helps reduce the long-term risks.

How long can I live with MAC lung disease?

It depends on many factors. These include the severity of your case of MAC lung disease, any other conditions you may have (comorbidities) and your overall health. A healthcare provider will give you a better idea of what to expect.

Is there anything I can do to feel better?

You can help ease MAC lung disease symptoms by:

• Clearing mucus out of your airways (Respiratory therapists can teach you breathing techniques, controlled coughing and how to position yourself so mucus drains from your lungs.)
• Getting regular physical activity
• Getting vaccinated to lower your risk of other respiratory illnesses, like the flu and pneumonia
• Maintaining a healthy weight for you
• Quitting smoking and avoiding secondhand smoke and other lung irritants

Can MAC lung diseases be prevented?

MAC bacteria are common, and most people who encounter MAC bacteria won’t get sick. But you can help lower your risk of exposure by:

• Adding water to potting soil before working with it to reduce dust
• Avoiding hot tubs and saunas that recirculate hot, steamy water
• Running exhaust fans in your bathroom and kitchen to clear out steam
• Setting your home’s water heater to at least 130 F (54.4 C)
• Wearing a mask while working in your garden or yard