What If I Am Resistant to Antibiotics for MAC?

Reviewed by: HU Medical Review Board | Last reviewed: December 2022 | Last updated: January 2023

As many as 80 percent of typical MAC lung disease cases can be cured with treatment. However, in some cases, MAC germs develop a resistance to antibiotic drugs. When this happens, MAC lung disease can become harder to treat.1,2

What is antibiotic resistance?

Antibiotics are drugs that attack the germs that cause MAC lung disease, or Mycobacterium avium complex (MAC) germs. Most cases of MAC can be treated with antibiotics.1

But sometimes, over time, germs try to protect themselves against the effects of drugs. They can change (mutate) to avoid being targeted and attacked. Germs can also destroy or stop drugs before they have a chance to work. These changes get passed onto other germs, and eventually they can lead to a resistant infection.3,4

When MAC germs change to the point where antibiotics no longer destroy them, this is called antibiotic resistance.1,3,4

How does resistance develop in MAC lung disease?

Several different factors can cause MAC germs to start changing and develop resistance.

Undertreatment

A main cause of antibiotic resistance is taking the drug less often than prescribed or not finishing all of it. This is called undertreatment, and it can allow some bacteria to avoid being destroyed and start changing.1,3,4

An example of this would be taking a drug once a week when it was meant to be taken every day. Following your treatment plan exactly and not making changes on your own is important to avoid antibiotic resistance.1,3,4

Treatment with macrolides

One of the most common types of drug resistance in MAC treatment happens with type of drug called a macrolide. Many MAC lung disease treatment plans include 3 drugs: a macrolide and 2 others. The additional 2 antibiotics are given to reduce the risk of resistance. Macrolide resistant (MR) MAC germs can grow when a person with MAC takes only the macrolide drug instead of the full combination of drugs.1,2

However, other lung conditions, such as bronchiectasis, are sometimes treated with macrolides only. Bronchiectasis and MAC lung disease share many features. It is possible for a MAC diagnosis to be missed or delayed due to this overlap.1,2,5

In these cases, a person with MAC may take only one drug to treat their bronchiectasis. This can increase the risk of resistance before MAC treatment even starts. Fortunately, most cases of MAC are diagnosed before the germs have started to change.1,2,5

What are the effects of antibiotic resistance?

While most cases of MAC lung disease are treatable, resistant cases can be more challenging to treat. MAC infections that have come back again after treatment (relapsed) are more likely to be resistant, too.1,6

The cure rate for people who have tried multiple antibiotics and have had surgery may be as low as 20 percent. Some estimates suggest that the death rate (from any cause, including MAC) is higher for those with resistant MAC, too. Nearly half of people with resistant MAC may die within 5 years.1,5,6

When MAC germs become resistant, more aggressive treatment is needed to treat the infection. You may need to take more prescribed drugs or take them more often. For example, if you were taking drugs 3 times a week, you may need to start taking them daily.1

Adding more drugs or taking them more often can lead to additional side effects. Talk to your doctor about the risk of side effects with more aggressive treatment.1

What other treatment options are available?

Although it might be scary to hear that you have resistant MAC lung disease, there are still options for treatment. Some people may qualify for a lung resection. This is a surgery that removes the infected part of the lung. The surgery can reduce the amount of infected lung tissue and overall burden of MAC germs.1,6,7

But surgery carries some risks. As tissue is removed, new channels between areas of the body that are not usually connected can form. These are called fistulas. Depending on where a fistula is, different complications can arise. Surgery also increases the risk of other infections, too.1,6,7

In addition, certain drugs can be added to your treatment plan before surgery is needed. They can also be taken after surgery to destroy any MAC germs that remain. These drugs include clofazimine, amikacin, and bedaquiline. Several newer drugs can be taken in different ways, such as inhaled versus put into a vein. More research is needed to determine how effective these drugs may be over time.1,2,6-8

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