Nontuberculous mycobacteria infections in patients receiving immunosuppressive agents

Bacterial infection is a common cause of bronchiectasis and persistent microbial colonisation is thought to be a central component of the ongoing pathophysiology of the disease. Many bronchiectasis patients also have underlying immune-mediated inflammatory diseases that require treatment with immunosuppressive medications. Examples of these medications include nonbiologic disease-modifying antirheumatic drugs, such as methotrexate or leflunomide, and biologic disease-modifying antirheumatic drugs, such as etanercept or infliximab. These medications are known to place all patients at greater risk of infection, and theoretically can contribute to persistent bacterial colonisation and recurrent pulmonary infections in bronchiectasis patients. Ultimately, this can lead to bronchiectasis progression. With the increasing use of these medications, the safety of their use in patients with bronchiectasis remains a question. In this chapter, we discuss the infection risk of immunosuppressive medications in patients with bronchiectasis, the management of these infections (paying special focus to pulmonary NTM infections) and how to balance the need for continued immunosuppression with further infection risk.