Pulmonary nocardiosis following nodular bronchiectatic Mycobacterium avium complex pulmonary disease in an immunocompetent patient.

A woman in her 70s with a history of nodular bronchiectatic Mycobacterium avium complex pulmonary disease (MAC-PD) presented with an exacerbated productive cough and worsening findings on chest imaging. Although repeated sputum culture tests were negative for acid-fast bacilli and only revealed normal respiratory flora, a bronchoscopy identified Nocardia sp. Consequently, she was diagnosed with pulmonary nocardiosis and was successfully treated with levofloxacin. It is known that pulmonary nocardiosis can manifest in immunocompetent individuals with bronchiectasis. For cases of refractory nodular bronchiectatic MAC-PD, it is vital to consider bronchoscopy to identify potential co-infections, such as Nocardia.