Surveys suggest that clinicians diverge from guidelines when treating Mycobacterium avium complex (MAC) pulmonary disease (PD). To determine prescribing patterns, we conducted a cohort study of adults >66 years of age in Ontario, Canada, with MAC or Mycobacterium xenopi PD during 2001-2013. Using linked laboratory and health administrative databases, we studied the first treatment episode (>60 continuous days of >1 of a macrolide, ethambutol, rifamycin, fluoroquinolone, linezolid, inhaled amikacin, or, for M. xenopi, isoniazid). Treatment was prescribed for 24% MAC and 15% of M. xenopi PD patients. Most commonly prescribed was the recommended combination of macrolide, ethambutol, and rifamycin, for 47% of MAC and 36% of M. xenopi PD patients. Among MAC PD patients, 20% received macrolide monotherapy and 33% received regimens associated with emergent macrolide resistance. Although the most commonly prescribed regimen was guidelines-recommended, many regimens prescribed for MAC PD were associated with emergent macrolide resistance.
Keywords: Canada; Mycobacterium avium complex; Mycobacterium infections; Mycobacterium xenopi; Nontuberculous mycobacteria; Ontario; nontuberculous; respiratory infections; treatment; tuberculosis and other mycobacteria.