Abstract
MAC and M. abscessus lung diseases occur predominantly in females with bronchiectasis. Both organisms are sometimes isolated from the same patient (Griffith et al, ARRD 1993, 147; 1271-8). In that circumstance, the clinical significance of M. abscessus may be difficult to determine. Between 2006 and the present we identified 53 patients treated for MAC lung disease who also had M. abscessus isolated from sputum. Patients were 92% female, age 73.2 ± 7.6 yrs and divided into 2 groups. Group 1 consisted of 32 patients not diagnosed with clinically significant M. abscessus infection. Group 1 had 1.4 ± 0.9 M. abscessus isolates per patient out of 39.3 ± 19.4 total cultures per patient. 25/32 (78%) patients had only 1 M. abscessus isolate. Group 2 consisted of 21 patients with clinically significant M. abscessus infection who had 15.0 ± 11.1 M. abscessus isolates per patient out of 41.7 ± 19.4 total cultures per patient (p < 0.001 vs Group 1). Group 1 patients had significantly more frequent isolation of other water-associated mycobacteria (M. gordonae, M. terrae, etc.) than Group 2 patients, 41% vs 14% (p < 0.05). There was no difference in the frequency of isolation of bronchiectasis-related bacterial pathogens (Pseudomonas, Stenotrophamonas, etc.) between Groups 1 and 2 (86% vs 81%). In Group 2, 11/21 (52%) patients were treated for M. abscessus infection including 5/9 (56%) diagnosed with concomitant MAC and M. abscessus infections. Determining the clinical significance of M. abscessus isolates in MAC lung disease patients is generally not difficult, however, due to the many challenges of of M. abscessus treatment, therapeutic decisions remain quite difficult.
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