Reassessment of the relevance between microbiological macrolide-induced resistance and diagnosis and treatment outcome of Mycobacterium abscessus-related pulmonary disease

Background: Treatment outcomes for Mycobacterium abscessus species-related pulmonary disease (MABS-PD) are generally poor because of inducible clarithromycin resistance (IR). The clinical management of patients with MABS with different genotypic and phenotypic susceptibility results is also not definitive. Here, we aimed to reassess the characteristics of patients with variant MABS and their association with diagnosis, treatment intervention, and sputum culture conversion. Methods: We retrospectively analyzed 119 patients with MABS infection. Clinical characteristics and medical history were obtained via medical chart review. Isolates were tested for clarithromycin susceptibility and classified into erm (41) sequevars. Results: In the IR, non-IR, and acquired resistance groups, the sputum culture conversion rates were 22% (5/23), 80% (40/50), and 8% (1/12), respectively. In contrast, in MAB, MAB T28, MAB C28, and M. abscessus subsp. massiliense (MAM), sputum culture conversion rates were 33% (12/36), 29% (22/31), 60% (3/5), and 70.8% (34/48), respectively. The proportion of patients with non-IR MAB T28 diagnosed and treated for MABS-PD was lower than those of patients with IR or acquired resistant T28 [35.7% (5/14), 80.7% (21/26), 100% (5/5); P < 0.05], whereas the sputum culture conversion rate was high in patients with non-IR MAB T28 [80.0%(4/5), 23.8%(5/21), 0%(0/5); P < 0.01)]. The sputum culture conversion rate in treated patients with MABS-PD with IR MAB C28 or acquired resistant MAM was low [0.0% (0/1) and 14.3% (1/7)]. Conclusions: Patients with MABS-PD and non-IR were likely to have sputum culture conversion. Our results indicated that phenotypical properties were associated with MABS-PD diagnosis and treatment.