Minimum Inhibitory Concentrations before and after Antibacterial Treatment in Patients with Mycobacterium abscessus Pulmonary Disease.

The clinical importance of Mycobacterium abscessus (MABS) pulmonary disease has been increasing. However, there is still a lack of information about MIC distribution patterns and changes in clinical practice settings. The MIC results of rapidly growing mycobacteria isolated from 92 patients with nontuberculous mycobacterial pulmonary disease diagnosed from May 2019 to March 2021 were retrospectively analyzed. Most of the patients (86 patients; 93.5%) were infected with MABS; 46 with Mycobacterium abscessus subsp. abscessus (Mab), and 40 with Mycobacterium abscessus subsp. massiliense (Mma). Significant differences in susceptibility to clarithromycin (15.2% versus 80.0%, P < 0.001) and azithromycin (8.7% versus 62.5%, P < 0.001) were observed between Mab and Mma. Most isolates were susceptible to amikacin (80; 93.0%), and over half were susceptible to linezolid (48; 55.8%). Only one-quarter of isolates (22, 25.6%) were susceptible to imipenem, while more than half (56; 65.1%) had intermediate susceptibility. Fifty-one isolates (59.3%) had MIC values of less than 1 µg/mL for sitafloxacin, which were significantly higher than isolates for moxifloxacin (5; 5.8%), especially in Mab. Sixty-five (75.6%) isolates had MICs of less than 0.5 µg/mL to clofazimine. Two patients showed obvious MIC result changes: from susceptible to resistant to clarithromycin and from resistant to susceptible to amikacin and imipenem. In conclusion, MABS isolates were relatively susceptible to amikacin and linezolid, and clarithromycin and azithromycin were especially effective against Mma. In addition, sitafloxacin and clofazimine had low MICs and might be effective treatment agents. IMPORTANCE The MICs of isolates from 86 patients with Mycobacterium abscessus (MABS); 46 with Mycobacterium abscessus subsp. abscessus (Mab), and 40 with Mycobacterium abscessus subsp. massiliense (Mma) were retrospectively analyzed. The main findings are as follows: (i) Mma were significantly more susceptible to clarithromycin and azithromycin than Mab, and both subspecies tended to be more susceptible to clarithromycin than azithromycin. (ii) Most isolates were susceptible to amikacin (93.0%), and over half to linezolid (55.8%). (iii) Fifty-one isolates (59.3%) had MIC values of less than 1 µg/mL for sitafloxacin, and 65 (75.6%) had less than 0.5 µg/mL for clofazimine, which seems worth clinical investigating. (iv) Among nine cases analyzed chronological changes, only two patients showed obvious MIC result changes even after the long-term multidrug treatment. The present study revealed MICs of MABS clinical isolates before and after treatment in clinical settings, which could help develop future MABS treatments strategies.

[Miss-management in treatment failure of pulmonary tuberculosis].

PURPOSE: To investigate the risk factor of treatment failure of pulmonary tuberculosis excluding multi-drug resistant cases from the standpoint of both clinical management and tuberculosis control. OBJECT AND METHOD: Retrospective chart review of patients who admitted to Fukujuji Hospital for treatment failure of pulmonary tuberculosis excluding multi-drug resistant cases from Jan. 1993 to Dec. 2003. RESULTS: Out of 24 treatment failure cases available for analysis, 4 cases were associated with chronic tuberculous empyema with broncho-pleural fistula, and among them, chronic empyema was considered to be the main cause of treatment failure in one case. In 6 cases, poor adherence to medication was confirmed or suspected, and 2 of these 6 cases was also associated with miss-management. In 9 cases miss-management was found without poor adherence or chronic empyema, and in 8 out of these 9 cases, miss-management was considered to be the main cause of treatment failure. In 5 cases no apparent risk factor was found, but in 2 out of these 5 cases the ignorance of the results of drug sensitivity tests (and, therefore, miss-management) was strongly suspected. Summing up, in 10 out of 24 cases (41.7%), the miss-management was considered to be the main cause of treatment failure, and it was more frequently seen than poor adherence to medication. CONCLUSION: Clinicians should be aware of these risk factors of treatment failure such as chronic empyema, weak regimen in bacteriological negative cases, rifampicin+ethambutol regimen, and miss-management of drug adverse effect. From the standpoint of tuberculosis control in Japan we considered that, in addition to DOT, strategy to secure the quality of tuberculosis treatment is by all means needed.