Background/Aims: To analyze the characteristics of the sputum microbiota of patients with nontuberculous mycobacteria pulmonary disease (NTM-PD) based on treatment status. Methods: Twenty-eight sputum samples from 14 patients with NTM-PD, including 14 samples from the microbiologically cured group (7 at baseline and 7 during follow-up) and 14 from the treatment-refractory group (7 at baseline and 7 during follow-up) were included in this study. Bacterial microbiota was analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Results: Among the 14 patients, most had infections with Mycobacterium avium complex (n = 6), followed by Mycobacterium abscessus (n = 5); three patients exhibited mixed infection with both organisms. Alpha-diversity was higher in the cured group than in the treatment refractory group in both the baseline sputum (ACE, p = 0.005; Chao1, p = 0.010; Jackknife, p = 0.022, 0.043; Shannon, p = 0.048) and follow-up sputum (ACE, p = 0.018). Linear discriminant analysis effect size revealed that several taxa showed differential distributions based on treatment status. At the species level, Streptococcus pneumoniae, Prevotella melaninogenica, Haemophilus parahaemolyticus, Haemophilus haemolyticus, Fusobacterium nucleatum, Neisseria elongata, and Prevotella denticola were more abundant in sputum from the microbiologically cured group than in that from the refractory group (all p < 0.05). Conclusions In contrast to patients with treatment-refractory NTM-PD, those with stable disease without recurrence had higher microbial diversity in their sputum, including several predominant taxa.

Background/Aims: To analyze the characteristics of the sputum microbiota of patients with nontuberculous mycobacteria pulmonary disease (NTM-PD) based on treatment status. Methods: Twenty-eight sputum samples from 14 patients with NTM-PD, including 14 samples from the microbiologically cured group (7 at baseline and 7 during follow-up) and 14 from the treatment-refractory group (7 at baseline and 7 during follow-up) were included in this study. Bacterial microbiota was analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Results: Among the 14 patients, most had infections with Mycobacterium avium complex (n = 6), followed by Mycobacterium abscessus (n = 5); three patients exhibited mixed infection with both organisms. Alpha-diversity was higher in the cured group than in the treatment refractory group in both the baseline sputum (ACE, p = 0.005; Chao1, p = 0.010; Jackknife, p = 0.022, 0.043; Shannon, p = 0.048) and follow-up sputum (ACE, p = 0.018). Linear discriminant analysis effect size revealed that several taxa showed differential distributions based on treatment status. At the species level, Streptococcus pneumoniae, Prevotella melaninogenica, Haemophilus parahaemolyticus, Haemophilus haemolyticus, Fusobacterium nucleatum, Neisseria elongata, and Prevotella denticola were more abundant in sputum from the microbiologically cured group than in that from the refractory group (all p < 0.05). Conclusions In contrast to patients with treatment-refractory NTM-PD, those with stable disease without recurrence had higher microbial diversity in their sputum, including several predominant taxa.

Background/Aims: To analyze the characteristics of the sputum microbiota of patients with nontuberculous mycobacteria pulmonary disease (NTM-PD) based on treatment status. Methods: Twenty-eight sputum samples from 14 patients with NTM-PD, including 14 samples from the microbiologically cured group (7 at baseline and 7 during follow-up) and 14 from the treatment-refractory group (7 at baseline and 7 during follow-up) were included in this study. Bacterial microbiota was analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Results: Among the 14 patients, most had infections with Mycobacterium avium complex (n = 6), followed by Mycobacterium abscessus (n = 5); three patients exhibited mixed infection with both organisms. Alpha-diversity was higher in the cured group than in the treatment refractory group in both the baseline sputum (ACE, p = 0.005; Chao1, p = 0.010; Jackknife, p = 0.022, 0.043; Shannon, p = 0.048) and follow-up sputum (ACE, p = 0.018). Linear discriminant analysis effect size revealed that several taxa showed differential distributions based on treatment status. At the species level, Streptococcus pneumoniae, Prevotella melaninogenica, Haemophilus parahaemolyticus, Haemophilus haemolyticus, Fusobacterium nucleatum, Neisseria elongata, and Prevotella denticola were more abundant in sputum from the microbiologically cured group than in that from the refractory group (all p < 0.05). Conclusions In contrast to patients with treatment-refractory NTM-PD, those with stable disease without recurrence had higher microbial diversity in their sputum, including several predominant taxa.

Background/Aims: To analyze the characteristics of the sputum microbiota of patients with nontuberculous mycobacteria pulmonary disease (NTM-PD) based on treatment status. Methods: Twenty-eight sputum samples from 14 patients with NTM-PD, including 14 samples from the microbiologically cured group (7 at baseline and 7 during follow-up) and 14 from the treatment-refractory group (7 at baseline and 7 during follow-up) were included in this study. Bacterial microbiota was analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Results: Among the 14 patients, most had infections with Mycobacterium avium complex (n = 6), followed by Mycobacterium abscessus (n = 5); three patients exhibited mixed infection with both organisms. Alpha-diversity was higher in the cured group than in the treatment refractory group in both the baseline sputum (ACE, p = 0.005; Chao1, p = 0.010; Jackknife, p = 0.022, 0.043; Shannon, p = 0.048) and follow-up sputum (ACE, p = 0.018). Linear discriminant analysis effect size revealed that several taxa showed differential distributions based on treatment status. At the species level, Streptococcus pneumoniae, Prevotella melaninogenica, Haemophilus parahaemolyticus, Haemophilus haemolyticus, Fusobacterium nucleatum, Neisseria elongata, and Prevotella denticola were more abundant in sputum from the microbiologically cured group than in that from the refractory group (all p < 0.05). Conclusions In contrast to patients with treatment-refractory NTM-PD, those with stable disease without recurrence had higher microbial diversity in their sputum, including several predominant taxa.

Background/Aims: To analyze the characteristics of the sputum microbiota of patients with nontuberculous mycobacteria pulmonary disease (NTM-PD) based on treatment status. Methods: Twenty-eight sputum samples from 14 patients with NTM-PD, including 14 samples from the microbiologically cured group (7 at baseline and 7 during follow-up) and 14 from the treatment-refractory group (7 at baseline and 7 during follow-up) were included in this study. Bacterial microbiota was analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Results: Among the 14 patients, most had infections with Mycobacterium avium complex (n = 6), followed by Mycobacterium abscessus (n = 5); three patients exhibited mixed infection with both organisms. Alpha-diversity was higher in the cured group than in the treatment refractory group in both the baseline sputum (ACE, p = 0.005; Chao1, p = 0.010; Jackknife, p = 0.022, 0.043; Shannon, p = 0.048) and follow-up sputum (ACE, p = 0.018). Linear discriminant analysis effect size revealed that several taxa showed differential distributions based on treatment status. At the species level, Streptococcus pneumoniae, Prevotella melaninogenica, Haemophilus parahaemolyticus, Haemophilus haemolyticus, Fusobacterium nucleatum, Neisseria elongata, and Prevotella denticola were more abundant in sputum from the microbiologically cured group than in that from the refractory group (all p < 0.05). Conclusions In contrast to patients with treatment-refractory NTM-PD, those with stable disease without recurrence had higher microbial diversity in their sputum, including several predominant taxa.

Background: The Xpert MTB/RIF Ultra (Xpert Ultra) was introduced to enhance the sensitivity of tuberculosis detection, particularly in smear-negative cases, compared with its predecessor, Xpert MTB/RIF (Xpert). However, its performance in high-resource, intermediateburden settings remains unassessed. We prospectively compared the diagnostic accuracy of Xpert Ultra and Xpert for detecting Mycobacterium tuberculosis (MTB) and rifampin resistance in Korea. Methods: In total, 309 respiratory specimens were analyzed using both assays. We used two reference standards: mycobacterial culture and a composite reference standard based on clinical diagnosis and treatment decisions. Diagnostic performance, including sensitivity, specificity, and agreement between the two assays, was assessed. Spiking experiments using 13 MTB isolates with known rpoB mutations were performed to evaluate rifampin resistance detection. Results: Xpert Ultra showed increased, albeit not significantly, sensitivity (73.7% vs. 65.8% with culture; 63.8% vs. 53.2% with the composite reference standard) over Xpert. Its specificity was comparable to that of Xpert; however, a few false-positive results were observed among trace- and very low-positives. Among six culture-negative but Xpert Ultra-positive cases, two were clinically diagnosed as tuberculosis. Of the 13 rpoB mutant strains, Xpert correctly detected all mutations in the rifampin resistance-determining region, whereas Xpert Ultra yielded indeterminate results for Q432P and Q429H/L430P/H445Q. Conclusions Xpert Ultra tends to have increased sensitivity; however, it shows potential diagnostic ambiguity associated with trace- or very low-positive results. These findings highlight the importance of clinical correlation, particularly in culture-negative cases. Indeterminate results in certain rpoB mutations require cautious interpretation.

Limited data are available regarding the in vitro activity of SPR719, a derivative of benzimidazole, against diverse nontuberculous mycobacteria (NTM) species. We investigated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of SPR719 against clinical NTM isolates, including clarithromycin- and amikacin-resistant strains. NTM isolates were obtained from patients with NTM-pulmonary disease caused by various NTM species, including Mycobacterium avium complex, M. abscessus (subspecies abscessus and massiliense), M. kansasii, and M. fortuitum. Regardless of clarithromycin or amikacin resistance, the MIC and MBC values of SPR719 were comparable among these major pathogenic NTM species. In over 70% of the isolates, the MIC values were ≤ 2 µg/mL with MBC values of ≤ 4 µg/mL. The MIC and MBC values of M. kansasii were relatively lower than those of the other species with little difference between them, demonstrating the bactericidal properties of SPR719. The in vitro activity of SPR719 against major clinical NTM species suggests that SPR719 can serve as a novel treatment option for NTM-pulmonary disease.

Nontuberculous mycobacteria are mycobacteria other than those that cause tuberculosis and leprosy and can cause infections in various parts of the body, predominantly the lungs. Of approximately 200 species of nontuberculous mycobacteria, only about 10 are linked to pulmonary infections, with Mycobacterium avium complex (MAC) being the most common.Current Concepts: The standard treatment for pulmonary diseases caused by the MAC is combination therapy, including macrolide antibiotics and other antibiotics such as ethambutol and rifampin. Among macrolide antibiotics, azithromycin and clarithromycin are commonly used for managing MAC pulmonary diseases, and in cases with extensive lesions, amikacin injections are administered concurrently during the initial stages of treatment. Ensuring an overall treatment duration of an additional 12 months after negative culture conversion is recommended in affected patients. However, despite an extended treatment period, the cure rate remains at 60~70%. Recently, an inhalable liposomal form of amikacin, marketed as ARIKAYCE, has been developed. It has been approved by the US Food and Drug Administration as an effective treatment for refractory MAC pulmonary diseases. When ARIKAYCE was used for an additional 6 months or more in patients with refractory MAC pulmonary diseases, approximately 29% of patients achieved additional treatment success. However, it has yet to be officially imported into South Korea, and a high monthly cost restricts its practical use in the country. Therefore, the treatment of MAC pulmonary disease in South Korea will remain a challenge, unless a more effective treatment emerges.Discussion and Conclusion: MAC pulmonary disease requires long-term combination antibiotic therapy, usually with macrolides, ethambutol, and rifampin, and amikacin injections are recommended for cases with extensive lesions. The lack of effective drugs hampers treatment, increasing the burden of antibiotic side effects. Therefore, more research is urgently needed for better treatment of MAC pulmonary disease.

The aim of our study was to investigate the incidence of and risk factors for coronavirus disease 2019 (COVID-19) in patients with non-tuberculous mycobacterial-pulmonary disease (NTM-PD). A total of 3,866 patients with NTM-PD were retrospectively identified from a single center. Compared to the general population of Korea, patients with NTM-PD had a substantially increased age-standardized incidence of COVID-19 from January 2020 to February 2021 (2.1% vs. 0.2%). The odds of being infected with COVID-19 was particularly higher in patients who received treatment for NTM-PD than in those who did not receive treatment for NTM-PD (adjusted odd ratio = 1.99, 95% confidence interval = 1.09–3.64, P = 0.026). Patients with NTM-PD might be regarded as a high-risk group for COVID-19 and may need a more proactive preventive strategy for COVID-19 and other pandemics in the future.