Beyond Symptoms: Radiologic identification of asymptomatic Mycobacterium avium complex pulmonary infections.

BACKGROUND: Although international nontuberculous mycobacterial pulmonary disease (NTM-PD) guidelines highlight symptom presence at diagnosis, the clinical characteristics of asymptomatic Mycobacterium avium complex pulmonary infection (MAC-PI) patients remain understudied. We clarified the clinical characteristics and course of asymptomatic MAC-PI patients. METHODS: We retrospectively analyzed 200 consecutive patients with MAC-PIs and adequate available data who newly met the microbiological and radiological criteria for NTM-PD at Fukujuji Hospital from January 2018 to June 2020. We compared the clinical characteristics and course of asymptomatic patients with symptomatic patients and evaluated factors influencing treatment initiation through multivariate analysis. RESULTS: 111 patients were symptomatic and 89 were asymptomatic at diagnosis. While the proportion was significantly lower than that in the symptomatic group (28.8 %), 15.7 % of asymptomatic group patients had cavitary lesions (P = 0.042). In the asymptomatic group, treatments were initiated in 38 (42.7 %) patients, and cavitary lesions, a positive acid-fast bacilli smear, and younger age were independent risk factors for treatment initiation. Among 22 (57.9 %) patients who experienced disease progression necessitating treatment during follow-up, 13 (34.2 %) displayed radiological progression without any worsening of symptoms. Agents used for treatment were consistent across the groups, with no significant differences in culture conversion, microbiological recurrence rates, or spontaneous culture conversion rates. CONCLUSION: Routine health checkups and radiological examinations can detect clinically important MAC-PIs even in the absence of symptoms. Considering that the clinical course of asymptomatic MAC-PI patients is largely similar to that of symptomatic patients, timely and appropriate management and intervention are essential for all MAC-PI patients.

Activities of Daily Living, Hypoxemia, and Lymphocytes Score for Predicting Mortality Risk in Patients With Pulmonary TB.

BACKGROUND: A clinically applicable mortality risk prediction system for pulmonary TB may improve treatment outcomes, but no easy-to-calculate and accurate score has yet been reported. The aim of this study was to construct a simple and objective disease severity score for patients with pulmonary TB. RESEARCH QUESTION: Does a clinical score consisting of simple objective factors predict the mortality risk of patients with pulmonary TB? STUDY DESIGN AND METHODS: The data set from our previous prospective study that recruited patients newly diagnosed with pulmonary TB was used for the development cohort. Patients for the validation cohort were prospectively recruited between March 2021 and September 2022. The primary end point was all-cause in-hospital mortality. Using Cox proportional hazards regression, a mortality risk prediction model was optimized in the development cohort. The disease severity score was developed by assigning integral points to each variate. RESULTS: The data from 252 patients in the development cohort and 165 patients in the validation cohort were analyzed, of whom 39 (15.5%) and 17 (10.3%), respectively, died in the hospital. The disease severity score (named the AHL score) included three clinical parameters: activities of daily living (semi-dependent, 1 point; totally dependent, 2 points); hypoxemia (1 point), and lymphocytes (< 720/µL, 1 point). This score showed good discrimination with a C statistic of 0.902 in the development cohort and 0.842 in the validation cohort. We stratified the score into three groups (scores of 0, 1-2, and 3-4), which clearly corresponded to low (0% and 1.3%), intermediate (13.5% and 8.9%), and high (55.8% and 39.3%) mortality risk in the development and validation cohorts. INTERPRETATION: The easy-to-calculate AHL disease severity score for patients with pulmonary TB was able to categorize patients into three mortality risk groups with great accuracy. CLINICAL TRIAL REGISTRATION: University Hospital Medical Information Network Center; No. UMIN000012727 and No. UMIN000043849; URL: www.umin.ac.jp.

Multiple bacterial culture positivity reflects the severity and prognosis as bronchiectasis in Mycobacterium avium complex pulmonary disease.

BACKGROUND: Bacterial coinfections are observed in 19-66% of patients with Mycobacterium avium complex pulmonary disease (MAC-PD) during the entire duration of the disease. The impact of bacterial coinfection at diagnosis on the clinical course of MAC-PD has not been reported. METHODS: Among 558 patients diagnosed with MAC-PD between January 2016 and December 2020, 218 patients who underwent sputum culture tests twice or more within one year before and after diagnosis were included. We compared the patient characteristics and disease courses between the patients who had the same bacterial species detected twice or more (bacterial culture positive group: BCP group) and those who never had bacteria cultured (bacterial culture negative group: BCN group). RESULTS: We included 70 patients in the BCP group and 74 in the BCN group. The radiological findings showed that BCP at diagnosis correlated with a high modified Reiff score. During the median follow-up period of 42 months, the patients in the BCP group were more likely to accomplish spontaneous sputum conversion of MAC. The treatment initiation rate for MAC-PD in the BCP group was lower than that in the BCN group (41.4% vs. 67.6%, P = 0.003). In contrast, the time to the first bronchiectasis exacerbation in the BCP group was shorter than that in the BCN group, and the frequency of bronchiectasis exacerbations was higher in the BCP group. CONCLUSIONS: Patients with BCP at diagnosis are less likely to initiate treatment for MAC-PD and more likely to develop bronchiectasis exacerbation.

Epidemiological characteristics of nontuberculous mycobacteriosis and bronchiectasis: comparative study using national mortality statistics from 1970 to 2015 in Japan.

Background: This study assessed longitudinal national data on mortality due to nontuberculous mycobacteriosis (NTMosis) and bronchiectasis and the association between the two diseases. Methods: We analysed the national death statistics of Japan from 1970 to 2015. The International Classification of Disease (ICD) codes were used to extract the relevant data. Crude mortality, age-adjusted mortality and standardised mortality rates were calculated using vital statistics and the population in 2000. We also identified domestic publications related to NTMosis and bronchiectasis with an internet-based search system. Results: The total number of bronchiectasis-related deaths remained at the same level, which was approximately 1000, for 45 years, although the number of deaths has consistently decreased in males but increased in females since the mid-1990s. A substantial increasing trend in females was also observed for NTMosis in the same period. The age-adjusted mortality data showed an increase in mortality in women due to NTMosis and confirmed the trend in bronchiectasis in women. The patterns in the number of domestic reports showed a recent slight increase in bronchiectasis and a marked increase in NTMosis. Conclusions: The trends in bronchiectasis-related mortality differed by sex. The epidemiological trends in the two diseases were associated, especially in elderly females since the mid-1990s. It is suggested that pulmonary NTMosis without pre-existing bronchiectasis might be a leading cause of postinfectious bronchiectasis in Japan.

Pharmacokinetics and Adverse Effects of Clofazimine in the Treatment of Pulmonary Non-Tuberculous Mycobacterial Infection.

Clofazimine (CFZ) is used to treat pulmonary non-tuberculous mycobacterial (NTM) infection; however, its pharmacokinetics remain unexplored in patients with pulmonary NTM, and the relationship between CFZ serum concentration and adverse effects has not been investigated. The objectives of this study were to characterize the pharmacokinetics of CFZ in pulmonary NTM disease treatment and to investigate the relationship between the steady-state CFZ serum concentration and adverse effects. A prospective observational study was conducted on 45 patients with pulmonary NTM treated with CFZ (UMIN000041053). A maximum of five serum samples per patient were taken at the CFZ trough, and serum concentration was measured using high-performance liquid chromatography-mass spectrometry (HPLC-MS). The pharmacokinetics of CFZ were analyzed using a nonlinear mixed effect model. The relationships among steady-state CFZ serum concentration and adverse effects, pigmentation, and heart rate-corrected QT (QTc) interval were investigated. Twenty-six patients had M. avium or M. intracellulare infection and nineteen had M. abscessus infection. The primary CFZ dosage was 50 mg/day. The estimated apparent CFZ clearance, apparent volume of distribution, and half-life were 2.4 L/h, 2,960 L, and 36 days, respectively. The combined use of rifampicin and CFZ significantly reduced CFZ exposure by 22%. Although there was no relationship between CFZ serum concentration and pigmentation intensity, the QTc interval was significantly correlated with CFZ serum concentration. The estimation of accurate pharmacokinetics for CFZ required approximately 5 months of monitoring. The relationship between the serum concentration and specific adverse effects of CFZ confirmed that CFZ serum concentration was not associated with pigmentation but did affect the QTc interval.

Low-dosage ethambutol, less than 12.5 mg/kg/day, does not worsen the clinical outcomes of pulmonary Mycobacterium avium and Mycobacterium intracellulare disease: a retrospective cohort study.

OBJECTIVES: Multidrug chemotherapy is recommended for treating pulmonary Mycobacterium avium and Mycobacterium intracellulare disease. Although ethambutol has been demonstrated to inhibit macrolide resistance, the ethambutol dosage is sometimes decreased due to concerns about optic neuropathy. We aimed to assess whether lower ethambutol doses impact treatment outcomes. METHODS: Patients treated over 12 months between 2016 and 2020 were collected retrospectively. Clinical outcomes, including negative culture conversion, microbiological cure, adverse events, resistance to macrolides, and recurrence, were compared according to daily ethambutol dosage. RESULTS: Among 146 patients, 42 were treated with ethambutol dosages over 12.5 mg/kg/day, and 104 were treated with lower dosages. Negative culture conversion was achieved for 125 patients, and 90 patients achieved microbiological cure. Recurrence was identified in 16 patients who achieved microbiological cure. No macrolide resistance was observed, and no significant difference was observed in the percentage of negative culture conversion (P = 1.00) or microbiological cure (P = 0.67) between the high- and low-dosage ethambutol groups. Sputum smear positivity was associated with a lower adjusted odds ratio (aOR) of negative culture conversion (aOR: 0.48, 95% CI: 0.29-0.80). A lower aOR of microbiological cure was independently associated with sputum smear positivity (aOR: 0.52, 95% CI: 0.37-0.74) and with the use of an intermittent regimen (aOR: 0.60, 95% CI: 0.41-0.87). Daily ethambutol dosage was not identified as a prognostic factor for any of the outcomes. Optic neuropathy was observed in 7.1% of the high-dose ethambutol group and 1.0% of the low-dosage ethambutol group (P = 0.07). CONCLUSION: An ethambutol dosage of 12.5 mg/kg/day or less in guideline-based chemotherapy may reduce optic neuropathy without worsening clinical outcomes.

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.

Analysis of risk factors for the development of a post-bronchoscopy respiratory infection in lung cancer patients.

BACKGROUND: The development of pneumonia following bronchoscopy is a very important post-bronchoscopic complication, while lung abscesses after bronchoscopy are rare. However, bronchoscopic techniques have advanced, and recently, we have observed patients with lung abscess after bronchoscopy. Therefore, the risk factors might vary from those in past reports. This study was performed to identify the incidence of and risk factors for post-bronchoscopy respiratory infections. METHODS: We retrospectively studied adult patients diagnosed with lung cancer by bronchoscopy at Fukujuji Hospital from January 2017 to June 2019. The infection and noninfection groups were compared. The incidence of lung abscess was compared between recent periods and 2013, when endobronchial ultrasonography with a guide sheath (EBUS-GS) was not yet used in our hospital. RESULTS: We reviewed 327 patients, including 20 patients (6.1%) with infections. The risk factors for infection were necrosis and/or a cavity in the tumor (p < 0.001), a large tumor diameter (≥30 mm) (p = 0.010), and a low serum albumin level (<4.0 g/dL) (p = 0.010). We developed a predictive score with these risk factors, and the area under the curve was 0.737 (95% Cl: 0.610-0.864). No significant differences in age, current smoking status, or abnormal bronchoscopic findings were observed, although these were previously reported as risk factors. In total, 12 patients had lung abscesses (3.7%), which is a higher incidence than that in 2013 (0.8%). CONCLUSIONS: The risk factors for developing post-bronchoscopy respiratory infection in our study varied from those in past reports, possibly because of the advancements in bronchoscopic techniques, such as EBUS-GS.

Clinical risk factors related to treatment failure in Mycobacterium abscessus lung disease.

The clinical importance of Mycobacterium abscessus subsp. abscessus (M. abscessus) lung disease has been increasing, but few studies have assessed the clinical characteristics associated with the treatment outcome. We retrospectively analyzed 75 consecutive patients with M. abscessus lung disease diagnosed at a tertiary hospital from January 2004 to April 2018. Among 52 patients with sufficient clinical data, 19 patients (42.2%) achieved treatment success. Compared with 26 (57.8%) patients in the treatment failure group, body mass index (BMI) (19.8 vs 17.5 kg/m2, P = 0.022), previous nontuberculous mycobacterial (NTM) lung disease (26.3% vs 61.5%, P = 0.034), the presence of cavitary lesions (31.6% vs 69.2%, P = 0.017), and the bronchiectasis score (3.0 vs 5.0, P = 0.003) were significantly different in the treatment success group. Multivariate analysis showed that age (adjusted hazard ratio (aHR), 0.94; 95% confidence interval (CI), 0.90 to 0.99; P = 0.010), the presence of cavitary lesions (aHR, 0.34; 95% CI, 0.12 to 0.94; P = 0.039), and previous NTM lung disease (aHR, 0.28; 95% CI, 0.09 to 0.86; P = 0.026) were negatively associated with treatment success. This is the first study to show that previous NTM lung disease might be a clinically important factor related to unfavorable treatment outcomes in M. abscessus lung disease patients. To increase our understanding the characteristics of M. abscessus lung disease, this factor should be independently analyzed in future research.

Mycobacterium europaeum lung disease in an immunocompetent patient without underlying lung disease.

Mycobacterium europaeum (M. europaeum) was recently identified as a nontuberculous mycobacterium belonging to the Mycobacterium simiae complex. There have been only a few reported cases of M. europaeum lung disease, all of which occurred in patients with immunodeficiency or prior lung disease. We herein report a case of M. europaeum lung disease in an otherwise healthy Japanese individual. A 70-year-old woman who had no apparent immunodeficiency or medical history was diagnosed with M. europaeum lung disease by multiple positive sputum cultures. The patient was successfully treated with clarithromycin, rifampin, ethambutol, and amikacin. This report is the first case of M. europaeum lung disease occurring in an individual without predisposing risk factors.