Mycobacterial spindle cell pseudotumor of the spinal cord: Case report and literature review.

We report the first description of spinal cord mycobacterial spindle cell pseudotumor. A patient with newly diagnosed advanced HIV presented with recent-onset bilateral leg weakness and was found to have a hypermetabolic spinal cord mass on structural and molecular imaging. Biopsy and cultures from blood and cerebrospinal fluid confirmed spindle cell pseudotumor due to Mycobacterium avium-intracellulare. Despite control of HIV and initial reduction in pseudotumor volume on antiretrovirals and antimycobacterials (azithromycin, ethambutol, rifampin/rifabutin), he ultimately experienced progressive leg weakness due to pseudotumor re-expansion. Here, we review literature and discuss multidisciplinary diagnosis, monitoring and management challenges, including immune reconstitution inflammatory syndrome.

Clofazimine as a substitute for rifampicin improves efficacy of Mycobacterium avium pulmonary disease treatment in the hollow-fiber model.

Mycobacterium avium complex pulmonary disease is treated with an azithromycin, ethambutol, and rifampicin regimen, with limited efficacy. The role of rifampicin is controversial due to inactivity, adverse effects, and drug interactions. Here, we evaluated the efficacy of clofazimine as a substitute for rifampicin in an intracellular hollow-fiber infection model. THP-1 cells, which are monocytes isolated from peripheral blood from an acute monocytic leukemia patient, were infected with M. avium ATCC 700898 and exposed to a regimen of azithromycin and ethambutol with either rifampicin or clofazimine. Intrapulmonary pharmacokinetic profiles of azithromycin, ethambutol, and rifampicin were simulated. For clofazimine, a steady-state average concentration was targeted. Drug concentrations and bacterial densities were monitored over 21 days. Exposures to azithromycin and ethambutol were 20%-40% lower than targeted but within clinically observed ranges. Clofazimine exposures were 1.7 times higher than targeted. Until day 7, both regimens were able to maintain stasis. Thereafter, regrowth was observed for the rifampicin-containing regimen, while the clofazimine-containing regimen yielded a 2 Log10 colony forming unit (CFU) per mL decrease in bacterial load. The clofazimine regimen also successfully suppressed the emergence of macrolide tolerance. In summary, substitution of rifampicin with clofazimine in the hollow-fiber model improved the antimycobacterial activity of the regimen. Clofazimine-containing regimens merit investigation in clinical trials.

OPTIMA: An Open-Label, Noncomparative Pilot Trial of Inhaled Molgramostim in Pulmonary Nontuberculous Mycobacterial Infection.

Rationale: Inhaled granulocyte-macrophage colony-stimulating factor (GM-CSF) has been proposed as a potential immunomodulatory treatment for nontuberculous mycobacterial (NTM) infection.Objectives: This open-label, noncomparative pilot trial investigated the efficacy and safety of inhaled GM-CSF (molgramostim nebulizer solution) in patients with predominantly treatment-refractory pulmonary NTM infection (Mycobacterium avium complex [MAC] and M. abscessus [MABS]), either in combination with ongoing guideline-based therapy (GBT) or as monotherapy in patients who had stopped GBT because of lack of efficacy or intolerability.Methods: Thirty-two adult patients with refractory NTM infection (MAC, n = 24; MABS, n = 8) were recruited into two cohorts: those with (n = 16) and without (n = 16) ongoing GBT. Nebulized molgramostim 300 µg/d was administered over 48 weeks. Sputum cultures and smears and clinical assessments (6-min-walk distance, symptom scores, Quality of Life-Bronchiectasis Questionnaire score, and body weight) were collected every 4 weeks during treatment and 12 weeks after the end of treatment. The primary endpoint was sputum culture conversion, defined as three consecutive monthly negative cultures during the treatment period.Results: Eight patients (25%) achieved culture conversion on treatment (seven [29.2%] patients with MAC infection, one [12.5%] patient with MABS infection); in four patients, this was durable after the end of treatment. Of the 24 patients with MAC infection, an additional 4 patients had a partial response, converting from smear positive at baseline to smear negative at the end of treatment, and time to positivity in liquid culture media increased. Two of these patients sustained negative cultures from the end of treatment. Other clinical endpoints were unchanged. Serious adverse events were mainly pulmonary exacerbations or worsening NTM infection. Three deaths, not treatment related, were reported.Conclusions: In this population of patients with severe NTM disease, molgramostim was safe and well tolerated. Sputum culture conversion rates for patients with MAC infection (29.2%) were greater than reported for similar refractory MAC cohorts managed with GBT alone. Less benefit was seen for MABS infection. No serious safety concerns were identified. Further evaluation in a larger cohort is warranted.Clinical trial registered with www.clinicaltrials.gov (NCT03421743).

Pulmonary nocardiosis following nodular bronchiectatic Mycobacterium avium complex pulmonary disease in an immunocompetent patient.

A woman in her 70s with a history of nodular bronchiectatic Mycobacterium avium complex pulmonary disease (MAC-PD) presented with an exacerbated productive cough and worsening findings on chest imaging. Although repeated sputum culture tests were negative for acid-fast bacilli and only revealed normal respiratory flora, a bronchoscopy identified Nocardia sp. Consequently, she was diagnosed with pulmonary nocardiosis and was successfully treated with levofloxacin. It is known that pulmonary nocardiosis can manifest in immunocompetent individuals with bronchiectasis. For cases of refractory nodular bronchiectatic MAC-PD, it is vital to consider bronchoscopy to identify potential co-infections, such as Nocardia.

Comparison of treatment outcomes between intermittent and daily regimens in non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease in relation to sputum smear results: a retrospective cohort study.

This study retrospectively analyzed the treatment outcomes of 110 patients with non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease who received intermittent or daily treatment with a three-drug oral antibiotic regimen (i.e., a macrolide, ethambutol, and rifampin) at a tertiary referral center in South Korea. Among these patients, 36 had sputum smear positivity. Of these 36 patients, intermittent treatment led to a lower culture conversion rate than daily treatment [50.0% (8/16) vs 85.0% (17/20), P = 0.034].

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.

Unravelling the mystery of a rare infection: a challenging case of pulmonary sequestration with Mycobacterium avium complex and the importance of a thorough microbiological investigation.

Pulmonary sequestration is a rare congenital condition. It is a dysplastic lung tissue with a separate systemic blood supply and without a bronchial tree connection. The emergence of a superimposed infection can lead to its diagnosis, such as Staphylococcus aureus, Pseudomonas aeruginosa, Nocardia asteroids and Aspergillus sp pneumonia. Mycobacterium avium complex (MAC) superimposed disease is exceedingly rare. We report a case of a man in his third decade without known medical disorders presenting with a persistent cough. After an extensive microbiological workup, an MAC infection was diagnosed. An elevated carbohydrate antigen 19-9 (CA 19-9) was also noted. He was treated with antimycobacterial therapy and lobectomy resulting in clinical improvement and CA19-9 normalisation. This case illustrates the value of comprehensive microbiological investigations in patients with chronic respiratory symptoms and imaging findings that are not typical of bacterial pneumonia. Clinical studies remain needed to investigate the utility of CA 19-9 in a scoring system to guide MAC therapy.

Disseminated coinfection with Mycobacterium Avium complex and Mycobacterium Kansasii in a patient with idiopathic CD4+ lymphocytopenia: A case report.

Simultaneously disseminated coinfection with two species of nontuberculous mycobacteria (NTM) is extremely rare and had been reported only in immunocompromised individuals. Here, we report a 59-year-old Thai man, previously healthy. He presented with a 2-month history of prolonged fever, constitutional symptoms, and hepatosplenomegaly. His chest and abdomen computed tomography illustrated multiple enlarged mediastinal lymph nodes accompanied with multifocal crazy-paving appearance in both lungs and hepatosplenomegaly. Endobronchial ultrasound-guided transbronchial needle aspiration was performed on the mediastinal nodes. The pathologic findings were necrotizing granulomatous lymphadenitis with numerous AFB-positive bacilli. Blood culture subsequently isolated M. intracellulare, while BAL and lymph node culture isolated M. intracellulare and M. kansasii, which confirmed species by multiplex PCR and 16s rRNA sequencing. Idiopathic CD4+ lymphocytopenia (ICL) was diagnosed as the cause of secondary immune deficiency. Intravenous imipenem, amikacin, and azithromycin were administered as an empirical antibiotic regimen for 4 weeks, then substituted to oral rifampicin, clarithromycin, moxifloxacin, and ethambutol as definitive regimen. Unfortunately, it was found that he had died unexpectedly at home after 4 months of treatment, possibly related to this illness. In our view, patients with severe disseminated NTM disease should be evaluated to explore a secondary immune deficiency disorder. An ICL is a rare heterogenous syndrome but should be considered.

Haemorrhagic Mycobacterium avium complex pericarditis presenting with cardiac tamponade in an immunocompetent woman.

A young woman in her mid-40s was referred by her primary care physician for fever, worsening shortness of breath, pleuritic chest pain and tachycardia. CT angiogram of the chest revealed a large pericardial effusion. Echocardiogram confirmed tamponade physiology despite her being haemodynamically stable. She had an emergency pericardiocentesis which revealed evidence of a haemorrhagic pericardial effusion. However, the patient was still symptomatic after treatment and had to undergo video-assisted thoracoscopic surgery with a pericardial window and chest tube. Postoperatively, her fevers resolved. Pan-culture was initially negative, and all antibiotics were discontinued. Acid-fast bacilli cultures later grew Mycobacterium avium complex. She continued to have chest discomfort postoperatively, but follow-up CT of the chest 3 months postoperatively showed continued resolution of her pericardial effusion. The patient's symptoms improved, and she has had no recurrence of effusion without the need for anti-tuberculosis drugs.

Risk factors for clinical progression in patients with pulmonary Mycobacterium avium complex disease without culture-positive sputum: a single-center, retrospective study.

OBJECTIVES: Limited data are available on the progression of pulmonary Mycobacterium avium complex (MAC) disease without culture-positive sputum. The aim of this study was to identify the risk factors associated with clinical progression of pulmonary MAC disease diagnosed by bronchoscopy. METHODS: A single-center, retrospective, observational study was conducted. Pulmonary MAC patients diagnosed by bronchoscopy without culture-positive sputum from January 1, 2013, to December 31, 2017 were analyzed. Clinical progression after diagnosis was defined as having culture-positive sputum at least once or initiation of guideline-based therapy. Then, clinical characteristics were compared between clinically progressed patients and stable patients. RESULTS: Ninety-three pulmonary MAC patients diagnosed by bronchoscopy were included in the analysis. During the 4-year period after diagnosis, 38 patients (40.9%) started treatment, and 35 patients (37.6%) had new culture-positive sputum. Consequently, 52 patients (55.9%) were classified into the progressed group, and 41 patients (44.1%) were classified into the stable group. There were no significant differences between the progressed and the stable groups in age, body mass index, smoking status, comorbidities, symptoms, or species isolated from bronchoscopy. On multivariate analysis, male sex, monocyte to lymphocyte ratio (MLR) ≥ 0.17, and the presence of combined lesions in the middle (lingula) and lower lobes were risk factors for clinical progression. CONCLUSIONS: Some patients with pulmonary MAC disease without culture-positive sputum progress within 4 years. Therefore, pulmonary MAC patients, especially male patients, having higher MLR or lesions in the middle (lingula) and lower lobes might need careful follow-up for a longer time.

Mycobacterium Avium Complex Infection of the Spine in a Patient Without Acquired Immune Deficiency Syndrome: A Case Report and Literature Review.

A 52-year-old patient misdiagnosed with spinal tuberculosis was successfully diagnosed with Mycobacterium avium infection using metagenomic next-generation sequencing and cured with four-drug combination protocol chemotherapy (amikacin, rifampicin, clarithromycin, ethambutol) and spinal fixation.

Patient-Reported Symptom and Health-Related Quality-of-Life Validation and Responsiveness During the First 6 Months of Treatment for Mycobacterium avium Complex Pulmonary Disease.

BACKGROUND: Nontuberculous mycobacteria (NTM), predominately Mycobacterium avium complex (MAC), cause chronic pulmonary disease. Improvements in symptoms and health-related quality of life (HRQoL) are important treatment outcomes, but no validated patient-reported outcome (PRO) measure exists. RESEARCH QUESTION: What are the validity and responsiveness of the Quality of Life-Bronchiectasis (QOL-B) questionnaire respiratory symptoms scale and key HRQoL measures during the first 6 months of MAC pulmonary disease (MAC-PD) treatment? STUDY DESIGN AND METHODS: Comparison of Two- vs Three-antibiotic Therapy for Pulmonary Mycobacterium Avium Complex Disease (MAC2v3) is an ongoing randomized, multisite pragmatic clinical trial. Patients with MAC-PD were randomized to azithromycin-based two-drug or three-drug therapy; treatment groups were combined for this analysis. PROs were measured at baseline, 3 months, and 6 months. The QOL-B respiratory symptoms, vitality, physical functioning, health perceptions, and NTM symptom domain scores (on a scale of 0-100, with 100 being best) were analyzed separately. We performed psychometric and descriptive analyses in the population enrolled as of the time of analysis and calculated the minimal important difference (MID) using distribution-based methods. Finally, we evaluated responsiveness using paired t tests and latent growth curve analysis in the subset with longitudinal surveys completed by the time of analysis. RESULTS: The baseline population included 228 patients, of whom 144 had completed longitudinal surveys. Patients predominately were female (82%) and had bronchiectasis (88%); 50% were 70 years of age or older. The respiratory symptoms domain showed good psychometric properties (no floor or ceiling effects; Cronbach's α, 0.85) and an MID of 6.4 to 6.9. Vitality and health perceptions domain scores performed similarly. Respiratory symptoms domain scores improved by 7.8 points (P < .0001) and 7.5 points (P < .0001), and the physical functioning domain score improved by 4.6 points (P < .003) and 4.2 points (P = .01) at 3 and 6 months, respectively. Latent growth curve analysis confirmed a nonlinear, statistically significant improvement in respiratory symptoms and physical functioning domain scores by 3 months. INTERPRETATION: The QOL-B respiratory symptoms and physical functioning scales exhibited good psychometric properties in patients with MAC-PD. Respiratory symptoms scores improved beyond the MID by 3 months after treatment initiation. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03672630; URL: www. CLINICALTRIALS: gov.

Mycobacterium avium Pleurisy with Bronchopleural Fistula Resulting in Rapidly Progressive Respiratory Failure Diagnosed by Transbronchial Autopsy.

Nontuberculous mycobacterial lung disease usually manifests as a chronic pulmonary infection. We herein report a fatal case of Mycobacterium avium pleurisy in a man with a refractory bronchopleural fistula that led to rapidly progressive pneumonia. A post-mortem transbronchial biopsy was performed. Histopathology revealed an acute lung injury pattern and epithelioid granulomas. Variable number tandem repeat analyses and drug susceptibility testing revealed Mycobacterium avium had acquired macrolide resistance during chemotherapy with rifampicin, ethambutol, and clarithromycin. Clinicians should be aware that Mycobacterium avium pleurisy with bronchopleural fistula can lead to fatal pneumonia, especially in patients with persistently positive cultures despite multidrug treatment.

A case report: Infection-related glomerulonephritis and mantle cell lymphoma due to mycobacterium avium complex infection.

RATIONALE: Mycobacterium avium complex (MAC) infection is common in lung, liver and skin. However, MAC presenting with peritonitis is uncommon and is particularly rare in immunocompetent patients. We report a case of infection-associated glomerulonephritis and mantle cell lymphoma caused by peritonitis due to MAC. PATIENT CONCERNS: We report a case of a 73-year-old elderly man with fever and abdominal pain for 2 days and gradually developed anuria, ascites, and abdominal lymphadenopathy. DIAGNOSES: The initial diagnosis was peritonitis and acute renal failure. There was no significant relief of symptoms after empirical anti-infective therapy and hemodialysis. infection-associated glomerulonephritis, mantle cell lymphoma, and peritonitis due to MAC were diagnosed by renal biopsy, abdominal lymph node biopsy, and metagenomics next-generation sequencing. INTERVENTIONS: The patient received empirical antibiotic therapy, hemodialysis, and anti-MAC therapy. OUTCOMES: Unfortunately, the patient eventually died of septic shock after the 21st day of admissiom. LESSONS: Early diagnosis of MAC infection is essential. When the cause of fever is unknown, metagenomics next-generation sequencing can be considered.

Modulating macrophage function to reinforce host innate resistance against Mycobacterium avium complex infection.

Mycobacterium avium complex (MAC) is the main causative agent of infectious diseases in humans among nontuberculous mycobacteria (NTM) that are ubiquitous organisms found in environmental media such as soil as well as in domestic and natural waters. MAC is a primary causative agent of NTM-lung disease that threaten immunocompromised or structural lung disease patients. The incidence and the prevalence of M. tuberculosis infection have been reduced, while MAC infections and mortality rates have increased, making it a cause of global health concern. The emergence of drug resistance and the side effects of long-term drug use have led to a poor outcome of treatment regimens against MAC infections. Therefore, the development of host-directed therapy (HDT) has recently gained interest, aiming to accelerate mycobacterial clearance and reversing lung damage by employing the immune system using a novel adjuvant strategy to improve the clinical outcome of MAC infection. Therefore, in this review, we discuss the innate immune responses that contribute to MAC infection focusing on macrophages, chief innate immune cells, and host susceptibility factors in patients. We also discuss potential HDTs that can act on the signaling pathway of macrophages, thereby contributing to antimycobacterial activity as a part of the innate immune response during MAC infection. Furthermore, this review provides new insights into MAC infection control that modulates and enhances macrophage function, promoting host antimicrobial activity in response to potential HDTs and thus presenting a deeper understanding of the interactions between macrophages and MACs during infection.

Treatment Outcomes of Cavitary Nodular Bronchiectatic-Type Mycobacterium avium Complex Pulmonary Disease.

We investigated the treatment outcomes of patients with cavitary nodular bronchiectatic (C-NB)-type Mycobacterium avium complex (MAC) pulmonary disease (PD) via outcome comparisons between the fibrocavitary (FC) and C-NB types treated with guideline-based therapy (GBT) composed of daily three-drug oral antibiotics and injectable aminoglycoside. Additionally, we analyzed whether treatment with oral antibiotics alone would result in acceptable outcomes for the C-NB type. From 2002 to 2019, patients with cavitary MAC-PD who received three-drug oral antibiotics with or without an injectable aminoglycoside for ≥1 year were retrospectively enrolled at a tertiary referral center in South Korea. We compared the rates of culture conversion at 12 months according to the radiological type and treatment regimen. The overall culture conversion rate at 12 months of 154 patients with cavitary MAC-PD who received GBT was 75.3%. Among them, the culture conversion rates of 114 patients with the C-NB type were higher than that of 40 patients with the FC-type (80.7% versus 60.0%, respectively; P = 0.009). Of 166 patients with the C-NB-type treated with oral medications with or without an injectable drug, 83.7% achieved culture conversion at 12 months. The conversion rates of those who received oral medications alone and those treated with oral medications and an injectable aminoglycoside were similar (90.4% versus 80.7%, respectively; P = 0.117). In conclusion, the culture conversion rates of the patients with C-NB type treated with GBT were significantly higher than those of patients with the FC type. Additionally, the C-NB type could be treated with oral medications alone.

Disseminated Mycolicibacter arupensis and Mycobacterium avium co-infection in a patient with anti-interferon-γ neutralizing autoantibody-associated immunodeficiency syndrome.

BACKGROUND: Disseminated infections of Mycolicibacter arupensis, a slowly growing nontuberculous mycobacteria (NTM) which causes synovitis, osteomyelitis, or pulmonary infections have rarely been reported. We report a case of disseminated M. arupensis and Mycobacterium avium co-infection in a patient with anti-interferon (IFN)-γ neutralizing autoantibody-associated immunodeficiency syndrome. CASE PRESENTATION: A 68-year-old Japanese male without human immunodeficiency virus infection was referred with complaints of persistent low-grade fever, arthralgia of the upper limbs, and weight loss of 10 kg. Cervical and mediastinal lymphadenopathies as well as a nodular opacity in the right lung were detected, and biopsy specimens of the cervical lymph node yielded M. arupensis without evidence of malignant cells. M. arupensis was also detected in sputum and peripheral blood. Computed tomography (CT) revealed deterioration of the right supraclavicular lymphadenopathy with internal necrosis and multiple low-density splenic lesions. Bone marrow and aspirates from the cervical lymph node collected at initiation of treatment yielded M. avium. The presence of anti-IFN-γ neutralizing autoantibodies was detected, leading to a diagnosis of co-infection of M. arupensis and M. avium with anti-IFN-γ neutralizing autoantibody-associated immunodeficiency syndrome. Post initiation of treatment with clarithromycin, ethambutol, and rifabutin, his fever declined, and his polyarthritis resolved. He developed disseminated varicella zoster during treatment; however, a follow-up CT scan six months after treatment revealed improvement of the lymphadenopathies, consolidation in the right lung, and splenic lesions. CONCLUSION: This is the first report of disseminated M. arupensis and M. avium co-infection in a patient with anti-IFN-γ neutralizing autoantibody-associated immunodeficiency syndrome.

Impact of chronic co-infection in pulmonary Mycobacterium avium complex disease after treatment initiation.

BACKGROUND: The impact of co-infection with other pathogenic microorganisms after initiation of treatment for Mycobacterium avium complex pulmonary disease (MAC-PD) has not been clearly described. This study sought to clarify the clinical outcomes of co-infection with MAC after antimycobacterial therapy for MAC. METHODS: Co-infection status was defined as the detection of pathogenic microorganisms other than MAC in at least two consecutive sputum cultures 6-24 months after initiation of treatment. Chest computed tomography (CT) findings and culture results were compared between co-infection and MAC alone groups. RESULTS: The co-infection and MAC alone groups comprised 12 and 36 patients, respectively. The proportion of patients with sputum culture positive for MAC after 24 months of therapy did not differ significantly between the two groups [25% (3/12) vs. 16.7% (6/36); p = 0.671]. The proportion of patients with improved chest CT score after 24 months of starting treatment compared to baseline was significantly lower for the co-infection group than for the MAC alone group [16.7% (2/12) vs. 79.4% (27/34); p < 0.001]. In the co-infection group, median CT score values at 12 and 24 months did not differ from baseline. However, the MAC alone group showed significant improvement at 12 and 24 months compared with baseline. CONCLUSIONS: In the patient group with co-infection of other pathogenic microorganisms after treatment initiation for MAC there was no impact on therapeutic efficacy compared to the MAC alone group. However, therapeutic intervention interfered with improvement in chest CT findings such as nodule formation, bronchiectasis, infiltration, and cavitary lesions.

Nontubercular mycobacterial cough.

SummaryHabitual cough suppression leading to non-tuberculous mycobacteria infections and bronchiectasis has been reported. We present a case of a 55-year-old woman with a chronic history of cough with mild expectoration and frequent lower respiratory tract infections, remitting with antibiotic therapy and other supportive measures. She also reported habitual cough suppression for several years. She was eventually diagnosed with Mycobacterium avium complex (MAC) positive right middle lobe bronchiectasis-Lady Windermere syndrome and obstructive sleep apnoea (OSA), causing disabling symptoms limiting her daily activities. We aim to highlight two key issues-diagnosing MAC infections in a tuberculosis endemic country, and OSA and its long-term clinical implications.