Non-tuberculous mycobacteria in patients with bronchiectasis

BACKGROUND

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms. Patients with pre-existing lung damage are susceptible to NTM, but their prevalence in bronchiectasis is unknown. Distinguishing between lung colonisation and disease can be difficult.

METHODS

A prospective study of 100 patients with bronchiectasis was undertaken to evaluate the prevalence of NTM in sputum, and a retrospective analysis of clinical, microbiological, lung function and radiology data of our clinic patients with NTM sputum isolates over 11 years was performed.

RESULTS

The prevalence of NTM in this population of patients with bronchiectasis was 2%. Patients in the retrospective study were divided into three groups: bronchiectasis+multiple NTM isolates (n=25), bronchiectasis+single isolates (n=23), and non-bronchiectasis+multiple isolates (n=22). Mycobacterium avium complex (MAC) species predominated in patients with bronchiectasis compared with non-bronchiectasis lung disease (72% v 9%, p<0.0001). Single isolates were also frequently MAC (45.5%). Multiple isolates in bronchiectasis were more often smear positive on first sample than single isolates (p<0.0001). NTM were identified on routine screening samples or because of suggestive radiology. No particular bronchiectasis aetiology was associated with an NTM. Pseudomonas aeruginosa and Staphylococcus aureus were frequently co-cultured. Six (25%) of multiple NTM patients had cavities of which five were due to MAC. Half the patients with multiple isolates were treated, mostly due to progressive radiology.

CONCLUSIONS

NTM are uncommon in non-cystic fibrosis bronchiectasis. Routine screening identifies otherwise unsuspected patients. MAC is the most frequent NTM isolated.

[Video assisted thoracic surgery for Mycobacterium avium complex pulmonary disease spread over multiple pulmonary lobe within one lung]

A 75-year-old woman with Mycobacterium avium complex (MAC) pulmonary disease who had been treated by drug therapy for 7 years was admitted on an emergency basis for hemoptysis. Through the previous 7 years, her sputum cultures had been positive for MAC, and her clinical symptoms and examinations, such as chest X-ray and computed tomography, revealed that her condition had worsened. The lesions spread over the right middle lobe, segment 3 (S3) in the right upper lobe, and segment 6 (S6) in the right lower lobe, however, no lesions were present in the left lung. Since we believed that the disease was localized unilaterally, surgical treatment was selected. The surgical procedures that were employed included right middle lobectomy, right S3 segmentectomy and partial resection of right S6 by thoracoscopy. Sixteen months postoperatively, the sputum culture is negative for MAC. Our procedure enabled the preservation of effective lung function and was successful in controlling MAC pulmonary disease. It is believed that surgery for MAC pulmonary disease should be evaluated in more patients to decide the appropriate surgical indication and procedure.

Thin-section CT findings of nontuberculous mycobacterial pulmonary diseases: comparison between Mycobacterium avium-intracellulare complex and Mycobacterium abscessus infection

We aimed to compare the CT findings of nontuberculous mycobacterial pulmonary diseases caused by Mycobacterium avium-intracellulare complex (MAC) and Mycobacterium abscessus. Two chest radiologists analyzed retrospectively the thin-section CT findings of 51 patients with MAC and 36 with M. abscessus infection in terms of patterns and forms of lung lesions. No significant difference was found between MAC and M. abscessus infection in the presence of small nodules, tree-in-bud pattern, and bronchiectasis. However, lobar volume decrease (p=0.001), nodule (p=0.018), airspace consolidation (p=0.047) and thin-walled cavity (p=0.009) were more frequently observed in MAC infection. The upper lobe cavitary form was more frequent in the MAC (19 of 51 patients, 37%) group than M. abscessus (5 of 36, 14%) (p=0.029), whereas the nodular bronchiectatic form was more frequent in the M. abscessus group ([29 of 36, 81%] vs. [27 of 51, 53%] in MAC) (p=0.012). In conclusion, there is considerable overlap in common CT findings of MAC and M. abscessus pulmonary infection; however, lobar volume loss, nodule, airspace consolidation, and thin-walled cavity are more frequently seen in MAC than M. abscessus infection.

Clinical and prognostic importance of serotyping Mycobacterium avium-Mycobacterium intracellulare complex isolates in human immunodeficiency virus-negative patients

We studied whether the serotypes of Mycobacterium avium-Mycobacterium intracellulare complex (MAC) isolates determine the prognosis for pulmonary MAC disease. We prospectively monitored a cohort of 68 patients with pulmonary MAC disease for whom the serotype-specific glycopeptidolipids in isolates were identified using thin-layer chromatography and fast atom bombardment mass-spectrometry in 1990 and 1995. Serovar 4 Mycobacterium avium was detected in 40/68 patients (58.8%). Other serotypes were serotypes 1 (five cases), 6 (three cases), 8 (seven cases), 9 (three cases), 14 (four cases), and 16 (six cases). Patients with serovar 4 were significantly (P < 0.01) younger (63.0 +/- 9.8 years) than patients with other serotypes (71.8 +/- 10.3). Patients who failed treatment had a significantly poorer prognosis than other patients. There were no cases of MAC-related death in the cured group. Chest radiographic findings progressively worsened in 36 (90%) of patients with serotype 4, and 14/36 died from respiratory failure caused by pulmonary Mycobacterium avium disease. The patients with serotype 4 had a significantly poorer prognosis than patients with other serotypes. These results show that both the outcome of chemotherapy and the serotypes of MAC isolates are important for assessing the prognosis of pulmonary MAC disease.

[A case of pulmonary mycobacterium intracellulare infection complicated with pneumothorax and pleurisy]

A 74 year-old female complaining of increased cough and sputum was admitted to our hospital on June 14th 2004. She had been diagnosed as Mycobacterium intracellulare (M. intracellurare) infection since 2002 and had been treated from March to October 2003 in the Department of General Medicine in our hospital. Chest CT on admission showed diffuse small nodular shadows in the lung, a cavity, pneumothorax, and pleural effusion in the right lung. The sputum smear was positive for acid-fast bacilli and sputum PCR examination was positive for M. intracellulare. She was diagnosed as the recurrence of non-tuberculous mycobacterium (NTM) infection and treatment of NTM infection was started. No other infections were suspected and the pneumothorax and pleural effusion gradually improved with the treatment. We concluded that the pneumothorax and pleural effusion were caused by NTM infection. Since pneumothorax is an extremely rare complication in NTM infections we thought it is worth-while to report our case.

Septic arthritis and granulomatous synovitis caused by infection with Mycobacterium avium complex in a horse

A 12-year-old American Saddlebred gelding was referred to a veterinary teaching hospital for evaluation of a chronic lameness problem in the right radiocarpal joint. The horse had been treated for osteoarthritis of the right radiocarpal joint with multiple injections of cortisone during the past 3 years. The horse was severely lame on the right forelimb at a trot. Radiography and computed tomography revealed a 3 x 2-cm lytic defect in the distal portion of the radius and periarticular bone proliferation around the right radiocarpal joint. Ultrasonography of the distal portion of the radius revealed a soft tissue mass in the palmarolateral aspect of the joint. Proliferative synovium with a large amount of fibrin was observed in the dorsal and palmar aspects of the joint via arthroscopic examination of the right radiocarpal joint. Histologic examination of synovial biopsy specimens revealed proliferative granulomatous synovitis with giant cells. Mycobacterium avium complex was cultured from the synovial fluid. Infection with M avium complex should be considered in horses with chronic recurring arthritis associated with granulomatous synovitis.

[Thoracoscopic resection for Mycobacterium avium complex]

We report 2 cases of thoracoscopic resection for patients with Mycobacterium avium complex (MAC). A 25-year-old female was referred to our hospital because of abnormal shadows in the right lower lung field on chest X-ray. Her chest computed tomography (CT) showed that the lesion was localized in the right lower lobe. She was given a diagnosis of MAC by polymerase chain reaction (PCR) of sputum. Thoracoscopic lobectomy was performed after chemotherapy for 10 months. A 64-year-old female was referred to our hospital because of hemoptysis. Bronchiectasis had been diagnosed in her since the age of 35 years, and then she was given a diagnosis of secondary MAC. Her chest CT showed bronchiectasis, and consolidations were localized in the superior segment of the right lower lobe. Then superior segmentectomy of the right lower lobe under video-assisted thoracoscopic surgery (VATS) was performed. It was reported that surgical intervention is indicated in patients with MAC, when persistent hemoptysis is seen or chemotherapy is ineffective. If the lesion is localized, lung resection under VATS may be a good option in selected patients.

Hypothesis on the Evolution of Cavitary Lesions in Nontuberculous Mycobacterial Pulmonary Infection: Thin-Section CT and Histopathologic Correlation

OBJECTIVE

The objectives of our study were to evaluate the thin-section CT findings of the cavitary form of nontuberculous mycobacterial pulmonary infection and correlate these imaging findings with the histopathologic findings concerning the development of bronchiectasis and of centrilobular nodules and cavitary lesions.

MATERIALS AND METHODS

We retrospectively reviewed thin-section CT scans (2.5-mm collimation, both axial and coronal reformation images) of 24 cases (male-female ratio, 13:11; mean age, 61 years; age range, 43-82 years) of the cavitary form of culture-proven Mycobacterium avium-intracellulare complex pulmonary infection including two cases with lobectomy specimens. Any changes in CT findings detected on the follow-up CT scans that were available for seven patients (follow-up interval, 6-24 months; mean, 12 months) were also assessed.

RESULTS

Thin-section CT findings were bronchiectasis (24/24 patients, 100%), a patent bronchus running into a cavitary lesion (the "feeding bronchus" appearance) (18/24, 75%), nodules less than 10 mm (17/24, 71%), centrilobular nodules (17/24, 71%), nodules of 10-30 mm (13/24, 54%), peribronchial nodules (8/24, 33%), lobular consolidation (6/24, 25%), bronchial wall thickening (4/24, 17%), and consolidation (2/24, 8%). Two lobectomy specimens showed large cavitary consolidations with the feeding bronchus appearance on pathologic specimens. In two patients, small peribronchial nodules had changed into cavitary nodules with the feeding bronchus appearance on follow-up CT, which represented inflamed focal cystic bronchiectasis.

CONCLUSION

In the cavitary form of M. avium-intracellulare complex pulmonary infection, the feeding bronchus appearance is another very frequent thin-section CT finding. This appearance may suggest that peribronchial nodules of M. avium-intracellulare complex infection evolve into inflamed focal cystic bronchiectasis manifesting as cavitary lesions.

Chronic necrotizing pulmonary aspergillosis complicated by a cavitary lesion caused by Pulmonary Mycobacterium-avium complex disease

A 66-year-old woman who had undergone one year's treatment for pulmonary nontuberculous mycobacterial disease due to Mycobacterium avium (rifampicin, ethambutol, clarithromycin, streptomycin-->levofloxacin) five years earlier was admitted to our hospital because of continuous fever and a newly detected abnormal chest shadow, which was like a fungus ball in the right upper lobe on chest computed tomography in the giant cavitary lesion caused by pulmonary Mycobacterium-avium complex (MAC) disease. A diagnosis of chronic necrotizing pulmonary aspergillosis (CNPA) complicated by pulmonary MAC disease was made because Aspergillus niger was isolated from several sputum specimens, anti-aspergillus antibody was positive, and clinical symptoms such as fever, were disclosed with the radiological finding of a fungus ball-like shadow and an infiltration shadow around the cavity. The patient had received various forms of antifungal chemotherapy, but the clinical effect had been poor. Since then, she had been slowly worsening. Although mycetomas, with the typical appearance of a fungus ball on a chest radiograph, have been reported to easily form in cavitary lesions caused by previous pulmonary tuberculosis, we believe, as illustrated by the present case, that they could also form in such lesions caused by pulmonary MAC disease, since the frequency of pulmonary nontuberculous mycobacterial disease has recently been increasing in comparison with that of pulmonary tuberculosis.

[The non-tuberculous mycobacteriosis]

The Japanese Society for Tuberculosis officially announced that public name of "atypical mycobacteriosis" was changed to the Nontuberculous Mycobacteriosis, on April 2003. We sent out questionnaires on number of nontuberculous mycobacteriosis (NTM) to 2051 respiralogists. The number of newly diagnosed NTM patients from Apr. 2001 to Sep. 2001 were 1522 cases, those were 29.2% of all mycobacteriosis containing TB. The M. avium-intracellulare (MAC) disease took up 82.8% of all NTM, and M. kansasii disease took 8.1%. The rare species were M. gordonae, M. abscessus, M. fortuitum, M. chelonae, M. szulgai, M. scrofulaceum and M. xenopi. The former investigations noted that in the northan half of Japan, M. avium disease predominated M. intracellulare disease in MAC, and M. intracellulare disease overwhelmed in the southern half of Japan. Our newest examination revealed that in the northan half, M. avium is predominant but, in the southern half, the rate of two species is almost the same. Dr. Kobashi and his group surveyed the effect of combined chemotherapy following the guidelines on treatment for MAC disease. They revealed that the clinical effect of the combined chemotherapy (RFP, EB, SM and CAM) was better than that of the other regimens. However the efficacy of this therapy was unsatisfactory compared with the effect for pulmonary TB.

Infected bronchogenic cyst due to Mycobacterium avium in an immunocompetent patient

We present a patient with intermittent pain over the right chest for 2 years. Computed tomograph of the chest disclosed a cystic tumor over the right posterior basal lung. Pathological examinations of the excised tumor disclosed a granulomatous inflammation within the multilocular bronchogenic cysts and microbiological culture of the tissue yielded Mycobacterium avium. This is the first reported case of infected bronchogenic cyst caused by M. avium in humans.

[Intense 18F-fluorodeoxyglucose uptake caused by pulmonary Mycobacterium intracellulare infection]

A 70-year-old woman was admitted to our hospital for the evaluation of a pulmonary nodule in the left S5 segment. On 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET), the nodule showed substantial uptake of 18F-fluorodeoxyglucose. Bronchoscopy was performed, but the cytology was negative. For a pathological diagnosis, a lung biopsy was carried out using video-associated thoracoscopy. The biopsy specimen showed granuloma formation with multinuclear giant cells. An acid-fast bacteria culture of the specimen was positive for Mycobacterium intracellulare. An atypical mycobacterium infection should be considered as a possibility when the 18FDG-PET of patients with pulmonary nodules is interpreted.

[Prevalence of mycobacteriosis and tuberculosis in a reference hospital, Cordoba province]

Environmental mycobacteria (EM) constitute an important group of bacteria species found in the environment. They can colonize and occasionally produce disease in man. Sixteen thousand three hundred samples from 9300 adult symptomatic patients from the Hospital Regional of Tuberculosis in Cordoba were bacteriolocally investigated. The isolations were performed by culture on Lowenstein Jensen and Stonebrink culture media. The colonies of acid fast bacilli (AFB) were identified by biochemical and molecular tests. Among 716 culture positive cases, 684 (95.5%) were due to Mycobacterium tuberculosis complex and 32 to environmental mycobacteria. Serial samples allowed the confirmation of the etiological agent in culture and correlated with consistent clinical and radiological abnormalities. Seventy-five percent of these patients were affected by M. avium complex, 15.6% by M. fortuitum, 3.1% Mycobacterium kansasii and 6.3% Mycobacterium chelonae. Among tuberculosis cases, 94.5% and 5.5% had pulmonary and extrapulmonary disease respectively.

[A case of pulmonary Mycobacterium intracellulare infectious disease with a solitary pulmonary nodule in the peripheral lung field]

A 63-year-old woman was admitted to our hospital because of a solitary nodule (20 x 20 mm) in the right S3 which was first detected during a health examination. Because radiological findings for the nodule, such as pleural indentation and spicula on chest CT led us to suspect a pulmonary adenocarcinoma, we could not completely rule out lung cancer and performed a bronchoscopic examination on the third day after admission. However, no definite diagnosis could be made. Therefore, video-assisted thoracic surgery (VATS) was performed, and a caseating epitheloid granuloma with acid-fast bacilli was found. Initially, we administered antituberculous drugs for pulmonary tuberculoma, but then changed to combined chemotherapy using RFP, EB, CAM and SM after identification of Mycobacterium intracellulare by a culture test of resected tissue. We report a rare case with a solitary nodule caused by pulmonary Mycobacterium intracellulare infectious disease which is indicative of lung cancer.

Clinical features of eleven cases of Mycobacterium avium-intracellulare complex pulmonary disease associated with pneumoconiosis

The relationship between silicosis and tuberculosis is well known. Also other mycobacteria such as Mycobacterium kansasii often occur in association with pneumoconiosis. However, there are few reports describing an association of M. avium-intracellulare complex (MAC) lung disease and pneumoconiosis. The purpose of the present study is to describe clinical features of MAC respiratory infection associated with pneumoconiosis. Eleven patients with MAC respiratory infection associated with pneumoconiosis (all men, 6 with silicosis and 5 with welders' pneumoconiosis) were collected. A determination of whether or not MAC caused pulmonary disease was made using the 1997 criteria required by the American Thoracic Society. Radiologically, cavity formation as well as upper lung field predominance of MAC disease were observed in 8 of 11 cases (72.7%). Two of 11 patients died of respiratory failure. Our present study clearly demonstrates that clinical features of MAC respiratory infection associated with pneumoconiosis were different from MAC without underlying diseases.

AIDS-related ankle arthropathy: mycobacterium avium-intracellulare infection

We present a case of Mycobacterium avium-intracellulare (MAI) infection of the ankle joint in a patient with HIV infection. The patient presented with a painful, destructive arthropathy of the ankle. Initial microbiological studies were negative but infection with MAI was later identified from biopsies taken during hindfoot fusion. Antibiotic triple therapy was given and the patient remains pain-free without evidence of active infection. To our knowledge, this is the first case of MAI infection of the ankle reported in the literature. A high index of suspicion of (atypical) Mycobacterial infection should be maintained in patients with HIV infection presenting with an indolent but destructive arthropathy of the ankle joint.

[Diagnosis of disseminated mycobacterial infection in AIDS patients by US-guided fine needle aspiration biopsy of lymphnodes and spleen]

Our aim was to evaluate the efficacy of abdominal US and fine-needle aspiration biopsy (FNAB) in the diagnosis of disseminated mycobacteriosis (DM) in patients with Acquired Immunodeficiency Syndrome (AIDS). We reviewed the US and clinical records of 18 AIDS patients (12 males; 22-43 years) with DM studied with abdominal US. 18 patients underwent fine-needle aspiration biopsy of enlarged abdominal lymphnodes and 11 underwent FNAB of the spleen. All aspirates were studied with acid-fast stain for fast examination and cultures for isolation of mycobacteria. Abdominal US showed: enlarged abdominal lymphnodes (diameter range: 5-35 mm; mean 17 mm) splenomegaly (spleen diameter range: 14-22 cm; mean: 16.2 cm) and hepatomegaly (right hepatic lobe thickness range: 14.5-18.5 cm) in all patients; multiple splenic abscesses (diameter range: 3-20 mm) in 11 patients; small intestine wall thickening in 5 patients (maximum bowel wall thickness range: 7-15 mm); mild to moderate ascites in 8 patients; pleural effusion in 4 patients; hyperechogenicity of the kidney cortex in 5 patients; peritoneal abscesses in one and a retroperitoneal abscess in one patient. fast-acid-stain of spleen and/or lymphnode FNAB specimens allowed early diagnosis of mycobateriosis in 18/18 cases (100%). Cultures of lymphnode aspirates grew mycobacteria in 10/18 patients (56%). Spleen aspirates grew mycobacteria in 11/11 patients (100%) Blood cultures were positive in 6/18 patients (33%). Diagnosis of species was M. tuberculosis in 9 and M. avium in 6 patients. In 3/18 patients (17%) all cultures were negative. In conclusion, abdominal US features suggest DM in AIDS patients. Spleen and/or lymphnode FNAB allows a specific diagnosis in 100% of the patients.

A patient with a Mycobacterium avium complex infection complicated by systemic lupus erythematosus

A 41-year-old woman was admitted to our hospital because of fever and polyarthralgia. A diagnosis of systemic lupus erythematosus (SLE) was made based on the findings of polyarthritis, leukocytopenia, lymphocytopenia, proteinuria, and positive reactions for antinuclear antibody (ANA) and anti-double strand (ds)DNA antibody. She had also been suffering from a pulmonary Mycobacterium avium complex (MAC) infection with such symptoms as cough and sputum for the past 3 years. Antimicrobial drugs for MAC infection were administered first, and later she was given cyclophosphamide pulse therapy, consisting of methylprednisolone (8 mg/day) and mizoribine (100 mg/day). Owing to these therapeutic regimens, SLE was successfully treated without an exacerbation of the MAC infection. The risk factors for MAC infection and SLE are also discussed.

Treatment of Mycobacterium avium complex immune reconstitution disease in HIV-1-infected individuals

Immune reconstitution disease caused by Mycobacterium avium complex (MAC) infection presenting shortly after the introduction of highly active antiretroviral therapy (HAART) has been reported with increasing frequency in persons with HIV-1 infection during the past several years. Several therapeutic modalities have been utilized for this entity, but the optimal means of treating MAC immune reconstitution disease remains unclear. We now describe a patient who underwent some of these therapies. We then review the therapeutic outcomes from the numerous case reports of this disorder. Finally, we propose recommendations and a clinical algorithm regarding the optimal means of treatment of MAC immune reconstitution disease during HIV-1 infection.

Scintigraphic Findings of Mycobacterium avium complex Tenosynovitis of the Index Finger in a Patient With Systemic Lupus Erythematosus

The presented case is a 36-year-old woman with a history of systemic lupus erythematosus for 10 years. She had progressively painful swelling of the right index finger that later proved to be a rare case of tenosynovitis caused by Mycobacterium avium complex. Serial images of 3-phase bone scans, gallium scan, and magnetic resonance imaging demonstrate the area of involvement.

Disseminated mycobacterial infection in AIDS patients: abdominal US features and value of fine-needle aspiration biopsy of lymph nodes and spleen

BACKGROUND

We evaluated the efficacy of abdominal ultrasound (US) and fine-needle aspiration biopsy (FNAB) in the diagnosis of disseminated mycobacteriosis (DM) in acquired immunodeficiency syndrome (AIDS).

METHODS

Twelve AIDS patients (nine male, three female; age range, 22-43 years) with DM underwent abdominal US within 2 days after admission with 3.5- to 5-MHz convex probes and a 7.5-MHz linear probe. All patients underwent FNAB of one or two enlarged abdominal lymph nodes. Eight patients underwent FNAB of the spleen. The aspirated specimens were stained with acid fast for quick examination and cultured for isolation of mycobacteria.

RESULTS

Abdominal US showed enlarged, hypoechoic, round or oval, abdominal lymph nodes (diameter, 10-35 mm; mean, 18 mm) in all patients; splenomegaly (spleen diameter, 14-22 cm; mean, 16.8 mm) in all patients; numerous splenic abscesses (diameter, 3-20 mm) in nine patients; hepatomegaly (right hepatic lobe thickness, 14.5-17 cm) in all patients; small intestinal wall thickening in five patients (maximum bowel wall thickness, 7-15 mm); mild to moderate ascites in six patients; pleural effusion in four patients; bilateral enlargement of the kidneys with hyperechogenicity of the cortex in three patients; and a retroperitoneal tubercular abscess in one patient. No complication occurred after FNAB of lymph nodes and spleens. Fast-acid stain of spleen and/or lymph node FNAB specimens allowed early diagnosis of mycobacteriosis in 12 of 12 cases (100%). Cultures of lymph node aspirates grew mycobacteria in six of 12 patients (50%). Spleen aspirates grew mycobacteria in nine of nine patients (100%). Blood cultures were positive in four of 12 patients (33%). Mycobacterium tuberculosis was diagnosed in six patients and M. avium in five.

CONCLUSION

Abdominal US features can suggest DM in AIDS patients. Spleen and/or lymph node FNAB indicated the specific diagnosis in 100% of patients.

Uptake of fluorine-18-fluorodeoxyglucose in pulmonary Mycobacterium avium complex infection

Two patients showing abnormal fluorine-18-fluorodeoxyglucose (FDG) uptake due to Mycobacterium avium complex (MAC) infection are presented. Intense focal FDG uptake in the lung field could have been caused by an infectious disease such as MAC. This should be considered as a possibility when FDG whole-body scans of patients with pulmonary nodules are interpreted. To our knowledge, this is the first description of an FDG-positron emission tomography (FDG-PET) image of MAC infection of the lung.

[Radiological findings of non-tuberculous mycobacteria respiratory infection]

In these 15 years, the clinical importance of non-tuberculous mycobacteria respiratory infection has been increasing. Especially, from the report of Prince et al., it has been suggested that Mycobacterium avium complex (MAC) respiratory infection is increasing especially in elderly women without underlying diseases. In MAC respiratory infection, right middle lobe and left lingula are frequently involved and centrilobular nodules and diffuse bronchiectasis are characteristic radiological findings. In addition, successive evaluation of chest CT has demonstrated that grade of bronchiectasis deteriorated, suggesting that bronchiectasis is caused by MAC respiratory infection. More recently, pathological findings of MAC respiratory infection as well as the pathogenesis of MAC respiratory infection has been partially clarified.