Hot tub-related Mycobacterium avium intracellulare pneumonitis.

Atypical Mycobacteria have been widely known to cause opportunistic infections in patients with AIDS. Recently, cases have been reported of patients colonized with atypical Mycobacteria who are only partially responsive to antibacterial treatment. It is thought that perhaps these cases represent a clinically different subset of patients that not only have underlying infection, but hypersensitivity disease as well, which may be responsive to concomitant treatment with oral corticosteroids.     

Pathological findings of bronchiectases caused by Mycobacterium avium intracellulare complex

It has been argued whether bronchiectasis is truly caused by MAC infection or just a predisposed condition in which MAC colonizes. Our present study was designed to evaluate the pathological findings of bronchiectases caused by Mycobacterium avium intracellulare complex (MAC) lung infection and to demonstrate MAC in the lesion of bronchiectases. A retrospective study was performed in nine cases with positive cultures for MAC in whom lung resections were performed. A determination of whether or not MAC caused pulmonary disease was made using the 1997 criteria required by the American Thoracic Society. In addition, MAC were cultured from all nine lung specimens. Pathological findings of bronchiectases were evaluated in these nine patients. Destruction of bronchial cartilage and smooth muscles layer, obstruction of airway by granulomas, and ulceration of bronchial mucosa were frequently observed. Our present study demonstrates that destruction of fundamental bronchial structure due to extensive granuloma formation throughout the airways was likely the main cause of bronchiectases in MAC infection.     

Enzymatic profile of Mycobacterium avium and Mycobacterium intracellulare

The characterization of extracellular enzymatic activities of Mycobacterium avium and Mycobacterium intracellulare which were identified by DNA probe (Gen-Probe, Cal., USA) was carried out using the API ZYM system (API, La Balme Les Grottes, France). The enzymatic activities of M. avium were attributed to esterase (C4), esterase lipase (C8), leucin arylamidase, acid phosphatase and phosphoamidase. Enzymatic characterization of M. intracellulare was very similar to that of M. avium. However, M. intracellulare differed from M. avium in the following two points: (i) Alkaline phosphatase activity was demonstrated, (ii) Acid phosphatase activity was much stronger.     

Pathological analysis of the cavitary wall in Mycobacterium avium intracellulare complex pulmonary infection

OBJECTIVE: The present study was designed to evaluate the process of cavity formation in Mycobacterium avium intracellulare complex (MAC) lung infection, pathologically and clinically. METHODS: Using resected lung specimens, we first evaluated the distribution of MAC as well as the distribution of myofibroblasts in MAC lung infection according to several pathological findings classified as bronchiectasis, centrilobular nodules, cavity, nodules, bronchiolitis, or consolidation. Resected lung specimens (9 cases) were evaluated by special staining: Ziehl-Neelsen's method and immunohistochemically for CD68 (stain for monocytes and macrophages) and alpha-smooth muscle actin (stain for myofibroblasts). Chest CT findings were also examined in these 9 patients. In addition, the serial chest CT scans were reviewed in another 3 patients to evaluate the process of cavity formation, radiologically. RESULTS: Although extensive granuloma formations were observed in every pathological classification, MAC was demonstrated only in the necrotic tissue of the inner surface of the cavitary wall, which was connected to the airway. Myofibroblasts which expressed alpha-smooth muscle actin were intensely demonstrated in the cavitary wall compared with other pathological classifications. In the cavitary wall, the layer of epithelioid cells and multinucleated giant cells surrounded necrosis, and the layer of myofibroblasts surrounded the layer of epithelioid cells. Chest CT findings demonstrated that the cavitary walls were relatively thick. The evaluation of serial chest CT scans demonstrated that cavities were formed from previously existing nodules. CONCLUSIONS: Detection of mycobacteria in the cavitary wall, massive infiltration of myofibroblasts compared with other pathological classifications, and connection to the drainage bronchus, were believed to be important in the process of cavity formation in MAC pulmonary infection.     

Pathological and radiological changes in resected lung specimens in Mycobacterium avium intracellulare complex disease.

The present study was designed to evaluate the pathological and immunohistochemical findings of Mycobacterium avium intracellulare complex (MAC) lung infection. A retrospective study was performed in five cases with positive cultures for MAC in whom lung resections were performed between January 1989 and December 1996. A determination of whether or not MAC caused pulmonary disease was made using the 1997 criteria defined by the American Thoracic Society. In addition, MAC was cultured from all of the five lung specimens. Pathological and immunohistochemical findings as well as chest computed tomography (CT) findings were evaluated in these five patients. Pathological findings of bronchiectasis, bronchiolitis, centrilobular lesion, consolidation, cavity wall and nodules were demonstrated, respectively, in relation to chest CT findings. Extensive granuloma formation throughout the airways was clearly demonstrated. Immunohistochemical staining demonstrated: 1) epithelioid cells and giant cells; 2) myofibroblasts extensively infiltrating the cavity wall; and 3) B-cells detected in aggregates in the vicinity of the epithelioid granulomas. This study identified pathological and immunohistochemical characteristics of Mycobacterium avium complex infection relative to chest computed tomography findings and allowed the conclusion that bronchiectasis and bronchiolitis were definitely caused by Mycobacterium avium complex infection.     

Identification of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium tuberculosis complex by Gen-Probe Rapid Diagnostic System

DNA probe testing for Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium tuberculosis complex (MTC) was performed using Gen-Probe Rapid Diagnostic System (Gen-Probe Inc., San Diego, Calif., U.S.A.). By DNA probe test carried out blindfold for 48 mycobacterial strains with code numbers obtained from Kyoto University (Prof. F. Kuze), 13, 7, and 5 strains were identified as to be M. avium, M. intracellulare, and MTC, respectively. The diagnostic specificity and sensitivity of this testing were 100%. In this experiment, % hybridization of M. avium complex (MAC) and MTC were 25-55% and 45-52%, respectively. DNA probe test for 54 MTC strains including M. tuberculosis, M. bovis, M. africanum and M. microti revealed that 53 strains, except for one strain donated as a niacin-negative M. tuberculosis, reacted with MTC probe but not with MAC-probes. The one exceptional strain reacted with both the MTC- and M. avium-probes. However, when ten colonies randomly isolated from this strain on 7H11 agar plate were subjected to the DNA probe test again, all of these colonies reacted with M. avium probe, but not with MTC probe. Moreover, one representative colony was found to have alpha-antigen specific for the MAC.     

鸟-胞内分枝杆菌复合群鸟和胞内分枝杆菌亚种对20种药物的敏感性特征及亚种间药物敏感性比较

目的分析鸟-胞内分枝杆菌复合群鸟分枝杆菌亚种和胞内分枝杆菌亚种对20种药物的敏感性特征及比较2个亚种间的药物敏感性差异。方法用微孔板Alamar blue显色法分别检测97株鸟分枝杆菌和172株胞内分枝杆菌对克拉霉素、卷曲霉素和利福布丁等20种药物的最小抑菌浓度,判断其敏感性,分析2个亚种菌株对20种药物的敏感性特征以及对利福霉素类、氨基糖苷类和大环内酯类内药物的交叉耐药性,并比较2个亚种对20种药物的敏感性差异。结果对鸟分枝杆菌敏感率高于80%的药物依次是卷曲霉素(100%,97/97)、阿米卡星(97.9%,95/97)、利福布丁(96.9%,94/97)、利福平和卡那霉素(83.5%,81/97)及克拉霉素(82.5%,80/97);对胞内分枝杆菌敏感率高于80%的药物依次是阿米卡星(99.4%,171/172)、卡那霉素(95.9%,165/172)、利福布丁(95.4%,164/172)、克拉霉素(94.2%,162/172)、氯法齐明(87.2%,150/172)、卷曲霉素和罗红霉素(86.1%,148/172)及利福喷丁(82.6%,142/172)。97株鸟分枝杆菌分别...     

Comparison of prognosis of pulmonary diseases caused by Mycobacterium avium and by Mycobacterium intracellulare.

A total of 55 patients with pulmonary disease caused by Mycobacterium avium and by Mycobacterium intracellulare were compared for their prognosis. Causative mycobacteria were identified by the DNA probes (Gen-Probe) method. Of the 55 patients, 28 had pulmonary disease caused by M avium and the remaining 27, by M intracellulare. Of the former group, four patients had progressive disease, and three of them died during the observation period. In contrast, only one of the latter group had progressive disease. On the other hand, only one of the former group was cured. In contrast, six of the latter group were cured, showing the closure of cavity and the disappearance of mycobacteria from the sputum. The prognosis of pulmonary disease caused by M avium appears to be worse than that caused by M intracellulare.     

In vitro susceptibilities of Mycobacterium avium and Mycobacterium intracellulare to various drugs

Mycobacterium avium and M. intracellulare isolated from patients infected with M. avium complex (MAC), which were identified by Gen-Probe Rapid Diagnostic System for the MAC, were studied for susceptibility to various antimicrobial agents, including rifampicin, rifabutin, kanamycin, streptomycin, amikacin, ethambutol, clofazimine, isoniazid, ofloxacin, ciprofloxacin and cycloserine. Ratio of resistant strains to test strains to a given agent at prescribed concentration in cases of M. avium and M. intracellulare was compared with each other. Test strains of M. avium were more resistant to rifampicin, rifabutin, kanamycin, streptomycin, amikacin, ethambutol and clofazimine than test strains of M. intracellulare. Conversely, the M. avium strains were more susceptible to ofloxacin, ciprofloxacin and cycloserine than M. intracellulare strains. The difference in the drug susceptibility between M. avium and M. intracellulare was statistically significant by chi 2-test (P less than 0.005-0.05). There was no statistically significant difference between the two MAC species with respect to the susceptibility to isoniazid.     

Polymerase chain reaction for the differentiation of Mycobacterium intracellulare and Mycobacterium avium

Polymerase chain reaction (PCR) amplification was performed using DNA purified from 15 mycobacterial type strains and from 21 specimens isolated from patients suspected to have non-tuberculous mycobacterial diseases. Using a primer set of MTB1-MTB2,11 specimens out of 21 were Mycobacterium avium and 8 were M. intracellulare, which were verified by the Gen Probe Rapid Diagnostic System for the M. avium complex (MAC). One of the remaining 2 specimens which did not hybridize with the probe for the MAC was identified as M. kansasii and the other was not specifically identified by the conventional culture method. PCR amplification, using a primer set of TB1-TB3, was also performed for the specific identification of M. tuberculosis complex.     

Use of DNA probes to detect Mycobacterium intracellulare and "X" mycobacteria among clinical isolates of Mycobacterium avium complex.

A mycobacterial DNA probe (designated X) was recently developed to help identify Mycobacterium avium complex (MAC) isolates that are nonreactive with probes specific for M. avium or Mycobacterium intracellulare. The prevalence of X probe-positive mycobacteria in clinical specimens and their role in causing disease is unknown. Using a DNA probe kit that includes the X probe, we characterized 100 consecutive clinical MAC isolates as M. avium, M. intracellulare, or X. Lysates from 81 of the isolates reacted with the M. avium probe, 13 with the M. intracellulare probe, 3 with the X probe, and 3 failed to hybridize with any of the probes. All three X-positive isolates were recovered from sputa of patients who were recent immigrants to the United States and who presented with hemoptysis. One isolate was from a Hispanic man infected with human immunodeficiency virus type 1 (HIV-1) and the other 2 were from Filipino patients with no HIV-1 risk factors. This study also showed a higher than expected number of M. intracellulare isolates from blood and cerebrospinal fluid of HIV-1-infected patients.     

Mycobacterium avium complex pleuritis

Non-tuberculous mycobacterium infection is rarely accompanied by pleural involvement. We report a very rare case of Mycobacterium avium-intracellurare complex (MAC) pleuritis with massive pleural effusion. The patient was a non-compromised 67-year-old female and had been treated for pulmonary non-tuberculous mycobacterium infection. She was admitted to hospital because of general malaise, low-grade fever and right pleural effusion. Cytological examination of the effusion did not show malignant cells. MAC was only identified by culture and PCR. No other bacteria were detected. Complete resolution of the pleural effusion occurred after administration of anti-tubercular agents (isoniazid, rifampin, ethambutol) and clarithromycin.