Early IL-17A production helps establish Mycobacterium intracellulare infection in mice

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates of M. intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1–2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and late (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs of M. intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover, in vitro data showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells upon M. intracellulare infection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonary M. intracellulare infection in mice, at least in part through MMP-3 production.

To determine how nontuberculous mycobacteria (NTM) infection is established and how NTM disease progresses, we established a chronic NTM mouse model by intranasal inoculation of M. intracellulare, one of the most frequently isolated strains in NTM patients. The bacteria persistently grew in the lungs and caused fibrotic lung damage with over 50% mortality over 39 weeks. Neutrophils and IL-17A rapidly increased in the lung during early (1–2 weeks) infection, and neutrophils reappeared at 39 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and chronic (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. Neutralization of IL-17A during early (0–2 weeks) infection significantly reduced mortality, bacterial burden, fibrotic lung damage, and lung matrix metalloproteinase (MMP)-3 at 39 weeks postinfection. Exogenous IL-17A exaggerated the production of MMP-3, but not MMP-9, by lung epithelial cells upon M. intracellulare infection. This study demonstrates that early IL-17A production contributes to established M. intracellulare infection in mice.

Retrospective evaluation of natural course in mild cases of Mycobacterium avium complex pulmonary disease

Background

There is no proven management for mild cases of Mycobacterium avium complex (MAC) pulmonary disease, who do not immediately receive treatment and are managed with observation alone, because its long term-natural course, factors predictive of deterioration, and the effect of treating the disease remain unclear. Thus, we sought to investigate the natural course of mild cases of MAC pulmonary disease.

Methods

We conducted a multicenter retrospective study. Sixty-five patients with mild MAC pulmonary disease in whom treatment was withheld for at least 6 months after diagnosis were retrospectively recruited after a review of 747 medical records. Longitudinal changes in clinical features were evaluated by using a mixed effects model.

Results

Mean follow-up was 6.9 ± 5.7 years. During the follow-up period, 15 patients (23%) required treatment and 50 (77%) were managed with observation alone. At diagnosis, 65 patients had nodular bronchiectatic disease without fibrocavitary lesions. Among clinical features, mean body mass index (BMI), forced expiratory volume in 1 second as percent of forced vital capacity (%FEV₁), nodular lung lesions, and bronchiectasis worsened significantly in the observation group during follow-up. In the treatment group, BMI, and %FEV₁ were stable, but bronchiectasis significantly worsened. At diagnosis, the polyclonal MAC infection rate in the treatment group was higher than that in the observation group. Other microbiological factors, such as insertion sequences, did not differ significantly between the groups.

Conclusions

Mild MAC pulmonary disease progresses slowly but substantially without treatment. Treatment prevents the deterioration of the disease but not the progression of bronchiectasis. Polyclonal MAC infection is a predictor of disease progression.

Neutrophil predominance in bronchoalveolar lavage fluid is associated with disease severity and progression of HRCT findings in pulmonary Mycobacterium avium infection

Pulmonary Mycobacterium avium complex (MAC) infection is increasing in prevalence worldwide even in immunocompetent individuals. Despite its variable clinical course, the clinical and immunological factors associated with radiographical severity and progression are not largely unknown. We aimed to study the association between the inflammatory cell and cytokine profiles at the local infected site, and the radiological severity and/or progression of pulmonary MAC infection. In this retrospective cohort study, 22 healthy subjects and 37 consecutive patients who were diagnosed as having pulmonary MAC infection by positive cultures of bronchoalveolar lavage (BAL) fluids were enrolled. The 37 patients were divided into 2 groups based on the predominant BAL inflammatory cell type: the lymphocyte-dominant (LD) group and neutrophil-dominant (ND) groups. The high-resolution computed tomography score in both the lavaged segment and whole lung and cytokines profiles were compared between the 2 groups. The clinical course after the BAL procedure was also compared between the 2 groups. Both the segment and whole lung scores in the ND group were significantly higher than the LD group (P < 0.001). Levels of IL-8 in the BAL fluids were significantly higher in the ND group compared to the LD group (P = 0.01). In contrast, levels of IL-22 were significantly lower in the ND group compared to the LD group (P < 0.001). The prevalence of patients who showed deterioration of the disease was significantly higher in the ND group (83.3%) than the LD group (12.5%) (P < 0.01).

Neutrophil-predominant inflammatory response at the infected site is associated with the radiographical severity and progression of pulmonary MAC infection.

Natural course of the nodular bronchiectatic form of Mycobacterium Avium complex lung disease: Long-term radiologic change without treatment

BACKGROUND/PURPOSE

Although the incidence of Mycobacterium avium complex (MAC) lung disease is increasing, the long-term natural course of the nodular bronchiectatic form of MAC lung disease is not well described. The objective of our study is to evaluate long-term radiologic changes in untreated MAC lung disease by analyzing serial chest computed tomography (CT) scan findings.

METHODS

Of 104 patients with MAC lung disease, we selected 40 untreated nodular bronchiectatic MAC patients who underwent serial chest CTs without treatment for at least four years (mean = 6.23 years). Majority of patients have minimal symptoms. Two chest radiologists retrospectively reviewed initial and final chest CT scans. Each chest CT scan was scored for presence and extent of bronchiectasis, cellular bronchiolitis, consolidation, cavity, and nodule (maximum score: 30).

RESULTS

Of 40 patients, 39 (97.5%) experienced a significant increase in overall CT score (overall difference = 4.89, p<0.001). On repeated measure analysis of variance analysis, cavity yielded the largest increase compared with cellular bronchiolitis (p = 0.013), nodule (p<0.001), and consolidation (p = 0.004). However, there was no significant difference in mean score change between cavity and bronchiectasis (p = 0.073). In analysis between radiologic parameters and the absolute number of involved segments, bronchiectasis showed most significant change compared with nodule (p<0.001) and consolidation (p<0.001).

CONCLUSIONS

Most untreated nodular bronchiectatic MAC lung disease cases showed radiologic deterioration over long-term observation periods when we compared serial chest CT scans. Careful monitoring of MAC lung disease with serial chest CT scan can be beneficial in these untreated patients.

Primary cutaneous Mycobacterium avium complex infection following squamous cell carcinoma excision

Primary cutaneous Mycobacterium avium complex (MAC) infection is rare, particularly among immunocompetent patients. We present the case of a purportedly healthy patient with primary cutaneous MAC infection arising within the excision margins of multiple infiltrating squamous cell carcinomas.

Complete Remission of Minimal Change Disease Following an Improvement of Lung Mycobacterium avium Infection

A 46-year-old woman suddenly developed peripheral edema. Her massive proteinuria, hypoproteinemia, and renal biopsy findings yielded the diagnosis of minimal change disease (MCD). In addition, lung Mycobacterium avium infection was diagnosed according to a positive culture of her bronchoalveolar lavage fluid. The lung lesion was improved by anti-nontuberculous mycobacteria therapy. Surprisingly, her proteinuria also gradually decreased and she attained complete remission of MCD without any immunosuppressive therapy. She has subsequently remained in complete remission. We herein report an interesting case of MCD with lung Mycobacterium avium infection, suggesting a causal relationship among infection, immune system abnormality, and MCD/nephrotic syndrome.

Characteristics of pulmonary Mycobacterium avium complex disease diagnosed later in follow-up after negative mycobacterial study including bronchoscopy

BACKGROUND

We occasionally experience cases suspected of pulmonary Mycobacterium avium complex (MAC) disease without positive bacterial cultures.

OBJECTIVE

To evaluate features of pulmonary MAC cases diagnosed later in the follow-up after negative intensive investigation.

METHODS

We defined and compared three groups; the first study negative (FSN) group, the first study positive (FSP) group, and MAC negative group. The FSN group consisted of patients negative for MAC isolation by bronchial washing performed between 2007 and 2011, but positive later. Patients with positive MAC cultures in the first study were incorporated into the FSP group. MAC negative group consisted of MAC suspects without MAC isolation in the follow-up.

RESULTS

Twenty-four patients were classified as FSN group, 61 as MAC negative group and 265 as FSP group. FSN group exhibited more solitary nodule pattern (n = 7 in FSN, n = 6 in FSP; p < 0.001) and less nodular/bronchiectatic (NB) diseases (n = 17 in FSN, n = 245 in FSP; p < 0.001). When limited to NB type, the FSP group had more cavitations (6% in FSN, 32% in FSP; p = 0.028). Patients with more than three lung lobes involved were more frequent in the FSN group compared with FSP group with negative sputum cultures (65% vs 34%; p = 0.014) and with MAC negative group (65% vs 28%; p = 0.009).

CONCLUSIONS

Patients diagnosed as pulmonary MAC disease in the follow-up duration tend to show solitary nodular pattern or NB pattern without cavitation. In FSN patients with NB pattern, more lung lobes were involved in the first study, suggesting subsequent MAC infection onto the underlying ectatic bronchi.

Epidemiology and clinical features of pulmonary nontuberculous mycobacteriosis in Nagasaki, Japan

BACKGROUND AND OBJECTIVES

Recent reports indicate that the incidence of nontuberculous mycobacterial-lung disease (NTM-LD) is increasing. This study aimed to investigate the epidemiology and clinical features of NTM-LD patients in Nagasaki prefecture, Japan to identify the negative prognostic factors for NTM-LD in Japan.

METHODS

The medical records of patients newly diagnosed with NTM-LD in eleven hospitals in Nagasaki prefecture between January 2001 and February 2010 were reviewed. Data regarding the annual population of each region and the incidence of all forms of tuberculosis were collected to assess geographic variations in NTM-LD incidence, isolates, and radiological features.

RESULTS

A total 975 patients were diagnosed with NTM-LD. The incidence increased over the study period and reached 11.0 and 10.1 per 100,000 population in 2008 and 2009, respectively. M. intracellulare was the most common pathogen in the southern region, and M. avium most common in other regions. The most common radiographic pattern was the nodular-bronchiectatic pattern. Age >60 years, body mass index <18.5 kg/m2, underlying lung disease, and cavitary pattern were the negative prognostic factors at the 1-year follow-up.

CONCLUSIONS

The incidence of NTM-LD has been increasing in Nagasaki prefecture. The isolates and radiographic features of patients vary markedly by region.

Acquired immune-deficiency syndrome with focal onset of Mycobacterium avium infection displaying a histological/genetic pattern of disseminated mycobacteria

A 66-year-old man with human immunodeficiency virus (HIV) infection was admitted for treatment of Pneumocystis pneumonia. Upon admission, a tumor mass adjacent to the thoracic descending aorta was revealed on computed tomography. Histology revealed an exudative granuloma with histiocytes packed with numerous acid-fast bacilli. Mycobacterium avium was isolated from the tissue. A genetic examination of the isolates demonstrated this strain to be located in the cluster consisting of strains that cause systemic infection. The patient's baseline CD4+ cell count was 9/μL and the HIV-RNA viral load was 43,800 copies/mL. This case suggests the possibility of a localized onset of disseminated M. avium infection.

[Lung pathology in HIV-associated infections]

The lung and intrathoracic lymph nodes taken from 153 persons who had taken from HIV infection at the age of 20 to 32 years, with the development of various infectious diseases were examined. Secondary diseases were of generalized progressive pattern. Among these diseases accompanied by pulmonary lesions tuberculosis, as well as bacterial pneumonias, cytomegalovirus infection, pneumocystic pneumonia, cryptococcosis, and non-tuberculous mycobacterial diseases were most common. Lung tissue reactions at terminal stages of HIV infection were polymorphic, which had been caused by severe immunodeficiency, a change in the course of diseases, obliteration of typical morphological signs, and a mixed lung lesion. This makes the differential diagnosis of diseases difficult and requires a comprehensive study of specimens in each specific case, by widely employing additional methods and stains to detect different pathogens.

Histopathological classification of systemic Mycobacterium avium complex infections in slaughtered domestic pigs

The aim of this study was to classify the histopathological features of pigs infected with Mycobacterium avium complex (MAC). We used slaughtered pig organs systemically infected with MAC. The results showed granulomatous lesions which were observed predominantly in the digestive organs and regional lymph nodes rather than respiratory organs. The histological picture showed a wide range of granulomatous stages from exudative to fibrotic reactions to the MAC infection. Eosinophils and giant cells were characteristically observed in the exudative reactions. The histopathological type in primary focus tended to be maintained in the respective organs. Most strains with the same genotype showed pathogenicity for guinea pigs irrespective of the type of granuloma. Although these findings suggest that different stages of a granulomatous lesion originating from the same causative agent might influence histological patterns, other possibilities such as the hereditary background of the host, or the effects of viral infections should be considered.

Probable cerebral Mycobacterium avium complex-related immune reconstitution inflammatory syndrome in an HIV-infected patient

The advent of highly active anti-retroviral therapy (HAART) has reduced both the morbidity and incidence of acquired immunodeficiency syndrome (AIDS)-related central nervous system (CNS) diseases. However, some patients seem to suffer paradoxical clinical deterioration after starting HAART, known as immune reconstitution inflammatory syndrome (IRIS). We report a rare case of probable Mycobacterium avium complex (MAC) infection of the brain in a patient with AIDS who had been treated effectively for probable pulmonary and cerebral MAC infection, with both lesions recurring after significant decreases in plasma human immunodeficiency virus type-1 viral load following initiation of HAART. This case appears to represent the first precise clinicopathological description of severe ventriculo-encephalitis in CNS MAC-related IRIS.

I/St mice hypersusceptible to Mycobacterium tuberculosis are resistant to M. avium

We previously demonstrated that mice of the I/St strain are extremely susceptible to Mycobacterium tuberculosis, as well as to the taxonomically distant intracellular bacteria Chlamydia pneumoniae and Salmonella enterica. To broaden our knowledge about the control of susceptibility to intracellular pathogens, we studied the infection caused by Mycobacterium avium virulent strain 724 in a panel of inbred mouse strains and found that I/St mice are resistant to M. avium. By comparing I/St mice with B6 mice, we demonstrated that (i) B6 mice are much more susceptible to infection caused by M. avium in terms of bacterial multiplication in the lung tissue and severity of lung pathology; (ii) in B6 mice but not in I/St mice infection leads to prolonged leukocyte infiltration of the lung tissue, development of necrotic lung granulomata, and lethality; and (iii) the unfavorable infectious course in B6 mice is accompanied by elevated production of gamma interferon, tumor necrosis factor alpha, and especially interleukin-12 in the lungs. Importantly, M. avium-resistant I/St mice carry a functional r allele of the Slc11a1 (formerly Nramp1) gene, while B6 mice have the Slc11a1(s) genotype. Segregation genetic analysis of (I/St x B6) F2 hybrids demonstrated that susceptibility or resistance to infection caused by M. avium largely depended upon the Slc11a1 genotype and that other genetic traits had a relatively weak influence. This close-to-monogenic pattern differs sharply from the host control of many other intracellular bacterial infections, for which the involvement of numerous quantitative trait loci has been ubiquitously observed.

Mycobacterial spindle cell pseudotumor of the skin

BACKGROUND

Mycobacterial spindle cell pseudotumor is a rare tumor-like lesion characterized by the proliferation of spindle cells engorged with mycobacterial microorganisms. To our knowledge, only a few cases of cutaneous lesions have been described in the literature.

CASE REPORT

A 58-year-old Japanese woman presented with a nodule in her left forearm. She had systemic lupus erythematosus and interstitial pneumonia for 17 years, treated with prednisolone and azathioprine. She was also receiving insulin treatment for diabetes mellitus.

RESULTS

Histologically, the lesion was located in the deep dermis with extension into the subcutaneous fat tissue and was composed mainly of spindle cells focally showing a vaguely storiform pattern. In limited focal areas, foam cells, epithelioid histiocytes, and multinucleated giant cells were seen sparsely. Ziehl-Neelsen staining showed numerous acid-fast bacilli within the spindle cells and epithelioid histiocytes. The acid-fast bacilli were determined by culture and polymerase chain reaction to be Mycobacterium intracellulare.

CONCLUSIONS

We emphasize that mycobacterial spindle cell pseudotumor should be included in the differential diagnoses of a spindle cell lesion in the skin, especially in immunosuppressed patients.

Hepatoportal venopathy due to disseminated Mycobacterium avium complex infection in a child with IFN-gamma receptor 2 deficiency

The control of intracellular microorganisms such as mycobacteria is largely dependent on the adaptive immune response, specifically the interaction of T helper cells and antigen presenting cells such as macrophages. The interferon gamma (IFN-gamma) pathway activation is crucial for containment and killing of mycobacteria, as evidenced by the fact that defects in this pathway often result in profound infections with both tuberculous and non-tuberculous mycobacteria. We herein report a case of a child with autosomal recessive IFN-gamma receptor 2 (IFN-gammaR2) deficiency who developed hepatic venopathy secondary to disseminated Mycobacterium avium complex (MAC) infection.

Palatial erosion caused by Mycobacterium Avium complex in a human immunodeficiency virus infected child

Oral manifestations of Mycobacterium Avium complex (MAC) are rare and have only been described in adults. Here we report a 10-year-old female with advanced human immunodeficiency virus infection, who presented with disseminated MAC and an erosive left palate defect.

[Mycobacterium avium complex infection which need to distinguish from lung cancer]

A 42 year old female was admitted to our hospital due to abnormal shadow on her chest X-ray. She had no symptoms. Chest X-ray and computed tomography (CT) scan revealed solitary nodule on left S10. Bronchofiberscopy was perfomed, but it could not establish pathological diagnosis. Thoracoscopic surgery was performed. It revealed that solitary nodule was Mycobacterium avium infection. Majority cases of Mycobacterium avium infection showed multiple nodules or infiltration shadows on bilateral lungs. But in our case, CT scan showed a solitary nodule, causing differential diagnosis from lung cancer to be difficult.

[Mycobacteriosis as zoonotic disease--comparative pathological study on Mycobacterium avium complex infection]

Mycobacterium avium complex (MAC) infection has been giving major impact on human health. MAC infection is also one of zoonosis transmittable from environmental reservoirs to domestic animal such as pig, and from wildlife to human. Although the relationship between pig MAC infection and human MAC infection has been suggested, it has not been clarified about difference of pathogens, differences in the pathogenesis of the disease, and differences in pathological findings between them. As one of zoonosis, hog farms suffer from the epidemic in pig population and it may causes huge economical loss. At the same time, from pig to human transmission of MAC has been worried. Therefore, the control of MAC infection among hog farms is a very important issue both for pig industries and for human public health. We have demonstrated that the specific MAC strains can spread through pig market in the main island of Okinawa. In pig MAC infection, pathogens are infected orally, and granulomatous lesions are formed in abdominal lymph nodes. Subsequently, it spreads lymphogenously or hematogenously and forms disseminated disease. Pathologically, calcified lesion was formed within several months. These findings are quite different from human MAC disease, in which the infection was caused by inhalation, and form granulomatous lesions in lungs, and rarely cause lymph node swellings. Since the pathogenesis of human MAC respiratory infection has not been well clarified, it may be very important to examine the mechanism of pig MAC infection to find out some clues to explain the mechanism of human MAC infection.

Portal hypertension and granulomatous liver disease in a lung transplant recipient due to disseminated atypical mycobacterial infection

The incidence of atypical mycobacterial infection among solid organ transplant recipients is increasing. While lung transplant recipients in particular are at greater risk of atypical mycobacterial infection than other solid organ transplant recipients, it is typically confined to the lung and disseminated infection remains quite rare. We describe a case of disseminated Mycobacterium avium-complex (MAC) in a lung transplant recipient presenting as granulomatous liver disease with signs of portal hypertension. After identification of the infection and institution of proper therapy, the patient had significant improvement in both clinical signs of portal hypertension and liver function tests. Current literature suggests a favorable prognosis in most cases of MAC infection in lung transplant recipients with appropriate treatment. This case highlights the need to maintain an elevated index of suspicion for atypical pathogens with unusual clinical presentations among the lung transplant population.

The morphological spectrum of lymphadenopathy in HIV infected patients

AIMS

To study the histological spectrum of lymphadenopathy in human immunodeficiency virus (HIV) infected Thai patients.

METHODS

Lymph nodes from 55 HIV infected patients were accessioned over a 19 month period in two pathology laboratories in Bangkok, Thailand. These were examined with H&E, Ziehl-Neelsen, periodic acid-Schiff (PAS), PAS with diastase (PAS/D), Gram and methenamine stains.

RESULTS

Six reaction patterns were observed: (1) classic necrotising granulomas (30 cases); (2) extensive necrosis with minimal granulomatous response (5 cases); (3) sarcoid-like non-necrotising granulomas (5 cases); (4) foamy macrophage or pseudo-Gaucher cell response (5 cases); (5) inflammatory pseudotumour-like proliferation (3 cases); and (6) non-specific lymphoid hyperplasia (7 cases). Myriads of intracellular, long, slender acid-fast bacilli were found in those cases with the pseudo-Gaucher cell and inflammatory pseudotumour-like response, while variable numbers of bacilli were identified in those cases with non-necrotising sarcoid-like granulomas. Few scattered acid-fast bacilli were found in five cases with necrotising granulomas. In one case, yeast-like organisms in keeping with Cryptococcus were identified. No organisms were identified in the cases showing lymphoid hyperplasia, extensive necrosis and minimal granulomatous response, and in the remaining cases of classic necrotising granulomas.

CONCLUSIONS

The wide spectrum of histological changes in HIV-associated lymphadenomegaly requires recognition, particularly as the majority were associated with acid-fast organisms, mostly in keeping with the morphological features of Mycobacterium avium-M. intracellulare complex that was distinctively stained by Grocott methenamine-silver, Gram and PAS stains. The histological changes mimic those of infarction and other infective lymphadenitis, sarcoidosis, Whipple's disease, inflammatory pseudotumour and spindle cell neoplasms.

Solitary pulmonary granuloma caused by Mycobacterium avium-intracellulare complex

OBJECTIVES

To analyse the clinical features and high resolution computed tomography (HRCT) findings of solitary pulmonary granulomas caused by the Mycobacterium avium-intracellulare (MAI) complex.

METHODS

We retrospectively analysed a series of 73 consecutive patients with solitary pulmonary granuloma and negative sputum smear and culture results, in whom the diagnosis was established by histological examination of specimens obtained by partial pulmonary resection or lobectomy. We compared the clinical features and HRCT findings of the solitary pulmonary granulomas definitively diagnosed to be caused by the MAI complex with those of granulomas of other causes by univariate and multivariate analyses.

RESULTS

In this study series of 24 patients with solitary pulmonary granuloma, the aetiological agent was established as being the MAI complex. According to the results of the multivariate analysis, 'female sex', 'pleural indentation' and 'lobulation' on the HRCT images were significantly associated with solitary pulmonary granuloma caused by the MAI complex.

CONCLUSION

This study demonstrated several characteristics of solitary pulmonary granulomas caused by the MAI complex, and suggested that it might be a subtype of pulmonary MAI complex infection without the typical radiographic features of the infection.

Chronic necrotizing pulmonary aspergillosis as a complication of pulmonary Mycobacterium avium complex disease

OBJECTIVE AND BACKGROUND

To investigate the characteristic clinical features of chronic necrotizing pulmonary aspergillosis (CNPA) as a complication of pulmonary Mycobacterium avium complex (MAC) disease.

METHODS

Clinical analysis of nine cases without a history of old pulmonary tuberculosis in whom CNPA was found to be a complication during the follow-up period for MAC disease.

RESULTS

The average duration from the diagnosis of pulmonary MAC disease to the diagnosis of CNPA was 36.0 months. Five patients received antituberculous therapy including clarithromycin for pulmonary MAC disease, but this treatment was ineffective in most. A positive culture for Aspergillus spp. from sputum and a bronchoscopic specimen and clinical evidence of a chronic infective process were recognized in all cases at the time of detection of CNPA. Serological fungal examinations for anti-Aspergillus IgG antibody were initially negative and became positive in all cases during the follow-up period of pulmonary MAC disease. The presence of CNPA surrounding the cavity previously caused by MAC was characterized by local thickening of the cavity with a fungus ball and the appearance of an infiltration shadow surrounding the cavity. In most of the cases, CNPA was at first treated with oral itriconazole and then with i.v. infusion of micafungin, but the clinical efficacy was generally poor.

CONCLUSION

The results of this study showed that during the long follow-up period of patients with pulmonary MAC disease it is important to not only carry out serological examinations, but also perform radiological examinations using chest CT.

The Expanding Spectrum of Mycobacterium avium Complex-Associated Pulmonary Disease

Nontuberculous mycobacteria (NTM) are increasingly recognized as important pulmonary pathogens. Mycobacterium avium intracellulare complex (MAC) causes most lung infections due to NTM. Patients with preexisting lung disease or immunodeficiency are at greatest risk for developing MAC infection. The majority of MAC pulmonary cases, however, occur in immunocompetent elderly women in association with nodular infiltrates and bronchiectasis. More recently, pulmonary disease has also been described in immunocompetent patients after exposure to MAC-contaminated hot tubs. We describe a case of aggressive MAC lung disease in a young immunocompetent female patient without preexisting lung disease whose clinical and pathologic characteristics do not fit into any of these categories and may represent a unique manifestation of MAC lung disease.

Pulmonary Mycobacterium intracellulare disease with a solitary pulmonary nodule detected at the onset of pneumothorax

A 61-year-old man with a past history of pulmonary emphysema 6 years earlier was admitted to the emergency department at our hospital because of cough and dyspnea. Left pneumothorax was recognized on a chest radiograph. After his admission to the emergency department, chest drainage was inserted and the left lung was expanded. Afterwards, a nodular shadow (>1.5 cm) was found in the left upper lobe, and differentiation from pulmonary adenocarcinoma was required. As a definite diagnosis could not be made by bronchoscopy, video-assisted thoracoscopic surgery was performed, and a solitary nodule in the left upper lobe was resected. Histologically, a caseating epitheloid granuloma with acid-fast bacilli was found. Regarding the causative pathogen, Mycobacterium intracellulare was identified from the surgically resected specimen. We have reported a peculiar case of pulmonary M. intracellulare disease, detected at the onset of left secondary pneumothorax caused by pulmonary emphysema, which required differentiation from pulmonary adenocarcinoma.

Regulation of granuloma fibrosis by nitric oxide during Mycobacterium avium experimental infection

Collagen deposition within granulomas formed after Mycobacterium avium infection was analysed on histological sections stained with Masson's trichrome using acquired computerized image analysis and a program that was specifically designed for that purpose. Comparison was made between immunocompetent C57BL/6 mice and mice genetically deficient in the inducible nitric oxide (NO) synthase gene (iNOS(-/-) mice) infected with either a highly virulent strain or a moderately virulent strain of M. avium. iNOS-deficient mice were more resistant to the highly virulent strain than control C57B1/6 mice, but both strains were equally susceptible to the less virulent M. avium strain. Collagen distribution in the granuloma was found in the cuff surrounding the granuloma in an area rich in lymphoid cells as well as inside the granuloma itself, conferring a mesh-like structure within that lesion. It was seen that iNOS(-/-) mice induced a higher collagen deposition than C57BL/6 mice and that such collagen deposition varied with the mycobacterial strain used to infect the animals.

[A case of endobronchial lesion due to infection with Mycobacterium intracellulare]

A 53-year-old man was hospitalized in April 2001 because of left cervical lymphadenopathy and a mass shadow in the left lingular segment. Bronchoscopy revealed an elevated lesion in the left main bronchus, but a biopsy showed no specific findings. A left cervical lymph node biopsy revealed lymphoid hyperplasia only and no malignancy. After the patient was discharged, bronchial irrigation solution from the left lingular segment was found to be positive for Mycobacterium intracellulare. In July 2001 the shadow in the left lingular segment had worsened, and bronchoscopy was performed again. This revealed ulceration in the left main bronchus and edematous narrowing of the bronchial lumen at the opening of the lingular segment. A granulated lesion accompained by severe inflammation was seen in a biopsied specimen taken from the same site. Bronchial lesion induced by an acid-fast-stain positive nontuberculosis mycobacteria was noted. Treatment with rifampicin (RFP), clarithromycin (CAM), ethambutol (EB), and streptomycin (SM) was started, but a rash most likely caused by RFP developed, and RFP was replaced by ciprofloxacin (CPFX). The treatment was continued and symptoms improved. Since non-tuberculous mycobacteriosis accompanied with bronchial lesions is rare, a case report was made.

Increased serum level of vascular endothelial growth factor in Mycobacterium avium complex infection

OBJECTIVE

Pulmonary infection caused by Mycobacterium avium complex (MAC) is one of the granulomatous diseases which are associated with the expression of vascular endothelial growth factor (VEGF). The aim of the present study was to clarify the association of VEGF with the pathogenesis of MAC infection.

METHODOLOGY

The serum VEGF levels in 46 patients with pulmonary MAC infection were compared with those in 16 normal control subjects. Pulmonary lesions were evaluated using chest CT. In 20 patients, after treatment, serum VEGF levels were measured and chest CT performed again to evaluate pulmonary response to treatment.

RESULTS

Infected patients had higher serum VEGF levels than controls (435.2 +/- 29.1 vs. 167.0 +/- 10.6 pg/mL, P < 0.0001), and serum VEGF level correlated with the extent of disease. The serum VEGF levels in 14 patients who underwent treatment and exhibited an improvement in their pulmonary lesions decreased significantly compared with the results pretreatment (509.0 +/- 60.7 vs. 303.6 +/- 65.3 pg/mL, P = 0.0092). In infected patients, alveolar macrophages, epithelioid cells and multinucleated giant cells exhibited VEGF overexpression on immunohistochemical staining.

CONCLUSIONS

This study suggests that VEGF may be associated with the pathogenesis of pulmonary MAC infection. Additionally, serum VEGF levels may be a useful surrogate marker for evaluating the extent of disease and of the response to treatment.

Mycobacterial synovitis caused by slow-growing nonchromogenic species: eighteen cases and a review of the literature

CONTEXT

Slow-growing nonchromogenic mycobacterial species are an infrequent cause of soft tissue infection. Because these organisms are rare, they are not often initially considered in the differential diagnosis of synovitis.

OBJECTIVE

To evaluate the clinical and pathologic characteristics of patients with synovitis resulting from slow-growing nonchromogenic mycobacterial species.

DESIGN

A 20-year retrospective review of records from The Methodist Hospital Microbiology Laboratory identified 18 culture-positive cases of synovitis that resulted from slow-growing nonchromogenic mycobacteria, including 14 caused by Mycobacterium avium complex, 1 caused by Mycobacterium malmoense, 1 caused by Mycobacterium haemophilum, and 2 caused by Mycobacterium nonchromogenicum isolates. In addition, a comprehensive literature search revealed an additional 48 cases of synovitis caused by slow-growing nonchromogenic mycobacteria.

RESULTS

The historic literature described the majority of the 48 patients as previously healthy, elderly individuals with a several-month history of monoarticular pain and swelling in the small joints of the upper extremity. In contrast, the current series demonstrated the probable role of multiple chronic coexisting medical conditions in promoting disease susceptibility. These patients were also unique in their significantly younger age distribution and diversity of infection sites. Histologic examination and direct acid-fast bacteria stains generally did not aid the diagnosis. Amputation was performed in 2 patients because of delayed identification of disease.

CONCLUSIONS

The current series demonstrates that difficult identification and infrequent occurrence cause these organisms to be overlooked by physicians and laboratory personnel. A heightened clinical suspicion for slow-growing nonchromogenic mycobacterial species is necessary when routine culture and histopathologic findings do not readily isolate an organism, or when the patient does not respond to antibiotic and anti-inflammatory treatment.

[Bacteriological and pathological analysis on the pathogenetic factors for cavitary and nodular bronchiectatic type of pulmonary Mycobacterium avium-intracellulare complex disease]

A total of 101 strains of Mycobacterium avium complex (MAC), consisting of 86 M. avium and 15 M. intracellulare strains, were examined by DNA sequencing. The frequency of radiological types [cavitary (Cav) type and nodular bronchiectatic (NB) type] was similar in each species, thus, both species are equal causes of the two radiological types of MAC disease. We also examined serovars of the isolated strains using extracted glycopeptidelipid antigens and thin layer chromatography. Cav type patients discharged a single serovar MAC, while NB type patients discharged two serovar MACs simultaneously. RFLP pattern obtained by the use of IS1245, revealed no clustering of the strains specific for Cav type and NB type. Histopathological examinations of the bronchial lesions in 40 MAC cases and 49 multi-drug resistant tuberculosis (MDR-TB) cases were performed on the surgically removed lung specimens. Lymphocytic infiltration, epithelioid cell granuloma formation, epithelial desquamation and ulceration, as well as smooth muscle atrophy as a cause of bronchiolectasis, were observed more often and were more severe in the peripheral bronchial walls of the NB type than the Cav type of MAC, and as compared with those of MDR-TB cases.

Combined effects of ATP on the therapeutic efficacy of antimicrobial drug regimens against Mycobacterium avium complex infection in mice and roles of cytosolic phospholipase A2-dependent mechanisms in the ATP-mediated potentiation of antimycobacterial host resistance

ATP, which serves as a mediator of intramacrophage signaling pathways through purinoceptors, is known to potentiate macrophage antimycobacterial activity. In this study we examined the effects of ATP in potentiating host resistance to Mycobacterium avium complex (MAC) infection in mice undergoing treatment with a drug regimen using clarithromycin and rifamycin and obtained the following findings. First, the administration of ATP in combination with the clarithromycin and rifamycin regimen accelerated bacterial elimination in MAC-infected mice without causing changes in the histopathological features or the mRNA expression of pro- or anti-inflammatory cytokines from those in the mice not given ATP. Second, ATP potentiated the anti-MAC bactericidal activity of macrophages cultivated in the presence of clarithromycin and rifamycin. This effect of ATP was closely related to intracellular Ca2+ mobilization and was specifically blocked by a cytosolic phospholipase A2 (cPLA2) inhibitor, arachidonyl trifluoromethylketone. Third, intramacrophage translocation of membranous arachidonic acid molecules to MAC-containing phagosomes was also specifically blocked by arachidonyl trifluoromethylketone. In the confocal microscopic observation of MAC-infected macrophages, ATP enhanced the intracellular translocation of cPLA2 into MAC-containing phagosomes. These findings suggest that ATP increases the host anti-MAC resistance by potentiating the antimycobacterial activity of host macrophages and that the cPLA2-dependent generation of arachidonic acid from the phagosomal membrane is essential for such a phenomenon.

Infectious bulla of the lung caused by Mycobacterium intracellulare

A healthy 24-year-old man who was admitted to our hospital was suspected of having an infectious bulla of the lung because an intrabullous effusion was seen on a chest radiograph. A bulla of the right lung had been found 2 years earlier during a periodic health examination. On a chest radiograph, a bullous lesion with a niveau-like shadow (14 x 7 cm) was noted in the right lower lobe of the lung. On puncture aspiration, the bulla fluid was found to be exudative and contained mostly lymphocytes. A smear examination for acid-fast bacilli was positive, as was polymerase chain reaction (PCR) examination for Mycobacterium intracellulare. Therefore, a diagnosis of infectious lung bulla caused by M. intracellulare was made. A right lower lobectomy was performed. On macroscopic examination of the resected lesion, the area surrounding the bulla was whitish in color, and microscopic examination of this area showed a caseating epitheloid granuloma with acid-fast bacilli. We report this case because there have been no previous reports in the literature of infectious lung bulla caused by M. intracellulare although there have been several reports dealing with lung bulla caused by Mycobacterium tuberculosis.

Pseudo-Gaucher cells in mycobacterial infection: a report of two cases

This report describes two cases of mycobacterial infection with pseudo-Gaucher cells. Both patients had no clinical evidence of inherited Gaucher disease. The first case was a patient with AIDS and Mycobacterium avium intracellulare involving the lung, spleen, and bone marrow. The bone marrow aspirates showed many histiocytes with needle-like inclusions. Acid fast staining showed that these histiocytes contained acid fast bacilli. Bone marrow biopsies revealed granulomatous lesions with aggregates of foamy histiocytes. The second case was an alcoholic patient with Mycobacteriumkanasassi infection involving the lung and lymph nodes. The lymph node aspirates showed infiltration of the same cells with acid fast bacilli in the cytoplasm.

[A case of hypersensitivity pneumonitis caused by inhalation of Mycobacterium avium from a home bath with a circulating water system]

A 26-year-old man presented with complaints of exertional dyspnea and cough. The patient has already been given corticosteroids at a previous hospital. Chest CT revealed small centrilobular nodules with diffuse ground-glass opacities in both lungs. Lung biopsy specimens at thoracoscopy revealed non-necrotizing granulomas, patchy foci of mononuclear cell infiltration and fibrous thickening of alveolar septa, and Masson's bodies in bronchioles. Sputum culture showed the growth of Mycobacterium avium complex (MAC). Culture of water from the bath tub of his home showed MAC. Administration of antituberculous drugs and corticosteroids, and avoidance of bathing at home resulted in the improvement of his symptoms and CT findings. We believe the case is hypersensitivity pneumonitis to MAC in an immunocompetent patient, simulating hot tub lung. Hypersensitivity pneumonitis caused by MAC is rare in Japan.

[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.

A Case of Mycobacterium avium Complex Pulmonary Disease in an Immunocompetent Host

Mycobacterium avium complex is the most common of nontuberculous mycobacterium capable of causing disease in humans. The manifestations can vary from asymptomatic exposure to hypersensitivity pneumonitis to advanced fibrocavitary disease. We describe the case of a 37-year-old male with advanced cavitary disease from Mycobacterium avium complex. The patient had no previous history of pulmonary disease, but did have a history of snorting crushed Lortab (hydrocodone/acetaminophen) tablets and we postulate that possible injury to the lung from talc or other chemicals in the tablets may have predisposed him to develop Mycobacterium avium pulmonary disease.