CT features of pulmonary Mycobacterium avium complex infection

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Early Warning Information for Severe and Critical Patients With COVID-19 Based on Quantitative CT Analysis of Lung Segments

Background: The coronavirus disease 2019 (COVID-19) outbreak is spreading rapidly around the world.

Purpose: We aimed to explore early warning information for patients with severe/critical COVID-19 based on quantitative analysis of chest CT images at the lung segment level.

Materials and Methods: A dataset of 81 patients with coronavirus disease 2019 (COVID-19) treated at Wuhan Wuchang hospital in Wuhan city from 21 January 2020 to 14 February 2020 was retrospectively analyzed, including ordinary and severe/critical cases. The time course of all subjects was divided into four stages. The differences in each lobe and lung segment between the two groups at each stage were quantitatively analyzed using the percentage of lung involvement (PLI) in order to investigate the most important segment of lung involvement in the severe/critical group and its corresponding time point.

Results: Lung involvement in the ordinary and severe/critical groups reached a peak on the 18th and 14th day, respectively. In the first stage, PLIs in the right middle lobe and the left superior lobe between the two groups were significantly different. In the second stage and the fourth stage, there were statistically significant differences between the two groups in the whole lung, right superior lobe, right inferior lobe and left superior lobe. The rapid progress of the lateral segment of the right middle lobe on the second day and the anterior segment of the right upper lobe on the 13th day may be a warning sign for severe/critical patients. Age was the most important demographic characteristic of the severe/critical group.

Conclusion: Quantitative assessment based on the lung segments of chest CT images provides early warning information for potentially severe/critical patients.

Imaging characteristics of nontuberculous mycobacterial pulmonary nodules

Introduction: Nontuberculous mycobacteriosis (NTM) of the lungs can develop nodules. In order to clarify some of the characteristics of lung NTM nodules, we examined volume doubling time (VDT) and maximum standardized uptake value (SUVmax) in positron emission tomography (PET) of pathologically diagnosed NTM nodules.Methods: From November 2012 to August 2018, clinical and radiological information were retrospectively investigated in 8 patients who were surgically resected and diagnosed as NTM. These eight patients were followed up until November 2020 and were confirmed to have no appearance of lung cancer or reappearance of lung NTM nodules. The VDT was calculated using the Schwartz formula.Results: The median maximum diameter of the nodule at the time of the first CT scan was 16.0 (range: 9.9-20.0) mm. The median maximum diameter of the nodule on CT performed before the surgical biopsy was 18.8 (range: 10.4-32.8) mm. The median doubling time calculated from these results was 203 (range: 20-568) days. Caseous granulomas and acid-fast bacilli were histologically confirmed in all 8 patients. Culture of excised nodules revealed Mycobacterium intracellulare in 5 patients and Mycobacterium avium in 3 patients. Six patients received PET, and median SUVmax was: 7.0 (range: 3.3-21.0). Median VDT was around 200 days. Some patients had irregular-shaped nodules.Conclusions: CT/PET-CT characteristics of lung nodules are not reliable in differentiating lung NTM nodules from malignant ones. To avoid unnecessary resection, it may be better to collect various information on imaging findings in the nodule itself and in opacities other than the nodule.

Radiological approach to cavitary lung lesions

Cavitary lesions in the lung are not an uncommon imaging encounter and carry a broad differential diagnosis that includes a wide range of pathological conditions from cancers, infections/inflammatory processes to traumatic and congenital lung abnormalities. In this review article, we describe a comprehensive approach for evaluation of cavitary lung lesions and discuss the differential diagnosis in the light of radiological findings.

Comparison of the chest computed tomography findings between patients with pulmonary tuberculosis and those with Mycobacterium avium complex lung disease

BACKGROUND

Since the computed tomography (CT) findings of nontuberculous mycobacterial lung disease are similar to those of pulmonary tuberculosis (PTB), we often have difficulty differentiating the two. In this study, we compared the differences in chest CT findings and their locations between cases of PTB and Mycobacterium avium complex lung disease (MACLD).

METHODS

The subjects were 100 MACLD patients and 42 PTB patients treated at our hospital from May 2005 to August 2015. The CT findings were retrospectively evaluated.

RESULTS

PTB more frequently showed lung shadows with calcification inside the lesion, calcification of the mediastinal/hilar lymph node, and pleural effusion on CT than MACLD, while extensive bronchiectasis and granular/large shadows connected to bronchiectasis were more frequently observed with MACLD than PTB. For cavitary lesions, the thinnest part of the cavity wall with MACLD was thinner than that with PTB. Granular shadows, large shadows, and bronchiectasis were typically distributed to the right upper lobe and left upper division in PTB cases vs. the right intermediate lobe and left lingula in MACLD.

CONCLUSIONS

Chest CT findings would therefore be useful for distinguishing PTB and MACLD when typical findings are observed.

Comparison of chest CT findings in nontuberculous mycobacterial diseases vs. Mycobacterium tuberculosis lung disease in HIV-negative patients with cavities

Objectives

This article focuses on the differences between CT findings of HIV-negative patients who have cavities with nontuberculous mycobacteria (NTM) disease and those with Mycobacterium tuberculosis infections (TB).

Methods

We retrospectively reviewed 128 NTM disease patients (79 males and 49 females) with cavities in chest CT, matched for age and gender with 128 TB patients in the same period. Sputum cultures of all patients were positive for pathogens. Two independent chest radiologists evaluated the characteristics of the largest cavity and related factors.

Results

Interobserver agreement was excellent (κ value, 0.853–0.938). Cavity walls in NTM disease were significantly thinner (6.9±4 mm vs 10.9±6 mm, P<0.001) and more even (the ratio of thickness, 2.6±1 vs 3.7±2, P<0.001) than those in TB. The thickening of adjacent pleura next to the cavity was also significantly thicker in NTM than TB (P<0.001). However, in the multivariate analysis, thickening of adjacent pleura was the only significant factor among the representative cavity findings (Odds ratio [OR], 6.49; P<0.001). In addition, ill-defined tree-in-bud nodules (OR, 8.82; P<0.001), number of non-cavitary nodules (≥10mm) (OR, 0.72; P = 0.003), and bronchiectasis in the RUL (OR, 5.3; P = 0.002) were significantly associated ancillary findings with NTM disease in the multivariate analysis.

Conclusions

The major cavities in NTM disease generally have thinner and more even walls than those in TB. When cavities are associated with adjacent pleural thickening, ill-defined satellite tree-in-bud nodules, or fewer non-cavitary nodules ≥10 mm, these CT findings are highly suggestive of NTM disease rather than TB.

Adult Patients With Bronchiectasis: A First Look at the US Bronchiectasis Research Registry

OBJECTIVES

We sought to describe the characteristics of adult patients with bronchiectasis enrolled in the US Bronchiectasis Research Registry (BRR).

METHODS

The BRR is a database of patients with non-cystic-fibrosis bronchiectasis (NCFB) enrolled at 13 sites in the United States. Baseline demographic, spirometric, imaging, microbiological, and therapeutic data were entered into a central Internet-based database. Patients were subsequently analyzed by the presence of NTM.

RESULTS

We enrolled 1,826 patients between 2008 and 2014. Patients were predominantly women (79%), white (89%), and never smokers (60%), with a mean age of 64 ± 14 years. Sixty-three percent of the patients had a history of NTM disease or NTM isolated at baseline evaluation for entry into the BRR. Patients with NTM were older, predominantly women, and had bronchiectasis diagnosed at a later age than those without NTM. Gastroesophageal reflux disease (GERD) was more common in those with NTM, whereas asthma, primary immunodeficiency, and primary ciliary dyskinesia were more common in those without NTM. Fifty-one percent of patients had spirometric evidence of airflow obstruction. Patients with NTM were more likely to have diffusely dilated airways and tree-in-bud abnormalities. Pseudomonas and Staphylococcus aureus isolates were cultured less commonly in patients with NTM. Bronchial hygiene measures were used more often in those with NTM, whereas antibiotics used for exacerbations, rotating oral antibiotics, steroid use, and inhaled bronchodilators were more commonly used in those without NTM.

CONCLUSIONS

Adult patients with bronchiectasis enrolled in the US BRR are described, with differences noted in demographic, radiographic, microbiological, and treatment variables based on stratification of the presence of NTM.

Multiple Cavitary Pulmonary Nodules Caused by Mycobacterium intracellulare

Nontuberculous mycobacteria (NTM) have been increasingly recognized as an important cause of chronic pulmonary infections. The Mycobacterium avium complex (MAC), which is composed of two species, Mycobacterium avium and Mycobacterium intracelluare, is the most commonly encountered pathogen associated with NTM lung disease. MAC pulmonary infection typically presents in a fibrocavitary form or a nodular bronchiectatic form. However, there have been atypical presentations of MAC pulmonary infections, including solitary pulmonary nodules (SPN). There have been several previous reports of SPN due to MAC infection in the United States, Japan, and Korea. In 2009, Sekine and colleagues reported a case of MAC pulmonary infection presenting with multiple nodules. To date, however, there have been no cases of NTM lung infection with multiple cavitary pulmonary nodules, and neither a fibrotic change nor nodular bronchiectasis. The present case showed a multiple cavitating nodular lung infection due to MAC, which is very rare and different from the typical presentation of MAC pulmonary infections. We also showed that percutaneous transthoracic needle aspiration can be a useful diagnostic tool to evaluate a case of multiple cavitary nodules.

Update on pulmonary disease due to non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) are emerging worldwide as significant causes of chronic pulmonary infection, posing a number of challenges for both clinicians and researchers. While a number of studies worldwide have described an increasing prevalence of NTM pulmonary disease over time, population-based data are relatively sparse and subject to ascertainment bias. Furthermore, the disease is geographically heterogeneous. While some species are commonly implicated worldwide (Mycobacterium avium complex, Mycobacterium abscessus), others (e.g., Mycobacterium malmoense, Mycobacterium xenopi) are regionally important. Thoracic computed tomography, microbiological testing with identification to the species level, and local epidemiology must all be taken into account to accurately diagnose NTM pulmonary disease. A diagnosis of NTM pulmonary disease does not necessarily imply that treatment is required; a patient-centered approach is essential. When treatment is required, multidrug therapy based on appropriate susceptibility testing for the species in question should be used. New diagnostic and therapeutic modalities are needed to optimize the management of these complicated infections.

Broncho-Pleural Fistula with Hydropneumothorax at CT: Diagnostic Implications in Mycobacterium avium Complex Lung Disease with Pleural Involvement

Objective

To determine the patho-mechanism of pleural effusion or hydropneumothorax in Mycobacterium avium complex (MAC) lung disease through the computed tomographic (CT) findings.

Materials and Methods

We retrospectively collected data from 5 patients who had pleural fluid samples that were culture-positive for MAC between January 2001 and December 2013. The clinical findings were investigated and the radiological findings on chest CT were reviewed by 2 radiologists.

Results

The 5 patients were all male with a median age of 77 and all had underlying comorbid conditions. Pleural fluid analysis revealed a wide range of white blood cell counts (410–100690/µL). The causative microorganisms were determined as Mycobacterium avium and Mycobacterium intracellulare in 1 and 4 patients, respectively. Radiologically, the peripheral portion of the involved lung demonstrated fibro-bullous changes or cavitary lesions causing lung destruction, reflecting the chronic, insidious nature of MAC lung disease. All patients had broncho-pleural fistulas (BPFs) and pneumothorax was accompanied with pleural effusion.

Conclusion

In patients with underlying MAC lung disease who present with pleural effusion, the presence of BPFs and pleural air on CT imaging are indicative that spread of MAC infection is the cause of the effusion.

Diagnostic performance of measuring antibodies to the glycopeptidolipid core antigen specific to Mycobacterium avium complex in patients with rheumatoid arthritis: results from a cross-sectional observational study

Introduction

The aim of this study was to investigate the diagnostic performance of measuring antibodies to the glycopeptidolipid (GPL) core antigen specific to Mycobacterium avium complex (MAC) in patients with rheumatoid arthritis (RA).

Methods

We cross-sectionally investigated anti-GPL antibodies and radiographs of 396 patients with RA. A diagnosis of MAC pulmonary disease (MAC-PD) was made according to the criteria by the American Thoracic Society and the Infectious Diseases Society of America. Serum immunoglobulin A antibodies to MAC-specific GPL core antigen were measured by an enzyme immunoassay. All patients with RA with abnormal shadows on chest x-rays underwent chest computed tomography (CT). Bronchoscopy was performed on patients with negative cultures for MAC by expectorated sputum and positive CT findings compatible with MAC-PD.

Results

Ten patients were newly diagnosed with MAC-PD. Eight individuals who already had diagnoses of MAC-PD at the time of enrollment and nineteen who had negative expectorated sputum cultures for MAC and positive CT images compatible with MAC-PD and who refused bronchoscopy were excluded from the following analysis. Anti-GPL antibodies were detected in 12 of 369 patients. Eight of the ten patients with MAC-PD and 4 of 359 patients without MAC-PD tested positive for the anti-GPL antibodies. The specificity and sensitivity were 99 % and 80 %, respectively. Positive and negative predictive values were 67 %, and 97 %, respectively. When we analyzed diagnostic performance of the antibodies in 57 patients with RA who had abnormal shadows on chest x-rays, the positive and negative predictive values were 100 %, and 96 %, respectively. Twelve patients underwent bronchoscopy. Bronchoalveolar lavage fluid (BALF) samples from six patients were positive for MAC, and BALF samples from the remainder were negative. Anti-GPL antibodies were detected in the sera of all six patients with positive results for MAC by BALF sampling, whereas the antibodies were not detected in the sera from the remainder with negative results for MAC by BALF sampling.

Conclusions

The measurement of anti-GPL antibodies is useful as a supplementary diagnostic tool for MAC-PD in patients with RA and may provide a new strategy, in combination with chest x-ray and CT, for differentiating MAC-PD from other pulmonary comorbidities in patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0787-y) contains supplementary material, which is available to authorized users.

Newly detected pulmonary nontuberculous mycobacterial infection and peripheral lung cancers in patients during follow-up of idiopathic interstitial pneumonia: comparison of CT findings

This article describes the difference between the computed tomography (CT) findings in patients with newly detected pulmonary nontuberculous mycobacterial infection (NTM-IIP) and Cancer-IIP. We retrospectively evaluated 35 NTM-IIP and 78 Cancer-IIP patients in reference to their null idiopathic interstitial pneumonia CT (n = 113), using >10 years of data. Two independent radiologists analyzed the CT characteristics and the axial location of the main opacity. The interobserver agreement was good (κ > 0.771). The NTM-IIP patients were older (P = 0.034). The median size of the main opacity in the NTM-IIP (27 mm; 11-73) was larger (19 mm; 5-60; P = 0.002). Consolidation (n = 30; 85.7%; odds ratio [OR], 45) and cavities (n = 14; 40%, OR, 25) were more common in NTM-IIP (all P < 0.001). The midst of the fibrotic cysts including honeycomb cysts (n = 16; 45.7%, OR, 4.95) was more common in NTM-IIP (P = 0.006). NTM-IIP appeared larger, with more frequent consolidation and cavities, and was more likely to have been located in the midst of the fibrotic cysts including honeycomb cysts at the CT, which showed that it was older than Cancer-IIP.

Prevalence of nontuberculous mycobacteria in patients with bronchiectasis: a meta-analysis

INTRODUCTION

Nontuberculous mycobacteria (NTM) have emerged as critical opportunistic pathogens of lung diseases recently. Patients with preexisting bronchiectasis are susceptible to NTM. Nevertheless, patients with preexisting bronchiectasis are susceptible to NTM but the prevalence of NTM pulmonary infection in different species and geographical areas is still not fully understood.

MATERIAL AND METHODS

The relevant data of the prevalence of NTM in patients with bronchiectasis were retrieved by searching the main databases such as PubMed, MEDLINE, Cochrane Library, and EMBASE. This meta-analysis was performed using Rev. Man 5.1 and Stata 11.0 software. The collected information of NTM prevalence was chosen as the effect size.

RESULTS

The results of the meta-analysis showed that the overall prevalence of NTM was 9.3% in patients with bronchiectasis. The further stratification of subgroup analysis indicated that the combined prevalence of NTM was higher in studies whose "sample size" was more than or equal to 100 (p = 0.002), in studies in which "time of study" was after or equal to 2002 (p < 0.001), in studies in which "participants' geographic location" was Asian (p < 0.001) and in studies whose "method of study" was retrospective (p = 0.002) as well, compared with corresponding groups.

CONCLUSIONS

Our findings suggested that the prevalence NTM infection is high in patients with bronchiectasis. A larger number of definitive randomized trials are still required to assess this research issue.

Evaluation and management of patients with pulmonary nontuberculous mycobacterial infections

Nontuberculous mycobacteria (NTM) are emerging pathogens increasingly associated with chronic pulmonary disease. NTM are environmental saprophytes found in soil, dust and water and, unlike Mycobacterium tuberculosis, NTM are not transmitted from person to person. Pulmonary disease caused by NTM is a particular problem in older people without underlying immune compromise. The diagnosis of NTM pulmonary disease usually requires either multiple respiratory cultures that grow NTM or heavy growth of NTM from a single bronchoscopy or lung-biopsy specimen. High resolution computed tomography is the most useful radiographic study for diagnosis and to determine the extent of disease. Treatment includes multiple medications with activity against the particular NTM species, as single-drug therapy is likely to select for resistant organisms. Data demonstrating the effectiveness of specific drug regimens for NTM pulmonary disease are limited. Clarithromycin and azithromycin form the backbone of most treatment regimens because these drugs are active against many NTM species. Drug tolerability and cost are the major barriers to successful treatment of NTM pulmonary disease. Adjunctive therapies, including mucus clearance techniques and appetite stimulants, are unproven but may be of value in management of NTM pulmonary disease. Multicenter, randomized trials of macrolide-based therapies are sorely needed to determine the safest and most effective treatments for NTM pulmonary disease.

Occurrence of nontuberculous mycobacterial pulmonary infection in an endemic area of tuberculosis

The majority of investigations of the epidemiology of nontuberculous mycobacteria (NTM) have focused on highly developed nations with a low prevalence of tuberculosis. In contrast, the Para state of north Brazil represents an area of high tuberculosis prevalence and increasing NTM incidence. Toward the goal of understanding the dynamics of infection by all Mycobacterium species, we report patient characteristics and the identification of NTM strains isolated from sputum samples from patients that were residents of Para, a state in the Amazon region, Northern of Brazil, over the period January 2010 through December 2011 (2 years). The 29 NTM patients comprised 13.5% of positive mycobacterial cultures over the 2-year period. A major risk factor for NTM pulmonary disease was previous tuberculosis (76%). Further, the average age of NTM patients (52 years) was significantly higher than that of tuberculosis patients (39 years) and more were female (72.4% vs. 37.4%). Unlike other Brazilian states, NTM pulmonary patients in Para were infected with a different spectrum of mycobacteria; primarily the rapidly growing Mycobacterium massiliense and Mycobacterium simiae complex.

Nontuberculous mycobacteria (NTM) are environmental organisms that are naturally found in soil, water, dust and other sites. Several case reports and studies on the prevalence of pulmonary NTM disease have been published, nevertheless, the impact and the exact magnitude of NTM infections in countries where tuberculosis (TB) is endemic are not known. Here, we report the identification of NTM strains isolated from pulmonary samples from patients with a presumptive diagnosis of pulmonary TB and residents of the State of Para, in the Amazon region, Northern of Brazil. This study documents the occurrence and diversity of species of NTM that cause pulmonary disease in a region representative of those in the world with high infection rates by Mycobacterium tuberculosis.

Non-tuberculous mycobacterial pulmonary infection in the immunocompetent host

Throughout much of the world, the incidence of non-tuberculous mycobacterial pulmonary infections in immunocompetent hosts is on the rise. These organisms are widespread in the natural environment; the explanation for what appears to be an increased susceptibility among human hosts is uncertain. Among more than 120 known species, the most common pathogenic isolate in the USA is Mycobacterium avium complex. The diagnosis of pulmonary disease caused by M. avium complex requires a compatible history, suggestive radiographic findings (on chest computed tomography) and microbiologic confirmation on culture of respiratory samples (sputum or direct lung sampling). Treatment options have improved with inclusion of macrolide antibiotics in a multi-drug regimen, but failure rates remain high (20-40%) even after a prolonged course of therapy. Newer, less toxic and more effective anti-mycobacterial agents are greatly needed for treatment of this increasingly common respiratory disease.

Cavitary pulmonary infection with Mycobacterium avium observed by bronchoscopy

A 58-year-old man was admitted to our hospital because of fever and loss of appetite. He had undergone surgery for esophageal cancer. A chest radiography 12 years after the surgery revealed cavitary lesions in the right upper lobe of the lung. The patient was then diagnosed as having Mycobacterium avium infection. The cavitary lesions worsened 2 years after clarithromycin monotherapy. Bronchoscopy was performed to observe the interior of the cavity. Gray debris adhering to the cavitary wall decreased after intensive treatment with Streptomycin, rifabutin, levofloxacin, and ethambutol. This is a rare case in which treatment efficacy of M. avium infection was directly observed by serial bronchoscopy.

Nontuberculous mycobacteria: opportunistic environmental pathogens for predisposed hosts

Nontuberculous mycobacterial (NTM) infections are caused by environmental mycobacteria. Patients with pulmonary NTM disease usually have predisposing lung abnormalities. Diagnostic methods are evolving. Treatment is largely empiric. Data were extracted from peer reviewed publications, guidelines, and case series. Progressive NTM lung disease should be treated. Multidrug regimens are mostly macrolide based and are occasionally complemented by lung resection. Disease persistence and relapse are not uncommon and are a greater problem with so-called rapid-grower NTM infections. Some of the issues considered in this review are: the role of antibiotic susceptibility testing in predicting treatment effectiveness, optimal drug combinations, daily vs. intermittent dosing intervals for different NTM infections and disease severity, when the goal of cure should be replaced with observation or palliation, and patient selection for surgery. Future needs for development and research include improved epidemiology, definition of genetic and other risk factors, definition of predictors of treatment outcome, multicenter treatment studies, new drug discovery and animal models of disease and treatment.

Non-localized Mycobacterium avium lung disease successfully treated with lobectomy and chemotherapy

A 17-year-old boy presented with a large cavity and bilateral nodular opacities on his chest roentgenogram. Mycobacterium avium was identified in his sputum. According to the recommendations of the American Thoracic Society, he was not strongly recommended to undergo surgery because of non-localized lesions. But since cavities can provide a means for disease to spread to other lobes, we decided to perform a lobectomy including the cavity combined with chemotherapy. Now he has been well for 4 years without exacerbation. There is a possibility of long-term remission with this combination treatment in cases a destructive lesion of airway such as a cavity which is localized to one lobe, even if other lesions such as nodular opacities exist in many other lobes.

The pathophysiology of bronchiectasis

Bronchiectasis is defined by permanent and abnormal widening of the bronchi. This process occurs in the context of chronic airway infection and inflammation. It is usually diagnosed using computed tomography scanning to visualize the larger bronchi. Bronchiectasis is also characterized by mild to moderate airflow obstruction. This review will describe the pathophysiology of noncystic fibrosis bronchiectasis. Studies have demonstrated that the small airways in bronchiectasis are obstructed from an inflammatory infiltrate in the wall. As most of the bronchial tree is composed of small airways, the net effect is obstruction. The bronchial wall is typically thickened by an inflammatory infiltrate of lymphocytes and macrophages which may form lymphoid follicles. It has recently been demonstrated that patients with bronchiectasis have a progressive decline in lung function. There are a large number of etiologic risk factors associated with bronchiectasis. As there is generally a long-term retrospective history, it may be difficult to determine the exact role of such factors in the pathogenesis. Extremes of age and smoking/chronic obstructive pulmonary disease may be important considerations. There are a variety of different pathogens involved in bronchiectasis, but a common finding despite the presence of purulent sputum is failure to identify any pathogenic microorganisms. The bacterial flora appears to change with progression of disease.

HRCT in detection of pulmonary infections from nontuberculous mycobacteria: personal experience

PURPOSE

The authors sought to assess the role of high-resolution computed tomography (HRCT) in the detection and follow-up of nontuberculous mycobacteria (NTM) pulmonary infection in immunocompetent patients and to identify the most common radiological patterns for diagnosis.

MATERIALS AND METHODS

Plain chest radiographs and HRCT scans of 42 consecutive patients with NTM pulmonary infection (M/F 26/16; mean age 57, range 41-83) were retrospectively reviewed. Ten of these patients were followed up for 18 months after diagnosis. Small nodules (<10 mm), nodules 10- to 30-mm in diameter, lobar/segmental consolidation, cavitations, bronchiectasis and tree-in-bud pattern were analysed.

RESULTS

Small nodules were more frequent than nodules 10- to 30-mm in diameter, and segmental consolidation was more frequent than lobar. Cavitations, tree-in-bud and bronchiectasis were more frequently located in the upper lobes. Four of the followed-up patients had cavitation of preexisting nodules, and five had progression of bronchiectasis.

CONCLUSIONS

HRCT allows accurate detection and followup of the most frequent presentation patterns: diffuse small nodules, bronchiectasis, upper lobe segmental consolidation and cavitations. The appearance of new bronchiectasis and progression of old disease are due to pulmonary infection.

Pulmonary nontuberculous mycobacterial disease: prospective study of a distinct preexisting syndrome

RATIONALE

Pulmonary nontuberculous mycobacterial (PNTM) disease is increasing, but predisposing features have been elusive.

OBJECTIVES

To prospectively determine the morphotype, immunophenotype, and cystic fibrosis transmembrane conductance regulator genotype in a large cohort with PNTM.

METHODS

We prospectively enrolled 63 patients with PNTM infection, each of whom had computerized tomography, echocardiogram, pulmonary function, and flow cytometry of peripheral blood. In vitro cytokine production in response to mitogen, LPS, and cytokines was performed. Anthropometric measurements were compared with National Health and Nutrition Examination Survey (NHANES) age- and ethnicity-matched female control subjects extracted from the NHANES 2001-2002 dataset.

MEASUREMENTS AND MAIN RESULTS

Patients were 59.9 (+/-9.8 yr [SD]) old, and 5.4 (+/-7.9 yr) from diagnosis to enrollment. Patients were 95% female, 91% white, and 68% lifetime nonsmokers. A total of 46 were infected with Mycobacterium avium complex, M. xenopi, or M. kansasii; 17 were infected with rapidly growing mycobacteria. Female patients were significantly taller (164.7 vs. 161.0 cm; P < 0.001) and thinner (body mass index, 21.1 vs. 28.2; P < 0.001) than matched NHANES control subjects, and thinner (body mass index, 21.1 vs. 26.8; P = 0.002) than patients with disseminated nontuberculous mycobacterial infection. A total of 51% of patients had scoliosis, 11% pectus excavatum, and 9% mitral valve prolapse, all significantly more than reference populations. Stimulated cytokine production was similar to that of healthy control subjects, including the IFN-gamma/IL-12 pathway. CD4(+), CD8(+), B, and natural killer cell numbers were normal. A total of 36% of patients had mutations in the cystic fibrosis transmembrane conductance regulator gene.

CONCLUSIONS

Patients with PNTM infection are taller and leaner than control subjects, with high rates of scoliosis, pectus excavatum, mitral valve prolapse, and cystic fibrosis transmembrane conductance regulator mutations, but without recognized immune defects.

Cavitary pulmonary disease

A pulmonary cavity is a gas-filled area of the lung in the center of a nodule or area of consolidation and may be clinically observed by use of plain chest radiography or computed tomography. Cavities are present in a wide variety of infectious and noninfectious processes. This review discusses the differential diagnosis of pathological processes associated with lung cavities, focusing on infections associated with lung cavities. The goal is to provide the clinician and clinical microbiologist with an overview of the diseases most commonly associated with lung cavities, with attention to the epidemiology and clinical characteristics of the host.

The Many Faces of Pulmonary Nontuberculous Mycobacterial Infection

OBJECTIVE

The purpose of this article is to review clinical and radiologic manifestations of pulmonary nontuberculous mycobacterial infection.

CONCLUSION

Common and well-recognized patterns of infection include cavitary and bronchiectatic disease and infection in AIDS patients. Less common or well-recognized manifestations include nodules or masses mimicking malignancy, hypersensitivity pneumonitis, and others. Definitive diagnosis can be difficult and patterns may overlap. Timely diagnosis requires a high index of suspicion and knowledge of the spectrum of clinical and radiologic features.

Radiological findings of mycobacterial diseases

The diagnosis and treatment of mycobacterial diseases are very important clinical issues. Among mycobacterial diseases, pulmonary tuberculosis remains an important cause of morbidity and mortality throughout the world. Pulmonary tuberculosis demonstrates a variety of clinical and radiological features. In addition, the prevalence of Mycobacterium avium complex (MAC) has increased, especially in elderly women without underlying diseases. Clinically, there is a significant difference between tuberculosis and atypical mycobacterium infection in terms of the infection control measures adopted and the choice of treatment. Therefore, it is very important to know the characteristic radiological findings of mycobacterial diseases. In the present review, key radiological points for diagnosing mycobacterial diseases are discussed.

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.

Lung Disease Due to the More Common Nontuberculous Mycobacteria

As the prevalence of tuberculosis (TB) declines in the developed world, the proportion of mycobacterial lung disease due to nontuberculous mycobacteria (NTM) is increasing. It is not clear whether there is a real increase in prevalence or whether NTM disease is being recognized more often because of the introduction of more sensitive laboratory techniques, and that more specimens are being submitted for mycobacterial staining and culture as the result of a greater understanding of the role of NTM in conditions such as cystic fibrosis, posttransplantation and other forms of iatrogenic immunosuppression, immune reconstitution inflammatory syndrome, fibronodular bronchiectasis, and hypersensitivity pneumonitis. The introduction of BACTEC liquid culture systems (BD; Franklin Lakes, NJ) and the development of nucleic acid amplification and DNA probes allow more rapid diagnosis of mycobacterial disease and the quicker differentiation of NTM from TB isolates. High-performance liquid chromatography, polymerase chain reaction, and restriction fragment length polymorphism analysis have helped to identify new NTM species. Although treatment regimens that include the newer macrolides are more effective than the earlier regimens, failure rates are still too high and relapse may occur after apparently successful therapy. Moreover, treatment regimens are difficult to adhere to because of their long duration, adverse effects, and interactions with the other medications that these patients require. The purpose of this article is to review the common presentations of NTM lung disease, the conditions associated with NTM lung disease, and the clinical features and treatment of the NTM that most commonly cause lung disease.

Four cases of pulmonary Mycobacterium avium intracellulare complex presenting as a solitary pulmonary nodule and a review of other cases in Japan

OBJECTIVE

To evaluate clinical findings of patients with a solitary pulmonary nodule in Japan caused by pulmonary Mycobacterium avium complex (MAC) disease.

METHODS

The authors investigated the clinical features of 12 patients diagnosed as having pulmonary MAC disease who had presented with a solitary pulmonary nodule.

RESULTS

The causative microorganisms were M. avium in seven patients, Mycobacterium intracellulare in two and MAC in three. The diagnostic methods were bronchoscopic biopsy or percutaneous lung biopsy in three patients and surgical operations in the remaining nine. Eleven patients had a complete surgical resection of the nodule and antituberculous drugs were administered to eight. On X-ray, there was an absence of calcification, satellite lesions, cavities, or bronchoectasis that are often thought to be characteristic of pulmonary mycobacterial disease. Differentiation from lung cancer was thought necessary in five patients. There was no microbiological or radiological relapse in those who underwent complete surgical resection.

CONCLUSIONS

Because treatment is often poorly effective for patients with pulmonary non-tuberculous mycobacterial disease, it is important to identify the causative microorganisms by performing a culture examination of resected lung tissue especially if there is a solitary pulmonary nodule.

Drug-sensitive tuberculosis, multidrug-resistant tuberculosis, and nontuberculous mycobacterial pulmonary disease in nonAIDS adults: comparisons of thin-section CT findings

The aim of this work was to compare thin-section CT (TSCT) findings of drug-sensitive (DS) tuberculosis (TB), multidrug-resistant (MDR) TB, and nontuberculous mycobacterial (NTM) pulmonary disease in nonAIDS adults. During 2003, 216 (113 DS TB, 35 MDR TB, and 68 NTM) patients with smear-positive sputum for acid-fast bacilli (AFB), and who were subsequently confirmed to have mycobacterial pulmonary disease, underwent thoracic TSCT. The frequency of lung lesion patterns on TSCT and patients' demographic data were compared. The commonest TSCT findings were tree-in-bud opacities and nodules. On a per-person basis, significant differences were found in the frequency of multiple cavities and bronchiectasis (P < 0.001, chi-square test and multiple logistic regression analysis). Multiple cavities were more frequent in MDR TB than in the other two groups and extensive bronchiectasis in NTM disease (multiple logistic regression analysis). Patients with MDR TB were younger than those with DS TB or NTM disease (P < 0.001, multiple logistic regression analysis). Previous tuberculosis treatment history was significantly more frequent in patients with MDR TB or NTM disease (P < 0.001, chi-square test and multiple logistic regression analysis). In patients with positive sputum AFB, multiple cavities, young age, and previous tuberculosis treatment history imply MDR TB, whereas extensive bronchiectasis, old age, and previous tuberculosis treatment history NTM disease.

Acute pneumonia and empyema caused by Mycobacterium intracellulare

Nontuberculous mycobacterial infection is rarely accompanied by pleural involvement. We report a very rare case of M. intracellulare pulmonary disease with pleural empyema. A 56-year-old man was admitted to our hospital because of fever, purulent sputum and pleuritic chest pain. A chest radiograph and CT revealed pneumonic consolidation in the left lower lobe and loculated hydropneumothorax. The sputum smear was positive for acid fast bacilli. The aspirated pleural fluid was grossly purulent and the smear of the pleural effusion was also positive for acid fast bacilli. M. intracellulare was identified by culture and PCR from sputum and pleural fluid specimens. The patient improved with percutaneous tube drainage of the purulent effusion and antibiotic treatment including clarithromycin, rifampicin, ethambutol and streptomycin.

Diagnosis and treatment of nontuberculous mycobacterial pulmonary diseases: a Korean perspective

The incidence of pulmonary disease caused by nontuberculous mycobacteria (NTM) appears to be increasing worldwide. In Korea, M. avium complex and M. abscessus account for most of the pathogens encountered, whilst M. kansasii is a relatively uncommon cause of NTM pulmonary diseases. NTM pulmonary disease is highly complex in terms of its clinical presentation and management. Because its clinical features are indistinguishable from those of pulmonary tuberculosis and NTMs are ubiquitous in the environment, the isolation and identification of causative organisms are mandatory for diagnosis, and some specific diagnostic criteria have been proposed. The treatment of NTM pulmonary disease depends on the infecting species, but decisions concerning the institution of treatment are never easy. Treatment requires the use of multiple drugs for 18 to 24 months. Thus, treatment is expensive, often has significant side effects, and is frequently not curative. Therefore, clinicians should be confident that there is sufficient pathology to warrant prolonged, multidrug treatment regimens. In all of the situations, outcomes can be best optimized only when clinicians, radiologists, and laboratories work cooperatively.

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.

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.

Bilateral bronchiectasis and bronchiolitis at thin-section CT: diagnostic implications in nontuberculous mycobacterial pulmonary infection

PURPOSE

To determine frequency of nontuberculous mycobacterial (NTM) pulmonary infection in patients with bilateral bronchiectasis and bronchiolitis at chest computed tomography (CT) and whether CT findings are indicative of Mycobacterium avium-intracellulare complex (MAC) infection.

MATERIALS AND METHODS

Institutional review board approved this research study; patient informed consent (not required) was obtained from all patients to perform CT. From July 2000 to December 2002, 126 consecutive patients, who were suspected of having NTM pulmonary infection at helical CT (120 kVp, 70 mA, 2.5-mm collimation, pitch of 6) with findings of bilateral bronchiectasis and bronchiolitis, were included. Of these, 105 patients underwent study for diagnosis of NTM disease. Medical records and CT scans were reviewed for final diagnoses. Clinical and chest CT findings in patients with NTM disease and those with other airway diseases were compared (unpaired t test, chi(2) test, or Fisher exact test).

RESULTS

NTM pulmonary infection was seen in 36 (34%) of 105 patients; NTM was definite in 32 (30%) and probable in four (4%). In decreasing order of frequency, organisms involved were MAC in 18 patients (50%), with M avium in 10 and M intracellulare in eight, Mycobacterium abscessus in 14 (39%), Mycobacterium kansasii in one (3%), and Mycobacterium fortuitum in one (3%); organisms were unidentifiable in two (6%). Female (P = .031) nonsmokers (P = .037) with history of treatment for Mycobacterium tuberculosis (P = .002), sputum smear positive for acid-fast bacilli (P < .001), and thin-section CT findings of bronchiolitis in more than five lobes with bronchiectasis (P = .011), lobular consolidation (P = .010), and a cavity (P < .001) were related to diagnosis of NTM pulmonary infection.

CONCLUSION

About one-third of patients with thin-section CT findings of bilateral bronchiectasis and bronchiolitis have NTM pulmonary infection; in these situations, MAC and M abscessus are two most frequent causative organisms. Thin-section CT findings of bronchiectasis and bronchiolitis involving more than five lobes, especially when associated with lobular consolidation or a cavity, are highly suggestive of NTM pulmonary infection.

Mycobacterium avium complex pulmonary disease in patients without HIV infection

Mycobacterium avium complex (MAC) is ubiquitous. It is found in various freshwater and saltwater sources around the world, including hot water pipes. Although the organism was identified in the 1890s, its potential to cause human disease was only recognized 50 years later. Only a minority of people exposed to the organism will acquire MAC lung disease, usually those with underlying lung disease or immunosuppression. MAC may, however, cause progressive parenchymal lung disease and bronchiectasis in patients without underlying lung disease, particularly in middle-aged and elderly women. Preliminary data suggest that the interferon-gamma pathways may be deficient in elderly women with MAC lung disease. Other groups of patients who are more likely to harbor MAC in their lungs include patients with a cystic fibrosis or an abnormal alpha(1)-antiproteinase gene and patients with certain chest wall abnormalities. Treatment results continue to be disappointing, and the mortality of patients with MAC lung disease remains high. A PubMed search identified 38 reports of the treatment of MAC lung disease. Apart from the British Thoracic Society study, the only published controlled investigation, the studies published since 1994 have included a macrolide, either clarithromycin or azithromycin, usually in combination with ethambutol and a rifamycin. If success is defined as eradication of the organism without relapse over a period of several years after treatment has been discontinued, the reported treatment success rate with the macrolide containing regimens is approximately 55%. The prolonged treatment period, side effects, and possibly reinfection rather than relapse are responsible for the high failure rate.

Pulmonary Mycobacterium avium disease with a solitary pulmonary nodule requiring differentiation from recurrence of pulmonary adenocarcinoma

A 56-year-old man with a past history of surgical resection of a primary pulmonary adenocarcinoma in the right upper lobe was admitted to our hospital because of a rapidly increasing solitary nodule (50x30 mm) in the right S5 followed on the chest computed tomography (CT) for three months. Although we suspected recurrence of the pulmonary adenocarcinoma and performed a CT-guided lung biopsy, we could not make a definite diagnosis. Therefore, to rule out recurrence of the primary pulmonary adenocarcinoma completely, a partial surgical resection of the right middle lobe was performed and a caseating epitheloid granuloma with acid-fast bacilli was found. As the causative pathogen, Mycobacterium avium complex (MAC) disease should be considered in the differential diagnosis of a rapidly increasing solitary nodule through this peculiar case of pulmonary MAC disease.