Pulmonary illness associated with exposure to Mycobacterium-avium complex in hot tub water. Hypersensitivity pneumonitis or infection?

[Diagnosis and Treatment of Hypersensitivity Pneumonitis - S2k Guideline of the German Respiratory Society and the German Society for Allergology and Clinical Immunology]

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) in sensitized individuals caused by a large variety of inhaled antigens. The clinical form of acute HP is often misdiagnosed, while the chronic form, especially the chronic fibrotic HP, is difficult to differentiate from other fibrotic ILDs. The present guideline for the diagnosis and treatment of HP replaces the former German recommendations for the diagnosis of HP from 2007 and is amended explicitly by the issue of the chronic fibrotic form, as well as by treatment recommendations for the first time. The evidence was discussed by a multidisciplinary committee of experts. Then, recommendations were formulated for twelve questions on important issues of diagnosis and treatment strategies. Recently published national and international guidelines for ILDs and HP were considered. Detailed background information on HP is useful for a deeper insight into HP and the handling of the guideline.

Water-to-Air Transfer of Nano/Microsized Particulates: Enrichment Effect in Bubble Bursting Jet Drops

Bubbles dispersed in liquids are widely present in many natural and industrial processes and play a key role in mediating mass transfer during their lifetime from formation to rising to bursting. In particular, nano/microsized particulates and organisms present in the bulk water can be highly enriched in the jet drops ejected during bubble bursting, impacting global climate and public health. However, the detailed mechanism of this enrichment remains obscure with the enrichment factor being difficult to predict. Here, we experimentally investigate the enrichment of nano/microsized particles in bubble bursting jet drops and highlight the underlying hydrodynamic mechanism, combining the effects of bubble scavenge and bursting on the transport of particles. Scaling laws for the enrichment factor are subsequently proposed that describe both our and prior experimental results reasonably well. Our study may provide new insights for water-to-air transfer of bulk particulates such as microbes related to bubble bursting.

Identification of nontuberculous mycobacteria isolated from household showerheads of patients with nontuberculous mycobacteria

This study aimed to examine whether nontuberculous mycobacteria (NTM) inside household showerheads are identical to those in patients with NTM-pulmonary disease (PD) since household water is one of the potential NTM sources. Samples were obtained from 32 household showerheads of patients with NTM-PD recruited through the Pulmonary Outpatient Department at the Severance Hospital between October 2018 and October 2019. All isolates from patients with NTM-PD were diagnosed using a reverse-hybridization line probe assay based on the ropB gene. To determine the mycobacterial compositions, the washing fluids were collected and investigated using multiplex polymerase chain reaction assay and NTM culture; suspected microbial isolates in these fluids and culture were identified using sequencing analysis of 16S rRNA gene. NTM species causing the PD in the patients were Mycobacterium avium, M. intracellulare, M. abscessus, M. massiliense, and M. fortuitum complex. The mycobacteria isolated from the showerhead were M. lentiflavum, M. gordonae, M. triplex, M. phocaicum, M. mucogenicum, M. florentinum, M. gilvum, M. llatzerense, and M. peregrinum. However, the species identified in the showerheads did not match those of the patients. Despite NTM species in the showerheads, clinical implications in the main pathogenesis associated with the disease in the patients studied were not elucidated.

Combined obstructive airflow limitation associated with interstitial lung diseases (O-ILD): the bad phenotype ?

BACKGROUND

Patients suffering from combined obstructive and interstitial lung disease (O-ILD) represent a pathological entity which still has to be well clinically described. The aim of this descriptive and explorative study was to describe the phenotype and functional characteristics of a cohort of patients suffering from functional obstruction in a population of ILD patients in order to raise the need of dedicated prospective observational studies and the evaluation of the impact of anti-fibrotic therapies.

METHODS

The current authors conducted a retrospective study including 557 ILD patients, with either obstructive (O-ILD, n = 82) or non-obstructive (non O-ILD, n = 475) pattern. Patients included were mainly males (54%) with a mean age of 62 years.

RESULTS

Patients with O-ILD exhibited a characteristic functional profile with reduced percent predicted forced expired volume in 1 s (FEV1) [65% (53-77) vs 83% (71-96), p < 0.00001], small airway involvement assessed by maximum expiratory flow (MEF) 25/75 [29% (20-41) vs 81% (64-108), p < 0.00001], reduced sGaw [60% (42-75) vs 87% (59-119), p < 0.01] and sub-normal functional residual capacity (FRC) [113% (93-134) vs 92% (75-109), p < 0.00001] with no impaired of carbon monoxide diffusing capacity of the lung (DLCO) compared to those without obstruction. Total lung capacity (TLC) was increased in O-ILD patients [93% (82-107) vs 79% (69-91), p < 0.00001]. Of interest, DLCO sharply dropped in O-ILD patients over a 5-year follow-up. We did not identify a significant increase in mortality in patients with O-ILD. Interestingly, the global mortality was increased in the specific sub-group of patients with O-ILD and no progressive fibrosing ILD phenotype and in those with connective tissue disease associated ILD especially in case of rheumatoid arthritis.

CONCLUSIONS

The authors individualized a specific functional-based pattern of ILD patients with obstructive lung disease, who are at risk of increased mortality and rapid DLCO decline over time. As classically those patients are excluded from clinical trials, a dedicated prospective study would be of interest in order to define more precisely treatment response of those patients.

Exploring the Bacterial Communities of the Kaiafas Thermal Spring Anigrides Nymphes in Greece Prior to Rehabilitation Actions

Anigrides Nymphes of Lake Kaiafas is a thermal spring that is well known for its therapeutical properties, as the hot water (32-34 °C) is rich in sulfur compounds and minerals. Nowadays, efforts are made from the Hellenic Republic to modernize the existing facilities and infrastructure networks of the area. To study the complex ecosystem of the thermal spring, we collected water from four sampling points (Lake, and Caves 1, 2, and 3). Filtration method was used for microbial enumeration. In parallel, total bacterial DNA was extracted and subjected to next-generation sequencing (NGS). A total of 166 different bacterial families were detected. Differences in families, genera, and species abundances were detected between the different sampling points. Specifically, Comamonadaceae was the most common family detected in Lake and Cave 3. Similarly, in Caves 1 and 2, Rhodobacteraceae was detected at a higher percentage compared to the rest of the families. Moreover, the detection of sequences assigned to waterborne or opportunistic pathogens, i.e., Enterobacteriaceae, Legionellaceae, Coxiellaceae, and Clostridiaceae, as well as Enterococcus and Vibrio, is of great importance. Although the presence of pathogens was not examined by quantitative PCR, the detection of their sequences strengthens the need of the planned rehabilitation actions of this natural environment in order to allow human swimming.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex syndrome caused by the inhalation of a variety of antigens in susceptible and sensitized individuals. These antigens are found in the environment, mostly derived from bird proteins and fungi. The prevalence and incidence of HP vary widely depending on the intensity of exposure, the geographical area and the local climate. Immunopathologically, HP is characterized by an exaggerated humoral and cellular immune response affecting the small airways and lung parenchyma. A complex interplay of genetic, host and environmental factors underlies the development and progression of HP. HP can be classified into acute, chronic non-fibrotic and chronic fibrotic forms. Acute HP results from intermittent, high-level exposure to the inducing antigen, usually within a few hours of exposure, whereas chronic HP mostly originates from long-term, low-level exposure (usually to birds or moulds in the home), is not easy to define in terms of time, and may occur within weeks, months or even years of exposure. Some patients with fibrotic HP may evolve to a progressive phenotype, even with complete exposure avoidance. Diagnosis is based on an accurate exposure history, clinical presentation, characteristic high-resolution CT findings, specific IgG antibodies to the offending antigen, bronchoalveolar lavage and pathological features. Complete antigen avoidance is the mainstay of treatment. The pharmacotherapy of chronic HP consists of immunosuppressive drugs such as corticosteroids, with antifibrotic therapy being a potential therapy for patients with progressive disease.

Stability of big surface bubbles: impact of evaporation and bubble size

Surface bubbles have attracted much interest in the past few decades. In this article, we aim to explore the lifetime and thinning dynamics of centimetric surface bubbles. We study the impact of the bubble size as well as that of the atmospheric humidity through a careful control and systematic variation of the relative humidity in the measuring chamber. We first address the question of the drainage under saturated water vapor conditions and show that a model including both capillary and gravity driven drainage provides the best prediction for this process. Additionally, unprecedented statistics on the bubble lifetimes confirm experimentally that this parameter is set by evaporation to leading order. We make use of a model based on the overall thinning dynamics of the thin film and assume a rupture thickness of the order 10-100 nm to obtain a good representation of these data. For experiments conducted far from saturation, the convective evaporation of the bath is shown to dominate the overall mass loss in the cap film due to evaporation.

Infectious Lung Disease

Infectious diseases are one of the main causes of morbidity and mortality worldwide. With new pathogens continuously emerging, known infectious diseases reemerging, increasing microbial resistance to antimicrobial agents, global environmental change, ease of world travel, and an increasing immunosuppressed population, recognition of infectious diseases plays an ever-important role in surgical pathology. This becomes particularly significant in cases where infectious disease is not suspected clinically and the initial diagnostic workup fails to include samples for culture. As such, it is not uncommon that a lung biopsy becomes the only material available in the diagnostic process of an infectious disease. Once the infectious nature of the pathological process is established, careful search for the causative agent is advised. This can often be achieved by examination of the hematoxylin and eosin-stained sections alone as many organisms or their cytopathic effects are visible on routine staining. However, ancillary studies such as histochemical stains, immunohistochemistry, in situ hybridization, or molecular techniques may be needed to identify the organism in tissue sections or for further characterization, such as speciation.

[Hypersensitivity pneumonitis in children]

Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by an immune response to a variety of antigens to which patients have been previously sensitised. It can occur at any age. In children, it is a rare disease, probably under-diagnosed, with an estimated prevalence of 4 per million. The paediatric forms are not really different from those of adults but present some particularities. Avian exposure is by far the most frequent cause of HP, accounting for nearly two-thirds of cases. Although there is no current recommendation for the diagnosis of HP, it is commonly considered that the diagnosis can be made with confidence on the combination of (1) compatible respiratory symptoms, (2) exposure to a known offending antigen, (3) lymphocytic alveolitis, (4) decreased transfer factor for carbon monoxide or hypoxia on exertion and (5) compatible radiologic features. The treatment is based on antigen avoidance that must be complete and definitive. Corticosteroids can be necessary in severe forms. The prognosis of HP in children is better than in adults, with a full clinical and functional recovery in the majority of cases after complete antigenic withdrawal.

Biosurfactants Change the Thinning of Contaminated Bubbles at Bacteria-Laden Water Interfaces

Bubbles reside at the water surface before bursting, emitting droplets that can contain chemicals and pathogens linked to disease and contamination. We discover that bacterial secretions enhance the lifetime of bubbles. We also reveal and elucidate two distinct regimes of thinning for such contaminated bubbles. Initially, marginal regeneration governs their thinning rate, similarly to clean water bubbles. However, due to their enhanced lifetime, it is eventually evaporation that governs their thinning, thus also dramatically decreasing their thickness at burst. We derive and experimentally validate the expression for the critical timescale at which the transition between the two regimes occurs. The shift in thinning law makes the droplets produced by contaminated bubbles smaller, faster, and more numerous than those produced by clean bubbles. Our findings suggest that microorganisms can manipulate the aging physics of surface bubbles to enhance their own water-to-air dispersal.

Global Environmental Nontuberculous Mycobacteria and Their Contemporaneous Man-Made and Natural Niches

Seminal microbiological work of environmental nontuberculous mycobacteria (NTM) includes the discovery that NTM inhabit water distribution systems and soil, and that the species of NTM found are geographically diverse. It is likely that patients acquire their infections from repeated exposures to their environments, based on the well-accepted paradigm that water and soil bioaerosols - enriched for NTM - can be inhaled into the lungs. Support comes from reports demonstrating NTM isolated from the lungs of patients are genetically identical to NTM found in their environment. Well documented sources of NTM include peat-rich soils, natural waters, drinking water, hot water heaters, refrigerator taps, catheters, and environmental amoeba. However, NTM have also been recovered in biofilms from ice machines, heated nebulizers, and heater-cooler units, as well as seat dust from theaters, vacuum cleaners, and cobwebs. New studies on the horizon aim to significantly expand the current knowledge of environmental NTM niches in order to improve our current understanding of the specific ecological factors driving the emergence of NTM lung disease. Specifically, the Hawaiian Island environment is currently being studied as a model to identify other point sources of exposure as it is the U.S. state with the highest number of NTM lung disease cases. Because of its geographic isolation and unique ecosystem, the Hawaiian environment is being probed for correlative factors that may promote environmental NTM colonization.

Mycobacterium avium Complex Disease

Despite the ubiqitous nature of Mycobacterium avium complex (MAC) organisms in the environment, relatively few of those who are infected develop disease. Thus, some degree of susceptibility due to either underlying lung disease or immunosuppression is required. The frequency of pulmonary MAC disease is increasing in many areas, and the exact reasons are unknown. Isolation of MAC from a respiratory specimen does not necessarily mean that treatment is required, as the decision to treatment requires the synthesis of clinical, radiographic, and microbiologic information as well as a weighing of the risks and benefits for the individual patient. Successful treatment requires a multipronged approach that includes antibiotics, aggressive pulmonary hygiene, and sometimes resection of the diseased lung. A combination of azithromycin, rifampin, and ethambutol administered three times weekly is recommend for nodular bronchiectatic disease, whereas the same regimen may be used for cavitary disease but administered daily and often with inclusion of a parenteral aminoglycoside. Disseminated MAC (DMAC) is almost exclusively seen in patients with late-stage AIDS and can be treated with a macrolide in combination with ethambutol, with or without rifabutin: the most important intervention in this setting is to gain HIV control with the use of potent antiretroviral therapy. Treatment outcomes for many patients with MAC disease remain suboptimal, so new drugs and treatment regimens are greatly needed. Given the high rate of reinfection after cure, one of the greatest needs is a better understanding of where infection occurs and how this can be prevented.

Dose response models and a quantitative microbial risk assessment framework for the Mycobacterium avium complex that account for recent developments in molecular biology, taxonomy, and epidemiology

Mycobacterium avium complex (MAC) is a group of environmentally-transmitted pathogens of great public health importance. This group is known to be harbored, amplified, and selected for more human-virulent characteristics by amoeba species in aquatic biofilms. However, a quantitative microbial risk assessment (QMRA) has not been performed due to the lack of dose response models resulting from significant heterogeneity within even a single species or subspecies of MAC, as well as the range of human susceptibilities to mycobacterial disease. The primary human-relevant species and subspecies responsible for the majority of the human disease burden and present in drinking water, biofilms, and soil are M. avium subsp. hominissuis, M. intracellulare, and M. chimaera. A critical review of the published literature identified important health endpoints, exposure routes, and susceptible populations for MAC risk assessment. In addition, data sets for quantitative dose-response functions were extracted from published in vivo animal dosing experiments. As a result, seven new exponential dose response models for human-relevant species of MAC with endpoints of lung lesions, death, disseminated infection, liver infection, and lymph node lesions are proposed. Although current physical and biochemical tests used in clinical settings do not differentiate between M. avium and M. intracellulare, differentiating between environmental species and subspecies of the MAC can aid in the assessment of health risks and control of MAC sources. A framework is proposed for incorporating the proposed dose response models into susceptible population- and exposure route-specific QMRA models.

[Cutaneous lesions during hot-tub hypersensitivity pneumonitis: Pseudomonas folliculitis ?]

BACKGROUND

Interstitial lung disease, cutaneous rash and elevated serum angiotensin converting enzyme (ACE) may suggest diagnoses other than sarcoidosis.

PATIENTS AND METHODS

A 58-year-old man had presented dyspnoea for 2 years with increased angiotensin-converting enzyme, as well as an interstitial syndrome and micronodules. The possibility of sarcoidosis was raised. Systemic corticosteroids resulted in improvement of the dyspnoea although it recurred on dose reduction. We noted fluctuating eczematous macules of the limbs with a histology of aspecific folliculitis. The identification of Mycobacterium avium complex (MAC) in the bronchoalveolar wash prompted us to initiate antimycobacterial therapy, but this was to no avail. Review of the CT-scan and questioning of the patient (daily use of a Jacuzzi for 7 years) resulted in diagnosis of hypersensitivity pneumonitis due to MAC. The cutaneous lesions were taken to indicate "hot tub folliculitis". Discontinuation of hot-tub use and a short course of oral corticosteroids resulted in healing within 4 months, with no recurrence at 2 years.

DISCUSSION

HTL is a form of hypersensitivity pneumonitis due to the presence of MAC in the water of Jacuzzis. This condition regresses spontaneously without treatment on discontinuation of Jacuzzi use. Hot-tub folliculitis due to Pseudomonas aeruginosa (PA) presents as macules and papules on covered skin areas (swimsuit) within 48hours of bathing and often declines within 2 weeks.

CONCLUSION

Our case is original as regards the concomitant lung and cutaneous involvement associated with Jacuzzi use, with an immunoallergic mechanism for the MAC and probably an infectious mechanism for the PA.

Avian Mycobacteriosis: Still Existing Threat to Humans

The nontuberculous mycobacteria are typically environmental organisms residing in soil and water. These microorganisms can cause a wide range of clinical diseases; pulmonary disease is most frequent, followed by lymphadenitis in children, skin and soft tissue disease, and rare extra pulmonary or disseminated infections. Mycobacterium avium complex is the second most common cause of pulmonary mycobacterioses after M. tuberculosis. This review covers the clinical and laboratory diagnosis of infection caused by the members of this complex and particularities for the treatment of different disease types and patient populations.

Pulmonary Disease Due to Nontuberculous Mycobacteria: Current State and New Insights

Since pulmonary nontuberculous mycobacteria (PNTM) lung disease was last reviewed in CHEST in 2008, new information has emerged spanning multiple domains, including epidemiology, transmission and pathogenesis, clinical presentation, diagnosis, and treatment. The overall prevalence of PNTM is increasing, and in the United States, areas of highest prevalence are clustered in distinct geographic locations with common environmental and socioeconomic factors. Although the accepted paradigm for transmission continues to be inhalation from the environment, provocative reports suggest that person-to-person transmission may occur. A panoply of host factors have been investigated in an effort to elucidate why infection from this bacteria develops in ostensibly immunocompetent patients, and there has been clarification that immunocompetent patients exhibit different histopathology from immunocompromised patients with nontuberculous mycobacteria infection. It is now evident that Mycobacterium abscessus, an increasingly prevalent cause of PNTM lung disease, can be classified into three separate subspecies with differing genetic susceptibility or resistance to macrolides. Recent publications also raise the possibility of improved control of PNTM through enhanced adherence to current treatment guidelines as well as new approaches to treatment and even prevention. These and other recent developments and insights that may inform our approach to PNTM lung disease are reviewed and discussed.

A case of familial hot tub lung

Hot tub lung is a lung disease caused by Mycobacterium avium complex. We report the first case of familial hot tub lung appearing simultaneously in a husband and wife. Our case supports the consideration that hot tub lung is a hypersensitivity pneumonitis rather than an infectious lung disease. It also suggests that the state of hot tub lung changes seasonally depending on temperature variations, in a manner similar to summer-type hypersensitivity pneumonitis. This case demonstrates similarities between hot tub lung and summer-type hypersensitivity pneumonitis in regards to familial occurrence and seasonal changes in the disease state.

Host-microbe interactions in distal airways: relevance to chronic airway diseases

This article is the summary of a workshop, which took place in November 2013, on the roles of microorganisms in chronic respiratory diseases. Until recently, it was assumed that lower airways were sterile in healthy individuals. However, it has long been acknowledged that microorganisms could be identified in distal airway secretions from patients with various respiratory diseases, including cystic fibrosis (CF) and non-CF bronchiectasis, chronic obstructive pulmonary disease, asthma and other chronic airway diseases (e.g. post-transplantation bronchiolitis obliterans). These microorganisms were sometimes considered as infectious agents that triggered host immune responses and contributed to disease onset and/or progression; alternatively, microorganisms were often considered as colonisers, which were considered unlikely to play roles in disease pathophysiology. These concepts were developed at a time when the identification of microorganisms relied on culture-based methods. Importantly, the majority of microorganisms cannot be cultured using conventional methods, and the use of novel culture-independent methods that rely on the identification of microorganism genomes has revealed that healthy distal airways display a complex flora called the airway microbiota. The present article reviews some aspects of current literature on host–microbe (mostly bacteria and viruses) interactions in healthy and diseased airways, with a special focus on distal airways.

Understanding host–microbe interactions in distal airways may lead to novel therapies for chronic airway diseaseshttp://ow.ly/HfENz

Review: Environmental mycobacteria as a cause of human infection

Pulmonary infections with nontuberculous mycobacteria (NTM) are recognized as a problem in immunodeficient individuals and are increasingly common in older people with no known immune defects. NTM are found in soil and water, but factors influencing transmission from the environment to humans are mostly unknown. Studies of the epidemiology of NTM disease have matched some clinical isolates of NTM with isolates from the patient's local environment. Definitive matching requires strain level differentiation based on molecular analyses, including partial sequencing, PCR-restriction fragment length polymorphism (RFLP) analysis, random amplified polymorphic DNA (RAPD) PCR, repetitive element (rep-) PCR and pulsed field gel electrophoresis (PFGE) of large restriction fragments. These approaches have identified hospital and residential showers and faucets, hot-tubs and garden soil as sources of transmissible pathogenic NTM. However, gaps exist in the literature, with many clinical isolates remaining unidentified within environments that have been tested, and few studies investigating NTM transmission in developing countries. To understand the environmental reservoirs and transmission routes of pathogenic NTM, different environments, countries and climates must be investigated.

A unique case of hot tub lung worsening during the winter

Summer-type hypersensitivity pneumonitis includes a spectrum of granulomatous lung diseases that result from the inhalation of Trichosporon species in the summer. Hot tub lung is a granulomatous lung disease caused by the inhalation of water aerosols containing non-tuberculous mycobacteria. We herein describe a case of hot tub lung that deteriorated during the winter season. Every winter, the patient's symptoms, laboratory findings and chest images worsened. Genetically identical Mycobacterium avium strains were detected in his sputum and bathtub. The circulation of bathtub water during the winter months only exacerbated his symptoms in the winter.

Evaluation of intraspecies interactions in biofilm formation by Methylobacterium species isolated from pink-pigmented household biofilms

Concern regarding household biofilms has grown due to their widespread existence and potential to threaten human health by serving as pathogen reservoirs. Previous studies identified Methylobacterium as one of the dominant genera found in household biofilms. In the present study, we examined the mechanisms underlying biofilm formation by using the bacterial consortium found in household pink slime. A clone library analysis revealed that Methylobacterium was the predominant genus in household pink slime. In addition, 16 out of 21 pink-pigmented bacterial isolates were assigned to the genus Methylobacterium. Although all of the Methylobacterium isolates formed low-level biofilms, the amount of the biofilms formed by Methylobacterium sp. P-1M and P-18S was significantly increased by co-culturing with other Methylobacterium strains that belonged to a specific phylogenetic group. The single-species biofilm was easily washed from the glass surface, whereas the dual-species biofilm strongly adhered after washing. A confocal laser scanning microscopy analysis showed that the dual-species biofilms were significantly thicker and tighter than the single-species biofilms.

Moving with bubbles: a review of the interactions between bubbles and the microorganisms that surround them

Bubbles are ubiquitous in biological environments, emerging during the complex dynamics of waves breaking in the open oceans or being intentionally formed in bioreactors. From formation, through motion, until death, bubbles play a critical role in the oxygenation and mixing of natural and artificial ecosystems. However, their life is also greatly influenced by the environments in which they emerge. This interaction between bubbles and microorganisms is a subtle affair in which surface tension plays a critical role. Indeed, it shapes the role of bubbles in mixing or oxygenating microorganisms, but also determines how microorganisms affect every stage of the bubble's life. In this review, we guide the reader through the life of a bubble from birth to death, with particular attention to the microorganism-bubble interaction as viewed through the lens of fluid dynamics.

Bacterial pathogens

Bacterial infections are frequent complications among patients treated for cancer. The type, severity, and treatment of bacterial infections vary and depend upon the specific malignancy, associated chemotherapies, and transplantation. This chapter discusses commonly encountered bacterial pathogens as well as Nocardia and mycobacteria in patients with cancer and addresses the clinical syndromes and management. Drug-resistant bacteria are becoming an increasingly recognized problem in patients with cancer. Antimicrobial resistance in select gram-positive and gram-negative bacteria are discussed along with the mechanisms of resistance and recommended therapies.

Proposed definitions for epidemiologic and clinical studies of Mycobacterium avium complex pulmonary disease

Background

Epidemiologic and clinical studies of Mycobacterium avium complex (MAC) pulmonary disease typically use strict ATS/IDSA definitions designed for decisions about treatment. Studies based on these criteria may exclude a substantial number of patients with true disease. We reviewed patients treated for MAC pulmonary disease at an academic medical center to propose revised definitions encompass the full spectrum of MAC pulmonary disease.

Methods

We conducted a retrospective review of patients with MAC pulmonary disease treated from 1993–2006 by pulmonary or infectious disease specialists to assess whether treated patients met current ATS/IDSA microbiologic criteria and dichotomous radiologic classification as nodular/bronchiectatic (NB) or fibrocavitary (FC) disease. We propose a revised set of definitions that include categories of both probable and definite disease to include all treated patients. We further classify patients into dichotomous clinical categories as: “primary MAC” (without antecedent lung disease) or “secondary MAC” (smoking history or antecedent lung disease).

Results

Among 72 treated patients, 74% were female. Median age at diagnosis was 64 years; 41(57%) met ATS/IDSA criteria and 31 (43%) did not, most often for lack of multiple positive cultures. Dichotomous radiologic criteria were met by 48 (67%) patients (36 NB, 12 FC); the remaining 24 (33%) had both NB and FC findings or other abnormalities. Nineteen (26%) were classified as primary and 53 (74%) as secondary MAC (21 COPD, 4 bronchiectasis, 44 smoking history).

Conclusions

We propose revised definitions for epidemiologic and clinical studies of MAC pulmonary disease that describe the full spectrum of disease.

Mycobacteria in Finnish cooling tower waters

Evaporative cooling towers are water systems used in, e.g., industry and telecommunication to remove excess heat by evaporation of water. Temperatures of cooling waters are usually optimal for mesophilic microbial growth and cooling towers may liberate massive amounts of bacterial aerosols. Outbreaks of legionellosis associated with cooling towers have been known since the 1980's, but occurrences of other potentially pathogenic bacteria in cooling waters are mostly unknown. We examined the occurrence of mycobacteria, which are common bacteria in different water systems and may cause pulmonary and other soft tissue infections, in cooling waters containing different numbers of legionellae. Mycobacteria were isolated from all twelve cooling systems and from 92% of the 24 samples studied. Their numbers in the positive samples varied from 10 to 7.3 × 10(4) cfu/L. The isolated species included M. chelonae/abscessus, M. fortuitum, M. mucogenicum, M. peregrinum, M. intracellulare, M. lentiflavum, M. avium/nebraskense/scrofulaceum and many non-pathogenic species. The numbers of mycobacteria correlated negatively with the numbers of legionellae and the concentration of copper. The results show that cooling towers are suitable environments for potentially pathogenic mycobacteria. Further transmission of mycobacteria from the towers to the environment needs examination.

Hypersensitivity pneumonitis: a review and update of histologic findings

Hypersensitivity pneumonitis (HSP) is a poorly understood entity typically caused by exposure to an inciting antigen such as fungi, thermophilic bacteria or animal protein. Clinically, HSP is often divided into acute, subacute and chronic forms. While the subacute form is best described from a pathologic standpoint, the pathology of chronic HSP has only been critically evaluated in the past decade and the pathology of acute HSP is poorly described. The aim of this review is to summarise the current knowledge of pathogenetic theories of HSP and to review the current knowledge of the pathology of each stage of HSP and the main entities in the differential diagnosis.

Isolation of nontuberculous mycobacteria (NTM) from household water and shower aerosols in patients with pulmonary disease caused by NTM

It has been postulated that susceptible individuals may acquire infection with nontuberculous mycobacteria (NTM) from water and aerosol exposure. This study examined household water and shower aerosols of patients with NTM pulmonary disease. The mycobacteria isolated from clinical samples from 20 patients included M. avium (5 patients), M. intracellulare (12 patients), M. abscessus (7 patients), M. gordonae (1 patient), M. lentiflavum (1 patient), M. fortuitum (1 patient), M. peregrinum (1 patient), M. chelonae (1 patient), M. triplex (1 patient), and M. kansasii (1 patient). One-liter water samples and swabs were collected from all taps, and swimming pools or rainwater tanks. Shower aerosols were sampled using Andersen six-stage cascade impactors. For a subgroup of patients, real-time PCR was performed and high-resolution melt profiles were compared to those of ATCC control strains. Pathogenic mycobacteria were isolated from 19 homes. Species identified in the home matched that found in the patient in seven (35%) cases: M. abscessus (3 cases), M. avium (1 case), M. gordonae (1 case), M. lentiflavum (1 case), and M. kansasii (1 case). In an additional patient with M. abscessus infection, this species was isolated from potable water supplying her home. NTM grown from aerosols included M. abscessus (3 homes), M. gordonae (2 homes), M. kansasii (1 home), M. fortuitum complex (4 homes), M. mucogenicum (1 home), and M. wolinskyi (1 home). NTM causing human disease can be isolated from household water and aerosols. The evidence appears strongest for M. avium, M. kansasii, M. lentiflavum, and M. abscessus. Despite a predominance of disease due to M. intracellulare, we found no evidence for acquisition of infection from household water for this species.

Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria

Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria.

Mycobacterium avium complex--the role of potable water in disease transmission

Mycobacterium avium complex (MAC) is a group of opportunistic pathogens of major public health concern. It is responsible for a wide spectrum of disease dependent on subspecies, route of infection and patients pre-existing conditions. Presently, there is limited research on the incidence of MAC infection that considers both pulmonary and other clinical manifestations. MAC has been isolated from various terrestrial and aquatic environments including natural waters, engineered water systems and soils. Identifying the specific environmental sources responsible for human infection is essential in minimizing disease prevalence. This paper reviews current literature and case studies regarding the wide spectrum of disease caused by MAC and the role of potable water in disease transmission. Potable water was recognized as a putative pathway for MAC infection. Contaminated potable water sources associated with human infection included warm water distribution systems, showers, faucets, household drinking water, swimming pools and hot tub spas. MAC can maintain long-term contamination of potable water sources through its high resistance to disinfectants, association with biofilms and intracellular parasitism of free-living protozoa. Further research is required to investigate the efficiency of water treatment processes against MAC and into construction and maintenance of warm water distribution systems and the role they play in MAC proliferation.

Hypersensitivity pneumonia: the role of lung biopsy in diagnosis and management

Hypersensitivity pneumonia is a form of diffuse interstitial lung disease resulting from sensitization to an inhaled antigen. Clinical and radiological features are relatively nonspecific, overlapping significantly with other forms of diffuse interstitial lung disease. Establishing the diagnosis in the absence of lung biopsy is challenging and is heavily dependent on being able to identify a specific antigenic exposure. Lung biopsy is especially important in diagnosing hypersensitivity pneumonia in patients for whom no incriminating exposure has been elucidated. Surgical lung biopsies show a classical combination of findings in the majority of patients, which include an airway-centered, variably cellular chronic interstitial pneumonia, a lymphocyte-rich chronic bronchiolitis, and poorly formed non-necrotizing granulomas distributed mainly within the peribronchiolar interstitium. The bronchiolitis may include variable degrees of peribronchiolar fibrosis and hyperplasia of the bronchiolar epithelium ('peribronchiolar metaplasia'), a characteristic but a nonspecific finding. In some patients, granulomatous inflammation may be lacking, resulting in a histological appearance resembling nonspecific interstitial pneumonia. Late-stage fibrotic hypersensitivity pneumonia results in clinical, radiological, and histological findings that closely mimic usual interstitial pneumonia. The presence of established collagen fibrosis, especially when associated with architectural distortion in the form of honeycomb change, is associated with shorter survivals.

[Diagnosis and treatment of atypical mycobacterial infections of the respiratory tract]

INTRODUCTION

Non tuberculous mycobacteria (NTM), unlike tuberculous mycobacteria, are not strictly human pathogens. The diagnosis of infection and the choice of treatment remain difficult.

BACKGROUND

Evidence of a NTM in a pulmonary sample is not synonymous with infection. The diagnosis depends on the association of clinical, radiological and microbiological factors. If a NTM is isolated from a respiratory sample, the probability of infection depends on the species. The main NTMs responsible for pulmonary infection in France are Mycobacterium avium intracellulare, Mycobacterium xenopi, Mycobacterium kansasi and Mycobacterium abscessus. Their management is difficult and poorly understood. Treatment is well established for M. avium intracellulare and M. kansasii, with combinations of clarithromycin-rifampicin-ethambutol and isoniazid-rifampicin-ethambutol respectively. For M. xenopi, the optimal treatment is not known and a combination of clarithromycin-rifampicin-ethambutol, with moxifloxacin as an alternative, is currently recommended. In general, treatment is prolonged and often associated with problems of tolerance.

VIEWPOINT AND CONCLUSION

The management of NTM infection, taking into account of the increase in patients "at risk", is an important issue. Further studies are needed to improve the criteria for infection and to find the optimal therapeutic combinations.

Frequency, treatment, and functional outcome in children with hypersensitivity pneumonitis

BACKGROUND

Hypersensitivity pneumonitis is a rare interstitial lung disease and very few data regarding frequency, treatment and outcome exist for children. Children identified with hypersensitivity pneumonia from a Danish national cohort with diffuse interstitial lung disease form the basis of this study focused on disease frequency, treatment, and functional outcome.

METHODS

Seventy-three children with clinical and radiological signs of interstitial lung disease verified by lung biopsy were identified over a 12-year period. Histologic material from all cases was reviewed by pathologists from the ChILD Clinical and Research Network, USA. Diagnosis of hypersensitivity pneumonitis was confirmed in 19 cases.

MEASUREMENTS AND MAIN RESULTS

Incidence of hypersensitivity pneumonitis was approximately 2/year and with a point prevalence of 4/1,000,000 children. The median (range) number of monthly courses with intravenous methylprednisolone was 15 courses (8-34) in resolved cases, but in the vast majority (92%), mono-therapy with high dose pulse methylprednisolone treatment was not sufficient for acceptable improvement. Lung function, DLco and DLco/VA increased significantly after 3 and 6 months of treatment compared to baseline (P < 0.05). However, without reaching normal values [mean SDS (range) FEV(1) -0.66 (-1.88 to 0.41) and FVC -0.67(-1.94 to 0)]. No mortality was seen.

CONCLUSIONS

Incidence and point prevalence of hypersensitivity pneumonitis in Denmark was 2/year and 4/1.000.000 children. High dose intravenous methylprednisolone constituted the basic treatment, but in most cases supplemental anti-inflammatory therapy was necessary. Outcome was acceptable without any mortality. Nevertheless, both lung function and diffusion capacity were in subnormal level though without any clinically functional impact.

Nontuberculous mycobacterial hypersensitivity pneumonitis related to a home shower: treatment and secondary prevention

A 57-year-old physician with increasing dyspnoea and hypoxaemia had a high-resolution CT scan of the chest, which disclosed diffuse pulmonary ground glass opacities, more pronounced in the upper lobes with minimal mediastinal lymphadenopathy. Transbronchial biopsy of the right middle and lower lobes was performed, demonstrating varying degrees of well circumscribed organising granulomatous pneumonitis thought to be most consistent with hypersensitivity to nontuberculous mycobacteria. Cultures of water obtained from the patient's home shower were positive for Mycobacterium avium complex. The patient began substituting baths for showers, experiencing some gradual improvement of his symptoms. Subsequently, he installed point-of-use 0.2 micron membrane filters on his shower, and resumed regular showering after installation with continued symptomatic improvement. CT scans at 3 and 18 months revealed improvement and resolution, respectively. Four years later, he continues to shower in filtered home shower water and remains clinically well.

The changing pattern of nontuberculous mycobacterial disease

Nontuberculous mycobacteria are human opportunistic pathogens whose source of infection is the environment. These include both slow-growing (eg, Mycobacterium kansasii and Mycobacterium avium) and rapid-growing (eg, Mycobacterium abscessus and Mycobacterium fortuitum) species. Transmission is through ingestion or inhalation of water, particulate matter or aerosols, or through trauma. The historic presentation of pulmonary disease in older individuals with predisposing lung conditions and in children has been changing. Pulmonary disease in elderly individuals who lack the classic predisposing lung conditions is increasing. Pulmonary disease and hypersensitivity pneumonitis have been linked with occupational or home exposures to nontuberculous mycobacteria. There has been a shift from Mycobacterium scrofulaceum to M avium in children with cervical lymphadenitis. Further, individuals who are immunosuppressed due to therapy or HIV-infection are at a greatly increased risk for nontuberculous mycobacterial infection. The changing pattern of nontuberculous mycobacterial disease is due in part to the ability of these pathogens to survive and proliferate in habitats that they share with humans, such as drinking water. The advent of an aging population and an increase in the proportion of immunosuppressed individuals suggest that the prevalence of nontuberculous mycobacterial disease will increase.

Nontuberculous mycobacterial lung diseases

Nontuberculous mycobacteria (NTM) are generally hardy, ubiquitous environmental bacteria that vary in geographic distribution and pulmonary pathogenicity. Relatively few of the more than 115 species of NTM have been associated with lung disease. Diagnosis of disease due to NTM relies on a combination of clinical, imaging, and microbiologic data. Because NTM may present as acid-fast bacilli in respiratory secretions of patients with clinical and radiologic features that mimic tuberculosis, laboratory discrimination of NTM from Mycobacterium tuberculosis is a priority. This discrimination is now often rapidly achievable using molecular techniques, although some tests have limited sensitivity. NTM species have different antibiotic response patterns, and success with medical treatment alone varies. Macrolides are an essential component of therapy for many species but must be combined with other drugs.

One hundred consecutive granulomas in a pulmonary pathology consultation practice

Lung biopsies showing granulomatous disease are commonly sent for expert pathology consultation. On the basis of features we and others have identified, an algorithmic approach to diagnosis of these cases was developed. We hypothesized that applying this approach would increase the likelihood of rendering a more specific diagnosis, or by rendering either a narrower or broader differential diagnosis, offer a more clinically useful diagnosis. One hundred consecutive lung biopsies from patients with granulomatous and giant cell reactions were retrieved from our consultation files. Cases were categorized into those in which a confident diagnosis was made at sign out, ones in which a specific diagnosis was strongly favored, and those in which a differential diagnosis was suggested. One year later follow-up information was obtained and consultation diagnoses were compared with clinical diagnoses to determine the reliability of the approach. A confident diagnosis was rendered in 27 cases, a specific diagnosis was strongly favored in 34, and in 39 a differential diagnosis was provided. Consultant diagnoses were more specific in 47 of 75 (63 %) cases. In 15 cases, the differential diagnosis was expanded. The most common unrecognized diagnosis was aspiration pneumonia and the most common diagnosis omitted from the differential diagnosis by the primary pathologist was hypersensitivity pneumonia. Follow-up in 49% of cases in which it was sought, confirmed the consultant's diagnosis or was inconclusive in 97% of cases. The use of a standardized algorithmic approach to the interpretation of granulomatous disease in lung biopsies yields more specific and clinically useful diagnoses for consideration.

Analysis of Actinobacteria from mould-colonized water damaged building material

Mould-colonized water damaged building materials are frequently co-colonized by actinomycetes. Here, we report the results of the analyses of Actinobacteria on different wall materials from water damaged buildings obtained by both cultivation-dependent and cultivation-independent methods. Actinobacteria were detected in all but one of the investigated materials by both methods. The detected concentrations of Actinobacteria ranged between 1.8 x 10(4) and 7.6 x 10(7) CFUg(-1) of investigated material. A total of 265 isolates from 17 materials could be assigned to 31 different genera of the class Actinobacteria on the basis of 16S rRNA gene sequence analyses. On the basis of the cultivation-independent approach, 16S rRNA gene inserts of 800 clones (50%) were assigned to 47 different genera. Representatives of the genera Streptomyces, Amycolatopsis, Nocardiopsis, Saccharopolyspora, Promicromonospora, and Pseudonocardia were found most frequently. The results derived from both methods indicated a high abundance and variety of Actinobacteria in water damaged buildings. Four bioaerosol samples were investigated by the cultivation-based approach in order to compare the communities of Actinobacteria in building material and associated air samples. A comparison of the detected genera of bioaerosol samples with those directly obtained from material samples resulted in a congruent finding of 9 of the overall 35 detected genera (25%), whereas four genera were only detected in bioaerosol samples.

Granulomatous lung disease: an approach to the differential diagnosis

CONTEXT

Granulomas are among the most commonly encountered abnormalities in pulmonary pathology and often pose a diagnostic challenge. Although most pathologists are aware of the need to exclude an infection in this setting, there is less familiarity with the specific histologic features that aid in the differential diagnosis.

OBJECTIVE

To review the differential diagnosis, suggest a practical diagnostic approach, and emphasize major diagnostically useful histologic features. This review is aimed at surgical pathologists who encounter granulomas in lung specimens.

DATA SOURCES

Pertinent recent and classic peer-reviewed literature retrieved from PubMed (US National Library of Medicine) and primary material from the institutions of both authors.

CONCLUSIONS

Most granulomas in the lung are caused by mycobacterial or fungal infection. The diagnosis requires familiarity with the tissue reaction as well as with the morphologic features of the organisms, including appropriate interpretation of special stains. The major noninfectious causes of granulomatous lung disease are sarcoidosis, Wegener granulomatosis, hypersensitivity pneumonitis, hot tub lung, aspiration pneumonia, and talc granulomatosis.