Pulmonary fungal infection: imaging findings in immunocompetent and immunocompromised patients

Pulmonary Infection

Pneumonia is a significant cause of morbidity and mortality in the community and hospital settings. Bacterial, viral, mycobacterial, and fungal pathogens are all potential causative agents of pulmonary infection. Chest radiographs and computed tomography are frequently utilized in the assessment of pneumonia. Learning the imaging patterns of different potential organisms allows the radiologist to formulate an appropriate differential diagnosis. An organism-based approach is used to discuss the imaging findings of different etiologies of pulmonary infection.

Pulmonary Histoplasmosis Mimicking Lung Cancer

Teaching point: Due to the mass-like appearance of pulmonary histoplasmosis in the lung, radiological misdiagnosis may occur. Fungal infections should be considered in the differential diagnosis, especially in immune-compromised patients.

A Case of Pulmonary Cryptococcosis Caused by Capsule-Deficient Cryptococcus neoformans

Cryptococcosis, a fungal infection primarily caused by Cryptococcus neoformans (CN), is a significant concern for immunocompromised individuals. This paper presents a case of a 51-year-old immunocompromised male who initially presented with symptoms suggestive of community-acquired pneumonia but was later diagnosed with pulmonary cryptococcosis caused by capsule-deficient CN. The patient's exposure to construction dust, coupled with his immunocompromised state due to immunosuppressive treatment for psoriatic arthritis, likely contributed to his susceptibility. The unique presentation of the disease, due to the absence of the characteristic thick capsule, presented a diagnostic challenge. A brief review is provided looking at the mechanism, pathogenesis, and implications of capsule deficiency in CN. The case provides an example of one of the many presentations of cryptococcosis, especially in immunocompromised individuals, and highlights the diagnostic complexities of capsule-deficient CN strains.

Imaging Findings in Aspergillosis: From Head to Toe

Aspergillosis is a mycotic infection induced by airborne fungi that are ubiquitous. Inhalation of Aspergillus conidia results in transmission through the respiratory tract. The clinical presentation is dependent on organism and host specifics, with immunodeficiency, allergies, and preexisting pulmonary disease constituting the most important risk factors. In recent decades, the incidence of fungal infections has increased dramatically, due in part to the increased number of transplants and the pervasive use of chemotherapy and immunosuppressive drugs. The spectrum of clinical manifestations can range from an asymptomatic or mild infection to a swiftly progressive, life-threatening illness. Additionally, invasive infections can migrate to extrapulmonary sites, causing infections in distant organs. Recognition and familiarity with the various radiological findings in the appropriate clinical context are essential for patient management and the prompt initiation of life-saving treatment. We discuss the radiological characteristics of chronic and invasive pulmonary aspergillosis, as well as some of the typically unexpected extrapulmonary manifestations of disseminated disease.

Chest Imaging in Systemic Endemic Mycoses

Endemic fungal infections are responsible for high rates of morbidity and mortality in certain regions of the world. The diagnosis and management remain a challenge, and the reason could be explained by the lack of disease awareness, variability of symptoms, and insidious and often overlooked clinical presentation. Imaging findings are nonspecific and frequently misinterpreted as other more common infectious or malignant diseases. Patient demographics and clinical and travel history are important clues that may lead to a proper diagnosis. The purpose of this paper is to review the presentation and differential diagnosis of endemic mycoses based on the most common chest imaging findings.

Application of metagenomic next-generation sequencing in the diagnosis of pulmonary invasive fungal disease

Background

Metagenomic next-generation sequencing (mNGS) is increasingly being used to detect pathogens directly from clinical specimens. However, the optimal application of mNGS and subsequent result interpretation can be challenging. In addition, studies reporting the use of mNGS for the diagnosis of invasive fungal infections (IFIs) are rare.

Objective

We critically evaluated the performance of mNGS in the diagnosis of pulmonary IFIs, by conducting a multicenter retrospective analysis. The methodological strengths of mNGS were recognized, and diagnostic cutoffs were determined.

Methods

A total of 310 patients with suspected pulmonary IFIs were included in this study. Conventional microbiological tests (CMTs) and mNGS were performed in parallel on the same set of samples. Receiver operating characteristic (ROC) curves were used to evaluate the performance of the logarithm of reads per kilobase per million mapped reads [lg(RPKM)], and read counts were used to predict true-positive pathogens.

Result

The majority of the selected patients (86.5%) were immunocompromised. Twenty species of fungi were detected by mNGS, which was more than was achieved with standard culture methods. Peripheral blood lymphocyte and monocyte counts, as well as serum albumin levels, were significantly negatively correlated with fungal infection. In contrast, C-reactive protein and procalcitonin levels showed a significant positive correlation with fungal infection. ROC curves showed that mNGS [and especially lg(RPKM)] was superior to CMTs in its diagnostic performance. The area under the ROC curve value obtained for lg(RPKM) in the bronchoalveolar lavage fluid of patients with suspected pulmonary IFIs, used to predict true-positive pathogens, was 0.967, and the cutoff value calculated from the Youden index was −5.44.

Conclusions

In this study, we have evaluated the performance of mNGS-specific indicators that can identify pathogens in patients with IFIs more accurately and rapidly than CMTs, which will have important clinical implications.

Imaging features of fungal pneumonia in haematopoietic stem cell transplant patients

Patients who have received haematopoietic stem cell transplantation (HSCT) have a high rate of pulmonary complications, and in this immunosuppressed population, fungal pneumonia is of great concern. Fungal pneumonia can have a similar appearance to non-infectious pulmonary processes in HSCT patients, and radiologists should be familiar with the subtle features that may help to differentiate these disease entities. The focus of this article is on the diagnosis of fungal pneumonia in HSCT patients with an emphasis on radiologists’ roles in establishing the diagnosis of fungal pneumonia and the guidance of clinical management.

Coccidioidomycosis in Brazil: Historical Challenges of a Neglected Disease

Coccidioidomycosis is a deep-seated fungal infection that occurs exclusively in semiarid areas in the Americas. In Brazil, coccidioidomycosis occurs exclusively in rural areas in the northeast region and affects counties that are hit by recurrent droughts, poverty and economic stagnation. Since 1978, approximately 136 cases of the disease have been reported in Brazil, according to scientific publications. However, a lack of governmental epidemiological data as well as a similarity to tuberculosis have led scientists and experts to assume that a greater number of cases occur in the country, which are not diagnosed and/or reported. In this review, general characteristics of coccidioidomycosis are presented, followed by a description of the main clinical and epidemiological data of cases in Brazil. The purpose of this article is to discuss the inclusion of coccidioidomycosis in the list of neglected tropical diseases. We believe that the adoption of coccidioidomycosis as a neglected tropical disease will enable the creation of an effective epidemiological surveillance system and the development of feasible public health solutions for its control in vulnerable populations.

Etiological profile and main imaging findings in patients with granulomatous diseases who underwent lung biopsy

Background

Granulomatous Lung Diseases (GLD) encompasses a wide range of infectious and non-infectious conditions characterized by chronic inflammatory response. However, different GLD may share similar imaging findings. In this context, the purpose of this study was to outline the etiological profile and their imaging features in patients with GLD who underwent lung biopsy.

Methods

Patients with granulomatous lesions in lung biopsies and previous chest CT performed from 2014 to 2017 at our institution had imaging data reviewed by three blinded radiologists. The imaging features were analyzed according to the Fleischner Society glossary. Categorical data were represented by absolute (n) and relative (%) frequency. The contingency matrices were analyzed by Pearson's Chi-square test. Interreader agreement was assessed by calculating the intraclass correlation coefficient, using kappa (κ) statistic.

Results

Thirty-eight of 75 (50.7%) patients were women with a mean age of 59 ± 39 years. Infection was the most common cause of GLD (47/75, 62.7%) and Histoplasma capsulatum (27/75, 36%) was the most prevalent etiology. Nodular pattern was the most common imaging feature in histoplasmosis cases (25/27, 92.6%), whereas it occurred in half of cases (24/48) of GLD of other causes (p < 0.05). Among patients with tuberculosis, the second etiology of GLD in our study population, the most common imaging pattern was centrilobular micronodules (3/7, 42.9%), significantly more frequent than in other causes of GLD (6/68, 8.8%). Interreader agreement in detecting imaging features was almost perfect (κ = 0.88-1.00), except the nodular pattern, which had substantial agreement (κ = 0.73).

Conclusions

In our study population, the main etiologies found in patients with granulomatous disease who underwent lung biopsy were fungal or mycobacterial disease, specially histoplasmosis and tuberculosis, and nodular pattern with focal distribution was the most common imaging finding which was detected with substantial interreader agreement.

Host Response to Coccidioides Infection: Fungal Immunity

Coccidioidomycosis is a fungal, respiratory disease caused by Coccidioides immitis and Coccidioides posadasii. This emerging infectious disease ranges from asymptomatic to pulmonary disease and disseminated infection. Most infections are cleared with little to no medical intervention whereas chronic disease often requires life-long medication with severe impairment in quality of life. It is unclear what differentiates hosts immunity resulting in disease resolution versus chronic infection. Current understanding in mycology-immunology suggests that chronic infection could be due to maladaptive immune responses. Immunosuppressed patients develop more severe disease and mouse studies show adaptive Th1 and Th17 responses are required for clearance. This is supported by heightened immunosuppressive regulatory responses and lowered anti-fungal T helper responses in chronic Coccidioides patients. Diagnosis and prognosis is difficult as symptoms are broad and overlapping with community acquired pneumonia, often resulting in misdiagnosis and delayed treatment. Furthermore, we lack clear biomarkers of disease severity which could aid prognosis for more effective healthcare. As the endemic region grows and population increases in endemic areas, the need to understand Coccidioides infection is becoming urgent. There is a growing effort to identify fungal virulence factors and host immune components that influence fungal immunity and relate these to patient disease outcome and treatment. This review compiles the known immune responses to Coccidioides spp. infection and various related fungal pathogens to provide speculation on Coccidioides immunity.

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.

Candida coinfection among patients with pulmonary tuberculosis in Asia and Africa; A systematic review and meta-analysis of cross-sectional studies

Diagnosis of fungal co-infections in patients suffering from pulmonary tuberculosis has critical importance. Therefore, we aimed to determine the prevalence of candida coinfection in patients with pulmonary tuberculosis. The present systematic review of cross-sectional studies was conducted based on the Preferred Reporting Items for Systematic reviews and Meta-analysis (PRISMA) Protocol. Studies published online in English from January 2001 to March 2019 were assessed. Literature search was done in Web of Science, MEDLINE/PubMed, and Scopus databases and search engines using keywords combinations of "pulmonary fungi", "pulmonary coinfection", OR "pulmonary mycosis", "pulmonary fungal infections/agents", OR "polymicrobial infection", OR "secondary infection", OR "mixed infections", "pulmonary candidiasis", "fungi coinfection", "fungal co-colonization", AND "pulmonary tuberculosis", OR "pulmonary TB", AND "Asia", AND "Africa". Data was analyzed using Comprehensive Meta-Analysis software (CMA). Heterogeneity between studies was evaluated by Cochran's Q and I² tests. The pooled prevalence of candida coinfection among patients with pulmonary tuberculosis was 25.7% (95% CI: 23.7-27.9). C. albicans was the most prevalent Candida spp. with a pooled prevalence of 65.8% (95% CI: 54.3-75.7). Risk factors of candida coinfection were smoking, diabetes, advanced age, and low body mass index. The present review showed a high rate of candida coinfection among patients suffering from pulmonary tuberculosis. So, appropriate measures are necessary to early diagnose and treat these infections.

Left destroyed lung caused by a pen cap in the left lower lobe bronchus "swallowed" 25 years ago

A delayed diagnosis of tracheobronchial foreign body aspiration (FBA) may result in severe respiratory complications such as pneumonia, bronchiectasis, and atelectasis. Here, we present a rare case of a left lung destruction caused by a pen cap that remained in the left lower lobe bronchus for 25 years and was previously misdiagnosed as cavitary tuberculosis. The foreign body was not detected in bronchoscopic examination prior to surgery due to severe stenosis of the left main bronchus. The foreign body was found incidentally while the patient was undergoing left pneumonectomy. To the best of our knowledge, this the second longest delay to diagnosis of FBA reported. This case also exemplifies the grave consequences of misdiagnosis of FBA.

Endemic pulmonary fungal diseases in immunocompetent patients: an emphasis on thoracic imaging

INTRODUCTION

Systemic endemic mycoses are prevalent in specific geographical areas of the world and are responsible for high rates of morbidity and mortality in these populations, and in immigrants and travelers returning from endemic regions. The most common fungal infections that can affect the lungs of immunocompetent patients include histoplasmosis, coccidioidomycosis, paracoccidioidomycosis, blastomycosis, sporotrichosis, aspergillosis, and cryptococcosis. Diagnosis and management of these diseases remain challenging, especially in non-endemic areas due to the lack of experience. Therefore, recognition of the various radiologic manifestations of pulmonary fungal infections associated with patients' clinical and epidemiologic history is imperative for narrowing the differential diagnosis. Areas covered: This review discusses the clinical and radiological findings of the main endemic fungal diseases affecting the lungs in immunocompetent patients. Specific topics discussed are their etiology, epidemiology, pathogenesis, clinical manifestations, methods of diagnosis, pathology and main imaging findings, especially in computed tomography. Expert commentary: Imaging plays an important role in the diagnosis and management of pulmonary fungal infection and may reveal useful signs. Although definitive diagnosis cannot be made based on imaging features alone, the use of a combination of epidemiologic, clinical and imaging findings may permit the formulation of an adequate differential diagnosis.

Imaging of Pulmonary Infections

Pulmonary infections have always been a cause of high morbidity and mortality, particularly in the pediatric and geriatric population and in immunocompromised hosts [1]. Pulmonary infections have various etiologies and have variegated patterns on radiographs and computed tomography (CT). Imaging plays an important role in the initial diagnosis and follow-up of various lung infections. Radiographs can be normal or non-specific during the initial evaluation, and CT findings may be more definitive. CT not only helps with the diagnosis but can also aid in management by guiding the diagnostic and therapeutic procedure. The pulmonary infections spread by direct or indirect contact with the infected host, droplet transmission, or an airborne spread. In rare cases, some infections can also be transmitted by vectors, namely, insect or animal hosts, and rarely by direct invasion from nearby infected organs. Pulmonary infections may have typical imaging patterns and distribution based on the mode of spread. There are a number of well-described imaging patterns of alveolar infections. The localization and morphological features on imaging may help in the diagnosis of infection and identification of mode of infection and, in certain cases, the microorganism responsible for the infection.

Tomographic assessment of thoracic fungal diseases: a pattern and signs approach

Pulmonary fungal infections, which can be opportunistic or endemic, lead to considerable morbidity and mortality. Such infections have multiple clinical presentations and imaging patterns, overlapping with those of various other diseases, complicating the diagnostic approach. Given the immensity of Brazil, knowledge of the epidemiological context of pulmonary fungal infections in the various regions of the country is paramount when considering their differential diagnoses. In addition, defining the patient immunological status will facilitate the identification of opportunistic infections, such as those occurring in patients with AIDS or febrile neutropenia. Histoplasmosis, coccidioidomycosis, and paracoccidioidomycosis usually affect immunocompetent patients, whereas aspergillosis, candidiasis, cryptococcosis, and pneumocystosis tend to affect those who are immunocompromised. Ground-glass opacities, nodules, consolidations, a miliary pattern, cavitary lesions, the halo sign/reversed halo sign, and bronchiectasis are typical imaging patterns in the lungs and will be described individually, as will less common lesions such as pleural effusion, mediastinal lesions, pleural effusion, and chest wall involvement. Interpreting such tomographic patterns/signs on computed tomography scans together with the patient immunological status and epidemiological context can facilitate the differential diagnosis by narrowing the options.

Case Definition of Chronic Pulmonary Aspergillosis in Resource-Constrained Settings

Chronic pulmonary aspergillosis (CPA) is a recognized complication of pulmonary tuberculosis (TB). In 2015, the World Health Organization reported 2.2 million new cases of nonbacteriologically confirmed pulmonary TB; some of these patients probably had undiagnosed CPA. In October 2016, the Global Action Fund for Fungal Infections convened an international expert panel to develop a case definition of CPA for resource-constrained settings. This panel defined CPA as illness for >3 months and all of the following: 1) weight loss, persistent cough, and/or hemoptysis; 2) chest images showing progressive cavitary infiltrates and/or a fungal ball and/or pericavitary fibrosis or infiltrates or pleural thickening; and 3) a positive Aspergillus IgG assay result or other evidence of Aspergillus infection. The proposed definition will facilitate advancements in research, practice, and policy in lower- and middle-income countries as well as in resource-constrained settings.

CT findings of fungal pneumonia with emphasis on aspergillosis

Fungal pneumonias are increasingly common in the population of immunosuppressed patients. The diagnosis of fungal pneumonias represents a challenge for clinicians, and the morbidity and mortality of these infections are high in immunocompromised patients. CT findings may be nonspecific; however, in the appropriate clinical setting, they may suggest and even help establish the specific diagnosis. This article provides an overview about the CT findings and possible differential diagnosis of the most common pulmonary fungal infections.

Diagnostic Imaging and Invasive Fungal Diseases in Children

Invasive fungal disease (IFD) is a life-threatening condition, especially in immunocompromised children. The role of diagnostic imaging in children at risk for an IFD is multifactorial, including initially detecting it, evaluating for dissemination of infection beyond the primary site of disease, monitoring the response to antifungal therapy, and assessing for potential relapse. The objective of this review was to synthesize the published literature relevant to the use of various imaging modalities for the diagnosis and management of IFD in children.

A case series of histoplasmosis patients with elevated serum soluble interleukin-2 receptor levels

Histoplasmosis is a common endemic mycosis that is usually asymptomatic but occasionally results in severe illness. Histoplasmosis and its causative agent, Histoplasma capsulatum, are found worldwide but rarely in Japan. In recent years, however, the number of histoplasmosis patients in Japan has increased. In addition, to our knowledge, there are no previous reports of increased serum soluble interleukin-2 receptor (sIL-2R) levels in patients with histoplasmosis. We report a case series of histoplasmosis in three Japanese temporary workers in Manzanillo, Mexico. All three patients developed a persistent high fever and general fatigue. Laboratory tests showed increased C-reactive protein levels and mild liver dysfunction. All patients also showed increased soluble interleukin-2 receptor (sIL-2R) levels. Chest computed tomography revealed multiple nodules in both lung fields. All patients were positive for serum anti-Histoplasma antibodies, and two patients were positive for Histoplasma on polymerase chain reaction tests. After treatment that included antifungals, their conditions gradually improved and laboratory data normalized. Although one patient developed respiratory failure, this patient recovered with antifungal therapy in combination with methylprednisolone. Serum sIL-2R levels in all patients gradually declined to normal levels, indicating their recovery from Histoplasma infection. From our experience with these patients, sIL-2R levels may be a useful biomarker for patients with histoplasmosis.

Respiratory infections in immunocompromised patients: Lung findings using chest computed tomography

Respiratory infections and subsequent complications are one of the leading causes of high mortality in immunocompromised patients. Although chest radiograph and computed tomography are the commonly used diagnostic tools for the early diagnosis of lung manifestations of infections, they lack the specificity for the wide range of chest infections which can occur in immunocompromised patients. Systematic analysis of the imaging findings in correlation with the clinical settings along with comparison with the old images can expedite early and accurate diagnosis for subsequent appropriate management. Computer tomography findings in immunocompromised patients with respiratory infections, with regards to various clinical settings, will be discussed here.

Differential Diagnosis of Cavitary Lung Lesions

Many different diseases present as cavitary pulmonary nodules. The spectrum of diseases ranges from acute to chronic infections, chronic systemic diseases, and malignancies. To decide on the most likely or correct diagnosis may be challenging. Knowledge of common and uncommon radiological findings in correlation with relevant clinical history and findings is necessary to make the right diagnosis and recommend the correct follow-up or step forward. The aim of this pictorial review is to present a brief overview of CT findings of common cavitary lung diseases seen in adult patients.

Acute exacerbation of interstitial pneumonia associated with rheumatoid arthritis during the course of treatment for Pneumocystis jirovecii pneumonia: a case report

Background

Pneumocystis jirovecii pneumonia (PCP) is potentially fatal infectious complication in patients with rheumatoid arthritis (RA) during immunosuppressive therapy. Hospital survival due to human immunodeficiency virus—unrelated PCP reaches to 60 %. The high mortality rate results from difficulties in establishing an early diagnosis, concurrent use of prophylactic drugs, possible bacterial coinfection. We herein report a case of PCP in RA patients who developed the architectural distortions of lung in spite of combined modality therapy.

Case presentation

A 73-year-old Japanese woman with RA was admitted with shortness of breath. Five weeks previously, she had been started on etanercept in addition to methotrexate (MTX). Chest computed tomography (CT) demonstrated diffuse ground glass opacities distributed throughout the bilateral middle to lower lung fields, and serum β-d-glucan was elevated. Bronchoalveolar lavage fluid revealed no P. jirovecii, but the organism was detected by polymerase chain reaction method. Trimethoprim/sulfamethoxazole was administered with methylprednisolone pulse therapy. However, the follow-up chest X-ray and chest CT demonstrated aggravation of the pneumonia with architectural distortions. Additional direct hemoperfusion with polymyxin B-immobilized fibers and intravenous cyclophosphamide therapy were insufficiently effective, and the patient died on day 25.

Conclusion

The architectural distortions of lung should be considered as a cause of death of PCP. For this reason, a high suspicion of this infectious complication must be kept in mind in order to establish an early diagnosis and treatment in patients with RA managed with MTX and biologics.

Multiple cystic lung disease

Multiple cystic lung disease represents a diverse group of uncommon disorders that can present a diagnostic challenge due to the increasing number of diseases associated with this presentation. High-resolution computed tomography of the chest helps to define the morphological aspects and distribution of lung cysts, as well as associated findings. The combination of appearance upon imaging and clinical features, together with extrapulmonary manifestations, when present, permits confident and accurate diagnosis of the majority of these diseases without recourse to open-lung biopsy. The main diseases in this group that are discussed in this review are lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis and folliculin gene-associated syndrome (Birt–Hogg–Dubé); other rare causes of cystic lung disease, including cystic metastasis of sarcoma, are also discussed. Disease progression is unpredictable, and understanding of the complications of cystic lung disease and their appearance during evolution of the disease are essential for management. Correlation of disease evolution and clinical context with chest imaging findings provides important clues for defining the underlying nature of cystic lung disease, and guides diagnostic evaluation and management.

Diagnosis of Invasive Fungal Diseases in Hematological Malignancies: A Critical Review of Evidence and Turkish Expert Opinion (TEO-2)

One of the most problematic issues in hematological malignancies is the diagnosis of invasive fungal diseases. Especially, the difficulty of mycological diagnosis and the necessity of immediate intervention in molds have led to the adoption of “surrogate markers” that do not verify but rather strongly suggest fungal infection. The markers commonly used are galactomannan (GM), beta-glucan, and imaging methods. Although there are numerous studies on these diagnostic approaches, none of these markers serve as a support for the clinician, as is the case in human immunodeficiency virus (HIV) or cytomegalovirus (CMV) infections. This paper has been prepared to explain the diagnostic tests. As molecular tests have not been standardized and are not used routinely in the clinics, they will not be mentioned here.

Aspergilloma and the surgeon

Aspergillus fungus is a ubiquitous saprophyte that is the causative organism for the development of an aspergilloma. The most common species causing an aspergilloma is the Apergillus fumigatus. An aspergilloma is a conglomeration of mucus, inflammatory cells and altered blood elements. Aspergillomas typically form in pre-existing lung pathology, most notably and commonly in old healed tuberculosis cavities. They are classified into simple and complex types that have clinical relevance. Symptoms are very variable and it is not uncommon to incidentally find a lung aspergilloma. In most case series, the most common presenting symptom is haemoptysis which varies from mild to catastrophic bleeds. Given the limited information about the natural history of the disease, there is unfortunately no recognised factor or variable which can predict how an aspergilloma will manifest itself, hence the manner of treatment is a still a topic of debate among treating physicians. The mainstay of treatment is surgical intervention and medical options although disappointing at the current stage, require further investigation in light of the newer available anti-fungal agents. The need for surgical intervention is however not as clear-cut as one would like, since many patients have multiple co-morbidities and other diffuse or focal lung pathology, making the decision process indeterminate in certain instances. In this review, we focus on the different surgical options available for the management of aspergilloma across variable clinical settings, and we propose an approach to its management.

Targeting UDP-galactopyranose mutases from eukaryotic human pathogens

UDP-Galactopyranose mutase (UGM) is a unique flavin-dependent enzyme that catalyzes the conversion of UDP-galactopyranose(UDP-Galp) to UDP-galactofuranose (UDP-Galf). The product of this reaction is the precursor to Galf, a major component of the cell wall and of cell surface glycoproteins and glycolipids in many eukaryotic and prokaryotic human pathogens. The function of UGM is important in the virulence of fungi, parasites, and bacteria. Its role in virulence and its absence in humans suggest that UGM is an ideal drug target. Significant structural and mechanistic information has been accumulated on the prokaryotic UGMs; however, in the past few years the research interest has shifted to UGMs from eukaryotic human pathogens such as fungi and protozoan parasites. It has become clear that UGMs from prokaryotic and eukaryotic organisms have different structural and mechanistic features. The amino acid sequence identity between these two classes of enzymes is low, resulting in differences in oligomeric states, substrate binding, active site flexibility, and interaction with redox partners. However, the unique role of the flavin cofactor in catalysis is conserved among this enzyme family. In this review, recent findings on eukaryotic UGMs are discussed and presented in comparison with prokaryotic UGMs.

Pulmonary complications in the non-HIV immunocompromised patient

The incidence of non-HIV immunocompromised patients is increasing. This is primarily due to improved immunosuppressive regimes for autoimmune diseases and also increases in stem cell transplantation. Pulmonary complications are a major cause of morbidity and mortality in these patients. Imaging is frequently used to assess these complications and to streamline therapies, as microbiological and/or pathological diagnosis can often be difficult, invasive, or protracted. This review provides the reader with a structured approach to interpret the imaging findings and differentiate between different infective and non-infective complications in these patients.

Crystal structures and small-angle x-ray scattering analysis of UDP-galactopyranose mutase from the pathogenic fungus Aspergillus fumigatus

UDP-galactopyranose mutase (UGM) is a flavoenzyme that catalyzes the conversion of UDP-galactopyranose to UDP-galactofuranose, which is a central reaction in galactofuranose biosynthesis. Galactofuranose has never been found in humans but is an essential building block of the cell wall and extracellular matrix of many bacteria, fungi, and protozoa. The importance of UGM for the viability of many pathogens and its absence in humans make UGM a potential drug target. Here we report the first crystal structures and small-angle x-ray scattering data for UGM from the fungus Aspergillus fumigatus, the causative agent of aspergillosis. The structures reveal that Aspergillus UGM has several extra secondary and tertiary structural elements that are not found in bacterial UGMs yet are important for substrate recognition and oligomerization. Small-angle x-ray scattering data show that Aspergillus UGM forms a tetramer in solution, which is unprecedented for UGMs. The binding of UDP or the substrate induces profound conformational changes in the enzyme. Two loops on opposite sides of the active site move toward each other by over 10 Å to cover the substrate and create a closed active site. The degree of substrate-induced conformational change exceeds that of bacterial UGMs and is a direct consequence of the unique quaternary structure of Aspergillus UGM. Galactopyranose binds at the re face of the FAD isoalloxazine with the anomeric carbon atom poised for nucleophilic attack by the FAD N5 atom. The structural data provide new insight into substrate recognition and the catalytic mechanism and thus will aid inhibitor design.

Surgical treatment of pulmonary aspergilloma

The objective of this study was to analyze the outcome of surgical treatment of pulmonary aspergilloma. To that end, we evaluated 14 adult patients so treated between 1981 and 2009 at the Botucatu School of Medicine University Hospital, in the city of Botucatu, Brazil. Data were collected from the medical records of the patients. Ten patients (71%) presented with simple pulmonary aspergilloma, and 4 (29%) presented with complex pulmonary aspergilloma. Hemoptysis was the most common symptom, and tuberculosis was the most prevalent preexisting lung disease. Two patients (14%) underwent surgery on more than one occasion. There were no intraoperative deaths. Half of the patients developed postoperative complications, prolonged air leak and empyema being the most common.

HRCT-features of Pneumocystis jiroveci pneumonia and their evolution before and after treatment in non-HIV immunocompromised patients

OBJECTIVE

This study retrospectively analyzes the characteristics and kinetics of pulmonary changes in Pneumocystis jiroveci pneumonia (PJP) before and after treatment as depicted by thin-section-CT in HIV-negative patients.

MATERIALS AND METHODS

Serial CT scans of 84 consecutive HIV-negative PJP patients were reviewed retrospectively encompassing a median follow-up of 76 (range, 37-506) days. Along with underlying disease and time span between the onset of symptoms and specific antimicrobial therapy, early and late pulmonary CT-findings were evaluated.

RESULTS

Imaging findings at initial diagnosis differed from those in the posttherapeutic setting. In the acute (initial) PJP-phase, most frequent finding was symmetric, apically distributed ground glass opacities (GGO) with peripheral sparing 43% (n = 36). These initial changes resolved up to 1st follow-up-examination in 57% (n = 48), and finally in all except for two patients after a median period of 13 (mean 26, range 1-58) days following application of specific therapy. In 42% (n = 35) architectural distortions occurred, but they resolved after a median period of 27 (mean 60, range 11-302) days. Only in 9 patients, complete resolution could not be documented. Significant correlations of the underlying disease or the time span between the onset of symptoms and specific antibiotic therapy and morphologic kinetic could not be found.

CONCLUSION

Thin-section CT-findings of PJP usually resolve soon after onset of specific therapy. Postinfectious fibrosis rarely occurs following PJP in HIV-negative patients.

Pleuropulmonary Changes Induced by Drugs in Patients with Hematologic Diseases

Patients with hematologic diseases who are being treated with therapy drugs, or receive radiation therapy or blood transfusions may develop a host of potentially fatal infectious and noninfectious pulmonary complications [1]. The increased complexity of multimodality and high-dose treatment regimens with the intended benefit of augmented antineoplastic efficacy and prolonged disease-free survival, the use of a panel of novel drugs to treat malignant and nonmalignant hematologic conditions (e.g., azacytidine, bortezomib, cladribine, dasatinib, fludarabine, imatinib, lenalidomide, rituximab, and thalidomide), total body irradiation (TBI) and hematopietic stem cell transplantation (HSCT) have increased the incidence of severe sometimes life-threatening pulmonary complications.

Hemoptysis and thoracic fungal infections

Hemoptysis and thoracic fungal infections are infrequent but challenging problems, especially when encountered in the emergency setting. The evaluation and management of massive and nonmassive hemoptysis is described with special attention to radiologic, bronchcoscopic, and surgical interventions. The important principles of airway control, stabilization, and definitive management are emphasized. Endemic and opportunistic fungal infections are more common than they seem. The role of the surgeon is to assist in diagnosis, evaluate and treat pulmonary nodules, and consider resectional therapy for mycetoma and invasive fungal infections in selected candidates.

Characterization of recombinant UDP-galactopyranose mutase from Aspergillus fumigatus

UDP-galactopyranose mutase (UGM) is a flavin-containing enzyme that catalyzes the conversion of UDP-galactopyranose to UDP-galactofuranose, the precursor of galactofuranose, which is an important cell wall component in Aspergillus fumigatus and other pathogenic microbes. A. fumigatus UGM (AfUGM) was expressed in Escherichia coli and purified to homogeneity. The enzyme was shown to function as a homotetramer by size-exclusion chromatography and to contain approximately 50% of the flavin in the active reduced form. A k(cat) value of 72 +/- 4 s(-1) and a K(M) value of 110 +/- 15 microM were determined with UDP-galactofuranose as substrate. In the oxidized state, AfUGM does not bind UDP-galactopyranose, while UDP and UDP-glucose bind with K(d) values of 33 +/- 9 microM and 90 +/- 30 microM, respectively. Functional and structural differences between the bacterial and eukaryotic UGMs are discussed.

Chronic cavitary pulmonary histoplasmosis

Histoplasmosis is a systemic mycosis caused by the thermally dimorphic fungus Histoplasma capsulatum, which can be isolated from soil contaminated with droppings from birds or bats. Chronic cavitary pulmonary histoplasmosis is one of the rarest clinical presentations of this disease. The differential diagnosis with tuberculosis should be made in patients presenting with cavitated lesions in upper lung segments. We report the case of a female patient with chronic cavitary pulmonary histoplasmosis who had presented with progressive dyspnea and worsening of the radiological pattern over a four-year period.

Microbial aetiologic agents associated with pneumonia in immunocompromised hosts

Pulmonary infections are a major cause of morbidity and mortality in the immunosuppressed patients. The aim of this study was to determine the etiologic agents and predisposing factors associated with pneumonia infections in immunocompromised patients. Cross-sectional survey of 100 immunocompromised patients due to HIV and Mycobacterium tuberculosis infections were enlisted for the study. The patients completed a structured questionnaire to abstract information on demographic features and risk factors. Sputum samples were collected from the patients with clinical suspicion of having pneumonia and the sputa examined by cultural methods. The tuberculosis patients had the highest number of isolates, 119 (70%) while those with co-infections of HIV/AIDS and tuberculosis had 41(24.1%) and those with only HIV infection were 10 (5.9%). The distribution of isolates were as follows, Staphylococcus aureus 63 (37.9%), Streptococcus pyogenes 44 (25.9%), Streptococcus pneumoniae 27 (15.9%), Candida albicans 24 (14.1%), Klebsiella pneumoniae 7 (4.1%), Proteus mirabilis 4 (2.4%) and Escherichia coli 1 (0.5%). Those with previous history of alcoholism and tobacco smoking had relatively high isolates. This study demonstrated that secondary infections are prevalent in the immunocompromised patients due to HIV/AIDS and TB or co-infection with TB/HIV-AIDS. This may lead to drug resistance, DOTS or HAART programme, thereby leading to high mortality and morbidity.

Coccidioidomycosis and tuberculosis coinfection at a tuberculosis hospital: clinical features and literature review

Tuberculosis (TB) and coccidioidomycosis can have similar clinical and radiologic presentations but require different treatments. Coinfection with TB and Coccidioides immitis is uncommonly reported and may be underdiagnosed in endemic areas.We performed a retrospective review of the medical records of all patients admitted to a TB referral hospital between 1995 and 2007, and selected all cases of TB and coccidioidomycosis coinfection in patients aged 18 years or older. All admitted patients had a diagnosis of TB and had sputum cultures for both pathogens. We reviewed clinical, laboratory, and radiologic features of the cases, and noted antimicrobial treatments received and outcomes.We identified 9 patients, of whom 7 (78%) were Hispanic. Most patients were male (8/9, 89%), and all were diagnosed with coccidioidomycosis after TB. Three (33%) patients had drug-resistant TB. Six patients had culture-positive TB at the time of the double diagnosis, and 2 patients developed active coccidioidomycosis during their hospital stay. Only 1 had human immunodeficiency virus/acquired immunodeficiency syndrome (HIV-AIDS) (CD4 count, 20 cells/mm). All but 2 patients were treated with antifungal agents. Two patients died, 1 of whom had AIDS. Radiologic studies were unable to distinguish between TB and coccidioidomycosis, except for a patient who developed a new air-fluid level in a previously stable cavity.TB and coccidioidomycosis coinfection should be suspected in coccidioidomycosis-endemic regions among patients with TB who fail to improve clinically or radiologically despite adequate, culture-directed therapy.

Blastomycosis in the mountainous region of northeast Tennessee

BACKGROUND

In the United States, cases of human blastomycosis are largely described in defined geographic areas, with Mississippi reporting the highest prevalence of disease in the southeast region. The infection is uncommonly recognized in mountainous areas, and our previous report of blastomycosis in the southern Appalachian mountains of northeast Tennessee appeared to be an exception to the usual disease distribution.

METHODS

Our current retrospective study was undertaken to determine whether blastomycosis has persisted as an endemic fungal infection in our northeast Tennessee geographic area and whether epidemiologic features have changed over a 25-year time period.

RESULTS

Results show that clinical aspects of the disease have remained fairly constant with few exceptions; mass-type pulmonary lesions have become more common, and itraconazole has emerged as the therapy of choice. Most notably, however, are the observations that blastomycosis persists as a major endemic fungal infection in our mountain region, more than half of all cases occurring during the period from 1996 to 2005 were found in a core area centered on two counties, Washington and Unicoi; three of five counties surrounding the core counties experienced rate increases compared to our previous study.

CONCLUSIONS

These findings suggest a further expansion of this endemic fungal disease beyond the core region.

Computed tomography for the diagnosis of infectious diseases of the chest

BACKGROUND

Pulmonary infection is a common reason for imaging of the lung in immunocompetent and immunosuppressed patients. Findings on chest radiography are nonspecific and encompass poor sensitivity. The role of computed tomography (CT) has been evolving in the diagnosis of lung infections.

OBJECTIVE

This paper reviews recent developments in the efficacy and utility of CT in the diagnosis of suspected pulmonary infections in a variety of patient populations.

METHODS

Recent published literature was reviewed to prepare this treatise on the role of CT.

CONCLUSION

Knowledge and skills at pattern recognition are crucial for the CT interpretation in lung infections. Computed tomography scan is increasingly used to increase the sensitivity of the radiologic diagnosis of thoracic infections. The greatest value of CT is when the radiograph is normal, findings are equivocal, and to differentiate infection from non-infectious disorders.