Update on invasive aspergillosis: clinical and diagnostic aspects

A novel procedure for the quantification of antifungal activity against filamentous fungi, mycelial invasion distance (MID) method

A novel method for the quantification of antifungal activity of fungicides and painted surfaces, mycelial invasion distance (MID) method, was developed and applied to the quantification of activities of parabens and an antifungal paint. In this method, the MID of aerial mycelia on a test paper or a panel placed on a nutrient agar plate was measured with a stereoscopic microscope and a micro-ruler. The antifungal activities of the parabens and painted surfaces were expressed as the MID. The higher the hydrophobicity of parabens, the longer the MID, that is the lower the antifungal activity, were observed. Conversely, relatively polar parabens, such as methyl and ethyl parabens, exhibited stronger antifungal activity, that is shorter MID. The most hydrophobic paraben, benzyl paraben, showed the weakest antifungal activity. Furthermore, it was confirmed that the MID method was effective for the evaluation of the painted surfaces.

Case Report and Clinical Reasoning: Fulminant Liver Failure and Invasive Aspergillosis Following Ocrelizumab Treatment in a 21 Year-Old Woman

We present the case of a 21 year-old woman with newly diagnosed relapsing-remitting multiple sclerosis who is given a single dose of ocrelizumab and placed on moderate-dose steroids with subsequent development of hepatic failure who goes on to develop highly fulminant systemic and central nervous system (CNS) aspergillosis. Ocrelizumab has no documented association with aspergillus infection, and moderate-dose steroids less often lead to such fulminant disease, but liver failure is associated with often-fatal aspergillus infection. We emphasize that liver failure is an underrecognized immune dysregulated state that predisposes to bacterial and fungal infections and suggest changes in diagnostic reasoning that could be considered in patients with multiple modalities of immunosuppression.

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

Spinal epidural abscess caused by Aspergillus spp masquerading as spinal tuberculosis in a person with HIV

Spinal epidural abscess caused by Aspergillus spp is a debilitating form of invasive aspergillosis that can easily be misdiagnosed as spinal tuberculosis due to shared risk factors and clinical features. In this Grand Round, we describe a case of thoracic aspergillus spinal epidural abscess in a patient with underlying HIV infection. The initial diagnostic consideration was that of spinal tuberculosis. Consequently, despite positive microbiological cultures of Aspergillus fumigatus, antifungal therapy was delayed until histopathological evaluation of the affected tissue confirmed the presence of fungal hyphae. The patient showed an initial favourable response after surgical removal of the infected focus, but unfortunately never returned to premorbid functioning. This case highlights the importance of early diagnosis, urgent surgery, and prompt antifungal therapy for the management of aspergillus spinal epidural abscesses. Associated morbidity and mortality can be substantially increased if physicians fail to recognise this condition and do not institute appropriate and timely surgical and medical treatment.

Advances in the In Vivo Molecular Imaging of Invasive Aspergillosis

Invasive pulmonary aspergillosis (IPA) is a life-threatening infection of immunocompromised patients with Aspergillus fumigatus, a ubiquitous environmental mould. While there are numerous functioning antifungal therapies, their high cost, substantial side effects and fear of overt resistance development preclude permanent prophylactic medication of risk-patients. Hence, a fast and definitive diagnosis of IPA is desirable, to quickly identify those patients that really require aggressive antimycotic treatment and to follow the course of the therapeutic intervention. However, despite decades of research into this issue, such a diagnostic procedure is still not available. Here, we discuss the array of currently available methods for IPA detection and their limits. We then show that molecular imaging using positron emission tomography (PET) combined with morphological computed tomography or magnetic imaging is highly promising to become a future non-invasive approach for IPA diagnosis and therapy monitoring, albeit still requiring thorough validation and relying on further acceptance and dissemination of the approach. Thereby, our approach using the A. fumigatus-specific humanized monoclonal antibody hJF5 labelled with ⁶⁴Cu as PET-tracer has proven highly effective in pre-clinical models and hence bears high potential for human application.

Aspergilloma clinically mimicking Achilles tendon xanthoma in a non-immunocompromised patient: A case report

A 48-year-old woman visited our outpatient clinic complaining of discomfort while wearing shoes due to a large mass around her Achilles tendon. The mass was firm, non-tender, non-reducible, and moved with the Achilles tendon, similar to Achilles tendon xanthoma. However, magnetic resonance imaging revealed multiple heterogeneous, nodular lesions with low T1 and T2 signal intensity, and histological examination of the biopsy specimen revealed the mass to contain hyphae of Aspergillus, indicating aspergilloma. The purpose of this case report is to emphasize that a tumor around the Achilles tendon can be something other than xanthoma even when the clinical features are typical of xanthoma. LEVEL OF CLINICAL EVIDENCE: 4.

In vitro study on aspects of molecular mechanisms underlying invasive aspergillosis caused by gliotoxin and fumagillin, alone and in combination

Gliotoxin (GT) and fumagillin (FUM) are mycotoxins most abundantly produced by Aspergillus fumigatus during the early stages of infection to cause invasive aspergillosis (IA). Therefore, we hypothesized that GT and FUM could be the possible source of virulence factors, which we put to test adopting in vitro monoculture and the novel integrated multiple organ co-culture (IdMOC) of A549 and L132 cell. We found that (i) GT is more cytotoxic to lung epithelial cells than FUM, and (ii) GT and FUM act synergistically to inflict pathology to the lung epithelial cell. Reactive oxygen species (ROS) is the master regulator of the cytotoxicity of GT, FUM and GT + FUM. ROS may be produced as a sequel to mitochondrial damage and, thus, mitochondria are both the source of ROS and the target to ROS. GT-, FUM- and GT + FUM-induced DNA damage is mediated either by ROS-dependent mechanism or directly by the fungal toxins. In addition, GT, FUM and GT + FUM may induce protein accumulation. Further, it is speculated that GT and FUM inflict epithelial damage by neutrophil-mediated inflammation. With respect to multiple organ cytotoxicity, GT was found to be cytotoxic at IC50 concentration in the following order: renal epithelial cells < type II epithelial cells < hepatocytes < normal lung epithelial cells. Taken together, GT and FUM alone and in combination contribute to exacerbate the damage of lung epithelial cells and, thus, are involved in the progression of IA.

Identification of Aspergillus Conidia in Bronchoalveolar Lavage Using Offline Combination of Capillary Electrophoresis in Supercritical Water-Treated Fused Silica Capillary and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Diagnosis of fungal infection in lung parenchyma is relatively difficult. Bronchoscopy with bronchoalveolar lavage is very useful in its diagnosing. Therefore, a method for rapid online concentration and analysis of Aspergillus conidia in bronchoalveolar lavage fluid using the combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) with subsequent off-line identification of the separated conidia by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is described in this study. In the proposed procedure, conidia were first dynamically adhered onto the roughened part of the inner surface of a fused silica capillary prepared by etching with supercritical water. Then the adhered conidia were desorbed, concentrated, and separated using a combination of tITP and MEKC. Finally, the fractions containing the separated conidia were collected from the capillary and analyzed by MALDI-TOF MS. The adhesion efficiency under the optimized experimental conditions was about 80%. This rapid diagnosis will contribute to timely initiation of therapy and increase the patient's chances of survival.

Case report: Disseminated aspergillosis complicating influenza

Aspergillus can cause a wide variety of diseases ranging from hypersensitivity diseases to invasive infection. Invasive disease most commonly occurs in severely immunocompromised patients such as chemotherapy-induced neutropenia and transplantation. It is a less well-recognized complication in critically ill patients without traditional risk factors. We describe a case of invasive aspergillosis complicating influenza and diabetic ketoacidosis that disseminated to the central nervous system and led to demise despite high-intensity antifungal therapy.

Retrospective evaluation of in vitro effect of gentamicin B1 against Fusarium species

The in vitro susceptibility of gentamicin fractions against Fusarium growth was the subject of this retrospective study. Fusariosis was earlier an exceptionally rare human disease and an unrealistic idea to treat soil saprophytes and plant pathogens with expensive antibiotics such as gentamicins or their minor components. Disseminated fusariosis is now the second most frequent lethal fungal infection after aspergillosis especially in neutropenic patients with hematologic malignancy. Results of this study obtained between May and November 1973 were interesting but not practicable and remained unpublished. Seven Fusarium and 28 other fungal strains were tested for their susceptibility to gentamicin B1. The anti-Fusarium activity of gentamicin B1 was between 0.2 and 3.1 μg/ml minimum inhibitory concentration (MIC) values. The MIC values of clotrimazol and amphotericin B against Fusarium species were significantly higher, 3.1-12.5 μg/ml and 3.1-50 μg/ml, respectively. Gentamicin B1 and its structurally related congeners including hygromycin B, paromomycin, tobramycin (nebramycin factor 5'), nebramycin (nebramycin factor 4), and sisomicin exerted strong in vitro inhibition against Fusarium species between 0.2 and 12.5 μg/ml concentrations. The antibacterial MIC concentration of gentamicin B1 tested on 20 bacterial strains ranged between 0.1 and 50 μg/ml. Gentamicin B1, a minor fraction of the gentamicin complex, inhibited effectively the growth of Gram-positive (Staphylococcus, Streptococcus, Bacillus subtilis) bacteria and Gram-negative (Escherichia coli, Salmonella, Proteus, Pseudomonas) pathogens. Gentamicins and related aminoglycoside antibiotics are used in medical practice. It is proposed that due to the increasing incidence of fusariosis and drug resistance, gentamicin components, particularly minor fraction B1 and related aminoglycoside antibiotics, could be tested for their in vivo activity against fusariosis and aspergillosis either alone or in combination with other antifungal agents.

Endomyocardial and pericardial aspergillosis in critically ill patients

Invasive aspergillosis(IA) is a potentially lethal complication of Aspergillus infection affecting mainly immunocompromised hosts; however, during the last two decades its incidence was increasingly observed in critically ill immunocompetent patients. The objective of this study is to describe the clinical characteristics of histologically proven endomyocardial and pericardial invasion, in the context of IA, in critically ill patients. Eight critically ill patients with histopathological confirmation of endomyocardial/pericardial aspergillosis were evaluated. Risk factors, clinical and laboratory characteristics, treatment, histopathological characteristics and mortality were recorded. Signs and symptoms of cardiac dysfunction were not observed in any of the patients. Therapy was administered to six of them shortly after the first positive culture. The observed histopathological lesions included haemorrhagic lesions, small vessels with central thrombosis and surrounding consolidated tissue with necrosis. Voriconazole, caspofungin, lipid amphotericin B and itraconazole were the used antifungals. The mortality rate was high (87.5%). Endomyocardial and pericardial aspergillosis are devastating complications of invasive aspergillosis. Clinical suspicion is low making the diagnosis difficult, therefore histopathological examination of tissues are required. The mortality is high.

Development of Aspergillosis in a cohort of non-neutropenic, non-transplant patients colonised by Aspergillus spp

BACKGROUND

A previous study explored factors discriminating colonization and true infection among non-transplant, non-neutropenic patients with repeated Aspergillus spp. isolation from lower respiratory samples. The present study explored the evolution of patients with Aspergillus colonization in that study to determine the percentage of cases progressing to aspergillosis and time to development.

METHODS

Clinical records were retrospectively reviewed (for each patient from his end date in the past study) and data from all respiratory processes suffered by patients up to April 2015 were recorded. Comparisons of variables were performed between colonized patients that developed aspergillosis and those that did not. A Kaplan-Meier curve was used to describe time to development of aspergillosis in chronic obstructive pulmonary disease (COPD) patients for II-IV stages of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification.

RESULTS

Sixty seven colonized patients were followed, 12 of them (17.9%) developed aspergillosis. Diagnoses included six tracheobronchitis (4 invasive, 2 simple tracheobronchitis), four pulmonary disease (2 invasive pulmonary aspergillosis, 2 chronic pulmonary aspergillosis), one allergic bronchopulmonary aspergillosis and one pulmonary aspergilloma. Up to 47 (70.4%) of the study patients presented COPD. Among patients developing aspergillosis COPD was more frequent (100%) than among those that did not develop aspergillosis (35 out of 55; 63.6%) (p = 0.012), as well as GOLD IV patients were more frequent among COPD patients developing aspergillosis than among COPD patients that did not (50.0 vs. 26.1%, p = 0.046). Mean time to development of aspergillosis was 18.4 months (median: 8.5) with a wide range (1-58). Overtime, the percentage of patients developing aspergillosis was significantly higher among GOLD IV patients than among GOLD II-III patients (p = 0.032).

CONCLUSIONS

The high percentage of cases progressing to aspergillosis among colonized patients, especially among those with COPD (25.5%), stresses the importance of colonization as risk factor, and creates awareness of the possible change from colonization to invasive disease in GOLD IV patients.

Clinical Effectiveness, Safety Profile, and Pharmacokinetics of Daptomycin in Pediatric Patients: A Systematic Review

Infections by Gram-positive pathogens pose a public health risk, especially due to increasing antibiotic resistance. Daptomycin has efficacy against most clinically important Gram-positive bacteria. Although experience regarding use of daptomycin in adults is increasing, studies on pediatric populations are limited. We aimed to evaluate the efficacy, safety, and pharmacokinetics of daptomycin in pediatric settings. We searched MEDLINE and Clinicaltrials.gov (through April 2016) and included 29 original studies in the final analysis. Available evidence suggests that daptomycin in pediatric patients has a favorable safety and tolerability profile and is an efficacious alternative for treatment of Gram-positive bacteremia, endocarditis, and infections of the skin, soft tissues, joints, and bones, especially when resistant strains are involved. However, future studies need to address several issues to determine the optimal dose and various pharmacokinetic parameters in different pediatric age groups.

Infections after orthotopic liver transplantation

Opportunistic infections are a leading cause of morbidity and mortality after orthotopic liver transplantation. Systemic immunosuppression renders the liver recipient susceptible to de novo infection with bacteria, viruses and fungi post-transplantation as well to reactivation of pre-existing, latent disease. Pathogens are also transmissible via the donor organ. The time from transplantation and degree of immunosuppression may guide the differential diagnosis of potential infectious agents. However, typical systemic signs and symptoms of infection are often absent or blunted after transplant and a high index of suspicion is needed. Invasive procedures are often required to procure tissue for culture and guide antimicrobial therapy. Antimicrobial prophylaxis reduces the incidence of opportunistic infections and is routinely employed in the care of patients after liver transplant. In this review, we survey common bacterial, fungal, and viral infections after orthotopic liver transplantation and highlight recent developments in their diagnosis and management.

[Invasive pulmonary aspergillosis in patients with chronic obstructive pulmonary disease]

Invasive pulmonary aspergillosis (IPA) is a common infection in immunocompromised patients with hematological malignancies or allogenic stem cell transplantation, and is less frequent in the context of chronic obstructive pulmonary disease (COPD). Mucociliary activity impairment, immunosuppression due to the inhibition of alveolar macrophages and neutrophils by steroids, and receiving broad-spectrum antibiotics, play a role in the development of IPA in COPD patients. Colonized patients or those with IPA are older, with severe CODP stage (GOLD≥III), and have a higher number of comorbidities. The mortality rate is high due to the fact that having a definitive diagnosis of IPA in COPD patients is often difficult. The main clinical and radiological signs of IPA in these types of patients are non-specific, and tissue samples for definitive diagnosis are often difficult to obtain. The poor prognosis of IPA in COPD patients could perhaps be improved by faster diagnosis and prompt initiation of antifungal treatment. Some tools, such as scales and algorithms based on risk factors of IPA, may be useful for its early diagnosis in these patients.

Systemic mycoses in immunodepressed patients (AIDS)

Infectious and noninfectious skin diseases are observed in about 90% of HIV patients, and their incidence increases and is more severe as the immune system weakens. Cutaneous manifestations are considered good clinical predictors for the immunological condition of the patient with AIDS and the introduction of highly effective antiretroviral therapy totally changed the prognosis of the mycoses, among other diseases associated with AIDS, permitting longer survival and acceptable level of quality of life for these patients. This contribution describes the systemic mycoses that are more frequent in the seropositive population, that is, patients with HIV/AIDS, which are cryptococcosis, histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, sporotrichosis, penicilliosis, and aspergillosis. Their causative agents, mode of transmission, clinics, laboratorial diagnosis and therapy, in the aspects related to immunodepressed patients, are reviewed.

Invasive aspergillosis caused by cryptic Aspergillus species: a report of two consecutive episodes in a patient with leukaemia

We report a case of two consecutive episodes of invasive aspergillosis caused by cryptic Aspergillus species in a patient with leukaemia. A first episode of pulmonary infection was caused by Aspergillus calidoustus and Aspergillus novofumigatus, and the second episode by A. novofumigatus and Aspergillus viridinutans. Fungal isolates were identified to species level using traditional and sequencing-based molecular methods.

Preclinical evaluation of two 68Ga-siderophores as potential radiopharmaceuticals for Aspergillus fumigatus infection imaging

Purpose

Invasive pulmonary aspergillosis is mainly caused by Aspergillus fumigatus, and is one of the major causes of morbidity and mortality in immunocompromised patients. The mortality associated with invasive pulmonary aspergillosis remains high, mainly due to the difficulties and limitations in diagnosis. We have shown that siderophores can be labelled with ⁶⁸Ga and can be used for PET imaging of A. fumigatus infection in rats. Here we report on the further evaluation of the most promising ⁶⁸Ga-siderophore candidates, triacetylfusarinine (TAFC) and ferrioxamine E (FOXE).

Methods

Siderophores were labelled with ⁶⁸Ga using acetate buffer. Log P, protein binding and stability values were determined. Uptake by A. fumigatus was studied in vitro in cultures with high and low iron loads. In vivo biodistribution was determined in normal mice and an infection model was established using neutropenic rats inoculated with A. fumigatus. Static and dynamic μPET imaging was performed and correlated with CT images, and lung infection was evaluated ex vivo.

Results

⁶⁸Ga-siderophores were labelled with high radiochemical purity and specific activity. ⁶⁸Ga-TAFC and ⁶⁸Ga-FOXE showed high uptake by A. fumigatus in iron-deficient cultures. In normal mice, ⁶⁸Ga-TAFC and ⁶⁸Ga-FOXE showed rapid renal excretion with high metabolic stability. In the rat infection model focal lung uptake was detected by μPET with both compounds and increased with severity of the infection, correlating with abnormal CT images.

Conclusion

⁶⁸Ga-TAFC and ⁶⁸Ga-FOXE displayed excellent in vitro stability and high uptake by A. fumigatus. Both compounds showed excellent pharmacokinetics, highly selective accumulation in infected lung tissue and good correlation with severity of disease in a rat infection model, which makes them promising agents for A. fumigatus infection imaging.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-012-2110-3) contains supplementary material, which is available to authorized users.

Invasive fungal infections in liver transplantation

Invasive fungal infections (IFIs) in immunocompromised patients, particularly liver transplant recipients, are the subject of increasing clinical attention. Although the overall incidence of fungal infections in liver transplant recipients has declined due to the early treatment of high-risk patients, the overall mortality rate remains high, particularly for invasive candidiasis and aspergillosis. IFIs after liver transplantation are strongly associated with negative outcomes, increasing the cost to recipients. Numerous studies have attempted to determine the independent risk factors related to IFIs and to reduce the morbidity and mortality with empirical antifungal prophylaxis after liver transplantation. Unfortunately, fungal infections are often diagnosed too late; symptoms can be mild and non-specific even with dissemination. Currently, no consensus exists on which patients should receive antifungal prophylaxis, when prophylaxis should be given, which antifungal agents should be used, and what duration is effective. This review highlights the types of IFI, risk factors, diagnosis, antifungal prophylaxis, and treatment after liver transplantation. With the early identification of patients at high risk for IFIs and the development of new molecular diagnostic techniques for early detection, the role of antifungal compounds in fungal infection prophylaxis needs to be established to improve the survival rate and quality of life in liver transplant patients.

Primary antifungal prophylaxis in adult hematopoietic stem cell transplant recipients: current therapeutic concepts

In recipients of hematopoietic stem cell transplants (HSCTs), the mortality associated with invasive fungal infections (IFIs) remains high, despite the introduction of broad-spectrum antifungal agents over the past 2 decades. Preventing exposure to fungal pathogens in this population is impossible; therefore, clinicians have focused on prophylactic use of antifungal agents to prevent IFIs in high-risk HSCT recipients. It is important to target antifungal prophylaxis by type of HSCT (autologous or allogeneic), local epidemiology, and risk factors for IFIs so that patients can receive the most appropriate agent while balancing costs and the risks of toxicity, and minimizing the development of resistance. To assist clinicians in weighing the pros and cons of currently available antifungal agents when choosing a suitable prophylactic regimen, we provide a review of several key prospective randomized trials that evaluated various antifungal agents for primary prophylaxis in adult HSCT recipients. In addition, we describe the epidemiology of and risk factors for IFIs in HSCT recipients, the difficulties in diagnosing IFIs, antifungal agents used for prophylaxis, and the goals of primary prophylaxis. Fluconazole remains the gold standard for primary prophylaxis in autologous HSCT recipients. For allogeneic HSCT recipients, the agent chosen for prophylaxis must be based on the patient's risk factors for IFIs. In low-risk patients, fluconazole is an appropriate agent to use for primary prophylaxis immediately after transplantation. However, in allogeneic HSCT recipients who develop complications, such as graft failure, graft-versus-host disease, or cytomegalovirus infection, prophylaxis with a mould-active agent should be used.

High diversity of extended-spectrum beta-lactamases in Escherichia coli isolates from Italian broiler flocks

We characterized 67 Escherichia coli isolates with reduced susceptibility to cefotaxime or ceftiofur obtained from healthy broilers housed in five Italian farms. The bla(CTX-M-1), bla(CTX-M-32) and bla(SHV-12) beta-lactamase genes were identified on IncI1, IncN, or IncFIB plasmids. Considerable genetic diversity was detected among the extended-spectrum beta-lactamase (ESBL)-producing isolates, and we identified indistinguishable strains in unrelated farms and indistinguishable plasmids in genetically unrelated strains. The detection of highly mobile plasmids suggests a potential animal reservoir for beta-lactamase genes.

[Invasive pulmonary aspergillosis in a hematooncological patient in the intensive care units. A review of the literature]

Invasive aspergillosis is a common condition in patients with hematologic malignancies. Symptoms are extremely non-specific, and therefore it is necessary to be familiar with the diagnostic tests for early diagnosis. This review has attempted to clarify the current evidence regarding the following areas: clinical presentation, methods of study and treatment of this condition in hemato-oncological critical patients.

Antifungal prophylaxis in liver transplant recipients

Although the overall incidence of fungal infections in liver transplant recipients has declined, these infections still contribute significantly to the morbidity and mortality of patients with risk factors for infection. Although antifungal prophylaxis has been widely studied and practiced, no consensus exists on which patients should receive prophylaxis, with which agent, and for what duration. Numerous studies have attempted to ascertain independent risk factors for invasive fungal infections in liver transplant patients, and these data, in addition to clinical trials, identify several patient groups at exceedingly high risk of fungal infection. These include retransplant patients, patients with renal failure requiring hemodialysis or renal replacement therapy, and those requiring reoperations after transplant. Because the majority of infections occur in the first month after transplantation, prophylaxis should be continued for 4-6 weeks. However, local epidemiology and research should guide decisions regarding choice of agent as well as overall development of interinstitutional guidelines, because the incidence and spectrum of infection may differ dramatically among institutions. Liver Transpl 15:842-858, 2009. (c) 2009 AASLD.

Respiratory infections in immunocompromised patients

PURPOSE OF REVIEW

Immunosuppressive states and therapies are becoming common in clinical practice. Recent advances and trends in bacterial, fungal, viral and parasitic pulmonary infections in immunosuppressed patients are described.

RECENT FINDINGS

Pulmonary infections can jeopardize the prognosis of immunosuppressed patients. The number of patients infected with multidrug-resistant bacteria or opportunistic pathogens like rapid-growing environmental mycobacteria, Strongyloides stercoralis or Rhodococcus equi is increasing with the increased numbers of immunosuppressed patients due to HIV/AIDS and the potent immunosuppressive therapies used in solid-organ and haematopoietic transplantations, cancer and systemic illnesses. The slow development of more effective antibiotics underlines the necessity of preventive measures, development of rapid detection tests for pathogens and appropriate treatment regimens to avoid development of further resistance.

SUMMARY

Adequate prophylaxis, clinical suspicion, microbiological and molecular investigations, drug susceptibility-based antibiotic treatment and new drug development are strategies required to face up to the challenge of pulmonary infections in immunodepressed patients.

Real-time and semiquantitative RT-PCR methods to analyze gene expression patterns during Aspergillus-host interactions

Aspergillus species are infamous for causing several plant and animal diseases that directly (e.g., invasive aspergillosis) or indirectly (e.g., consumption of toxic food supplies) can lead to high rates of morbidity in humans and animals worldwide. Despite progress in molecular information and manipulation of Aspergillus spp., including genome sequence availability and suitable transformation methodologies, efforts to control Aspergillus diseases are still far from satisfactory, due in part to lack of knowledge of fungal virulence attributes. In order to obtain meaningful insights on the disease mechanism(s), it is essential to detect virulence gene expression during host invasion. Here, we describe two PCR-based detection methods of Aspergillus gene expression in both plant and mammalian tissues. Moreover, these techniques can be employed for routine screening of large numbers of aspergilli to improve diagnosis, disease monitoring, and therapy of fungal disease.

Transmission of IncN plasmids carrying blaCTX-M-1 between commensal Escherichia coli in pigs and farm workers

CTX-M-1-producing Escherichia coli were isolated from 56 pigs, three farm personnel, two manure samples, and two air samples from two Danish pig farms where an association between prophylactic ceftiofur use and the occurrence of cephalosporin resistance was previously demonstrated. Human, animal, and environmental strains displayed high genetic diversity but harbored indistinguishable or closely related IncN plasmids carrying bla(CTX-M-1), indicating that IncN plasmids mediating cephalosporin resistance were transmitted between pigs and farm workers across multiple E. coli lineages.

Genes differentially expressed in conidia and hyphae of Aspergillus fumigatus upon exposure to human neutrophils

BACKGROUND

Aspergillus fumigatus is the most common etiologic agent of invasive aspergillosis in immunocompromised patients. Several studies have addressed the mechanism involved in host defense but only few have investigated the pathogen's response to attack by the host cells. To our knowledge, this is the first study that investigates the genes differentially expressed in conidia vs hyphae of A. fumigatus in response to neutrophils from healthy donors as well as from those with chronic granulomatous disease (CGD) which are defective in the production of reactive oxygen species.

METHODOLOGY/PRINCIPAL FINDINGS

Transcriptional profiles of conidia and hyphae exposed to neutrophils, either from normal donors or from CGD patients, were obtained by using the genome-wide microarray. Upon exposure to either normal or CGD neutrophils, 244 genes were up-regulated in conidia but not in hyphae. Several of these genes are involved in the degradation of fatty acids, peroxisome function and the glyoxylate cycle which suggests that conidia exposed to neutrophils reprogram their metabolism to adjust to the host environment. In addition, the mRNA levels of four genes encoding proteins putatively involved in iron/copper assimilation were found to be higher in conidia and hyphae exposed to normal neutrophils compared to those exposed to CGD neutrophils. Deletants in several of the differentially expressed genes showed phenotypes related to the proposed functions, i.e. deletants of genes involved in fatty acid catabolism showed defective growth on fatty acids and the deletants of iron/copper assimilation showed higher sensitivity to the oxidative agent menadione. None of these deletants, however, showed reduced resistance to neutrophil attack.

CONCLUSION

This work reveals the complex response of the fungus to leukocytes, one of the major host factors involved in antifungal defense, and identifies fungal genes that may be involved in establishing or prolonging infections in humans.

Development and optimization of quantitative PCR for the diagnosis of invasive aspergillosis with bronchoalveolar lavage fluid

Background

The diagnosis of invasive pulmonary aspergillosis (IPA) remains challenging. Culture and histopathological examination of bronchoalveolar lavage (BAL) fluid are useful but have suboptimal sensitivity and in the case of culture may require several days for fungal growth to be evident. Detection of Aspergillus DNA in BAL fluid by quantitative PCR (qPCR) offers the potential for earlier diagnosis and higher sensitivity. It is important to adopt quality control measures in PCR assays to address false positives and negatives which can hinder accurate evaluation of diagnostic performance.

Methods

BAL fluid from 94 episodes of pneumonia in 81 patients was analyzed. Thirteen episodes were categorized as proven or probable IPA using Mycoses Study Group criteria. The pellet and the supernatant fractions of the BAL were separately assayed. A successful extraction was confirmed with a human 18S rRNA gene qPCR. Inhibition in each qPCR was measured using an exogenous DNA based internal amplification control (IAC). The presence of DNA from pathogens in the Aspergillus genus was detected using qPCR targeting fungal 18S rRNA gene.

Results

Human 18S rRNA gene qPCR confirmed successful DNA extraction of all samples. IAC detected some degree of initial inhibition in 11 samples. When culture was used to diagnose IPA, the sensitivity and specificity were 84.5% and 100% respectively. Receiver-operating characteristic analysis of qPCR showed that a cutoff of 13 fg of Aspergillus genomic DNA generated a sensitivity, specificity, positive and negative predictive value of 77%, 88%, 50%, 96% respectively. BAL pellet and supernatant analyzed together resulted in sensitivity and specificity similar to BAL pellet alone. Some patients did not meet standard criteria for IPA, but had consistently high levels of Aspergillus DNA in BAL fluid by qPCR.

Conclusion

The Aspergillus qPCR assay detected Aspergillus DNA in 76.9% of subjects with proven or probable IPA when the concentrated BAL fluid pellet fraction was used for diagnosis. There was no benefit from analyzing the BAL supernatant fraction. Use of both extraction and amplification controls provided optimal quality control for interpreting qPCR results and therefore may increase our understanding of the true potential of qPCR for the diagnosis of IPA.