Invasive Fungal Infections in Inpatient Solid Organ Transplant Recipients With COVID-19: A Multicenter Retrospective Cohort.

BACKGROUND: The prevalence and outcomes of COVID-19-associated invasive fungal infections (CAIFIs) in solid organ transplant recipients (SOTRs) remain poorly understood. METHODS: A retrospective cohort study of SOTRs with COVID-19 admitted to 5 hospitals within Johns Hopkins Medicine was performed between March 2020 and March 2022. Cox regression multilevel mixed-effects ordinal logistic regression was used. RESULTS: In the cohort of 276 SOTRs, 22 (8%) developed IFIs. The prevalence of CAIFIs was highest in lung transplant recipients (20%), followed by recipients of heart (2/28; 7.1%), liver (3/46; 6.5%), and kidney (7/149; 4.7%) transplants. In the overall cohort, only 42 of 276 SOTRs (15.2%) required mechanical ventilation; these included 11 of 22 SOTRs (50%) of the CAIFI group and 31 of 254 SOTRs (12.2%) of the no-CAIFI group. Compared with those without IFIs, SOTs with IFIs had worse outcomes and required more advanced life support (high-flow oxygen, vasopressor, and dialysis). SOTRs with CAIFIs had higher 1-y death-censored allograft failure (hazard ratio 1.6 5.1 16.4 , P  = 0.006) and 1-y mortality adjusting for oxygen requirement (adjusted hazard ratio 1.1 2.4 5.1 , P  < 0.001), compared with SOTRs without CAIFIs. CONCLUSIONS: The prevalence of CAIFIs in inpatient SOTRs with COVID-19 is substantial. Clinicians should be alert to the possibility of CAIFIs in SOTRs with COVID-19, particularly those requiring supplemental oxygen, regardless of their intubation status.

Progressive disseminated histoplasmosis: The experience in one non-endemic medical center.

Histoplasmosis, the most common endemic mycosis in North America, presents in a myriad of ways, spanning the spectrum from self-limiting pneumonia to progressive disseminated histoplasmosis (PDH). Toward better describing contemporary histoplasmosis syndromes, risks, and outcomes, this single-center retrospective cohort study was performed (2009-2019). The population who developed PDH was similar to that with other forms of histoplasmosis (OFH) except for higher rates of preexisting immunocompromising conditions (91.3% vs. 40%, P < .001) and a trend toward receiving more chronic immunosuppression (65.2% vs. 33.3%, P = .054) compared to those with OFH. Diagnosis was most frequently achieved by urinary or serum antigen positivity. People with PDH more frequently tested positive compared to those with OFH, but negative tests did not rule out histoplasmosis. Median time to diagnosis was prolonged among people with both PDH and OFH (32 vs. 31 days, respectively). Following diagnosis, people with PDH received more liposomal amphotericin (78.3% vs. 20%, P < .001). Subsequent survival at 90 and 365 days and treatment response were similar in both groups. Patients with PDH were more often hospitalized (95.7% vs. 60%, P = .006); however, once admitted, there were no differences in hospital length of stay or intensive care unit admission rate. The challenges of diagnosing histoplasmosis based on clinical presentation alone highlight the need for heightened awareness of these entities especially given the recent reports on expanded endemicity and delays in diagnosis.

Histoplasmosis is the most common endemic mycosis in North America. This article summarizes the clinical features, risk factors, and outcomes in patients who developed disseminated disease compared to more localized forms of histoplasmosis.

Coronavirus Disease 2019-Associated Pulmonary Aspergillosis: A Noninvasive Screening Model for Additional Diagnostics.

Background: Coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) is likely underdiagnosed, and current diagnostic tools are either invasive or insensitive. Methods: A retrospective study of mechanically ventilated patients with COVID-19 admitted to 5 Johns Hopkins hospitals between March 2020 and June 2021 was performed. Multivariable logistic regression was used for the CAPA prediction model building. Performance of the model was assessed using the area under the receiver operating characteristic curve (AUC). Results: In the cohort of 832 patients, 98 (11.8%) met criteria for CAPA. Age, time since intubation, dexamethasone for COVID-19 treatment, underlying pulmonary circulatory diseases, human immunodeficiency virus, multiple myeloma, cancer, or hematologic malignancies were statistically significantly associated with CAPA and were included in the CAPA prediction model, which showed an AUC of 0.75 (95% confidence interval, .70-.80). At a screening cutoff of ≥0.085, it had a sensitivity of 82%, a specificity of 51%, a positive predictive value of 18.6%, and a negative predictive value of 95.3%. (The CAPA screening score calculator is available at www.transplantmodels.com). Conclusions: We developed a CAPA risk score as a noninvasive tool to aid in CAPA screening for patients with severe COVID-19. Our score will also identify a group of patients who are unlikely to have CAPA and who therefore need not undergo additional diagnostics and/or empiric antifungal therapy.

Development of an Interferon-Gamma Release Assay (IGRA) to Aid Diagnosis of Histoplasmosis.

Establishing diagnosis of latent and active histoplasmosis is challenging. Interferon gamma-release assays (IGRAs) may provide evidence of latent and active infection. An enzyme-linked immunospot (ELISpot) assay was developed using yeast cell lysate (YCL) antigen prepared from a representative North American Histoplasma capsulatum strain. Assay parameters were optimized by measuring responses in healthy volunteers with and without Histoplasma infection. Assay performance as an aid for diagnosing histoplasmosis was assessed in a prospective cohort of 88 people with suspected or confirmed infection, and 44 healthy controls enrolled in two centers in North America (2013 to 2018). Antigen specificity of IFN-γ release was demonstrated using ELISpot and enzyme-linked immunosorbent assay (ELISA). Antigen-evoked, single-cell mRNA expression by memory T cells was shown using flow cytometry. The area under the receiver operating characteristic curve (AUC) was estimated at 0.89 (95% confidence interval [CI]: 78.5% to 99.9%). At optimal cutoff, sensitivity was 77.2% (95% CI: 54.6% to 92.2%) and specificity was 100% (95% CI: 89.7% to 100%). Sixteen of 44 healthy volunteers (36.4%) from a region of hyperendemicity had positive responses, suggesting detection of previously unrecognized (latent) infection. The ELISpot assay is sensitive and specific as an aid to diagnose H. capsulatum infection and disease, supporting proof of concept and further development.

Aspergillosis Complicating Severe Coronavirus Disease.

Aspergillosis complicating severe influenza infection has been increasingly detected worldwide. Recently, coronavirus disease-associated pulmonary aspergillosis (CAPA) has been detected through rapid reports, primarily from centers in Europe. We provide a case series of CAPA, adding 20 cases to the literature, with review of pathophysiology, diagnosis, and outcomes. The syndromes of pulmonary aspergillosis complicating severe viral infections are distinct from classic invasive aspergillosis, which is recognized most frequently in persons with neutropenia and in other immunocompromised persons. Combined with severe viral infection, aspergillosis comprises a constellation of airway-invasive and angio-invasive disease and results in risks associated with poor airway fungus clearance and killing, including virus- or inflammation-associated epithelial damage, systemic immunosuppression, and underlying lung disease. Radiologic abnormalities can vary, reflecting different pathologies. Prospective studies reporting poor outcomes in CAPA patients underscore the urgent need for strategies to improve diagnosis, prevention, and therapy.

Development and Evaluation of a Fully Automated Molecular Assay Targeting the Mitochondrial Small Subunit rRNA Gene for the Detection of Pneumocystis jirovecii in Bronchoalveolar Lavage Fluid Specimens.

The fungal pathogen Pneumocystis jirovecii causes Pneumocystis pneumonia. Although the mitochondrial large subunit rRNA gene (mtLSU) is commonly used as a PCR target, a mitochondrial small subunit rRNA gene (mtSSU)-targeted MultiCode PCR assay was developed on the fully automated ARIES platform for detection of P. jirovecii in bronchoalveolar lavage fluid specimens in 2.5 hours. The assay showed a limit of detection of 800 copies/mL (approximately equal to 22 organisms/mL), with no cross-reactivity with other respiratory pathogens. Compared with the reference Pneumocystis-specific direct fluorescent antibody assay (DFA) and mtLSU-targeted PCR assay, the new assay demonstrated sensitivity of 96.9% (31/32) and specificity of 94.6% (139/147) in detecting P. jirovecii in 180 clinical bronchoalveolar lavage fluid specimens. This assay was concordant with all DFA-positive samples and all but one mtLSU PCR-positive sample, and detected eight positive samples that were negative by DFA and mtLSU PCR. Receiver operating characteristic curve analysis revealed an area under the curve of 0.98 and a threshold cycle (CT) cutoff of 39.1 with sensitivity of 90.9% and specificity of 99.3%. The detection of 39.1

A Multicenter, Longitudinal Cohort Study of Cryptococcosis in Human Immunodeficiency Virus-negative People in the United States.

BACKGROUND: Cryptococcosis is increasingly recognized in people without human immunodeficiency virus (HIV). METHODS: A multicenter, prospective cohort study was performed in 25 US centers. Consenting patients were prospectively followed for ≤2 years. Neurological morbidities were assessed with longitudinal event depiction and functional scores (Montreal Cognitive Assessment [MoCA]). Risks of death were analyzed using Cox regression. RESULTS: One hundred forty-five subjects were enrolled. Most were male (95; 65.5%) and had immunosuppression (120; 82.8%), including solid organ transplant (SOT; 33.8%), autoimmunity (15.9%), and hematologic malignancies (11.7%). Disease involved the central nervous system (CNS) in 71 subjects (49%). Fever was uncommon, documented in 40 (27.8%) subjects, and absence was associated with diagnostic delay (mean: 48.2 vs 16.5 days; P = .007). Abnormal MoCA scores (<26) were predictive of CNS disease; low scores (<22) were associated with poor long-term cognition. Longitudinal event depiction demonstrated frequent complications in people with CNS disease; 25 subjects (35.2%) required >1 lumbar puncture and 8 (11.3%) required ventriculostomies. In multivariable models, older age (>60 years) was associated with higher risks of death (hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.05-4.38; P = .036), and lower risks were noted with underlying hematologic malignancy (HR, 0.29; 95% CI, 0.09-0.98; P = .05) and prior SOT (HR, 0.153; 95% CI, 0.05-0.44; P = .001). CONCLUSIONS: Despite aggressive antifungal therapies, outcomes of CNS cryptococcosis in people without HIV are characterized by substantial long-term neurological sequelae. Studies are needed to understand mechanism(s) of cognitive decline and to enable better treatment algorithms.

Long-term risk of hepatocellular carcinoma mortality in 23220 hospitalized patients treated with micafungin or other parenteral antifungals.

BACKGROUND: Liver tumours observed in rats exposed to micafungin led to a black box warning upon approval in Europe in 2008. Micafungin's risk for liver carcinogenicity in humans has not been investigated. We sought to describe the risk of fatal hepatocellular carcinoma (HCC) among persons who received micafungin and other parenteral antifungals (PAFs) with up to 12 years of follow-up. METHODS: We assembled a US multicentre cohort of hospitalized patients who received micafungin or other PAFs between 2005 and 2012. We used propensity score (PS) matching on patient characteristics from electronic medical records to compare rates of HCC mortality identified through the National Death Index though to the end of December 2016. We computed HRs and 95% CIs. RESULTS: A total of 40110 patients who received a PAF were identified; 6903 micafungin recipients (87% of those identified) were successfully matched to 16317 comparator PAF users. Ten incident HCC deaths, one in the micafungin-exposed group and nine among comparator PAF users, occurred in 71285 person-years of follow-up. The HCC mortality rate was 0.05 per 1000 person-years in micafungin patients and 0.17 per 1000 person-years in comparator PAF patients. The PS-matched HR for micafungin versus comparator PAF was 0.29 (95% CI 0.04-2.24). CONCLUSIONS: Both micafungin and comparator PAFs were associated with HCC mortality rates of <0.2 per 1000 person-years. Given the very low event rates, any potential risk for HCC should not play a role in clinical decisions regarding treatment with micafungin or other PAFs investigated in this study.

Urine Antigen Detection as an Aid to Diagnose Invasive Aspergillosis.

Background: Establishing rapid diagnoses of invasive aspergillosis (IA) is a priority tests that detect galactomannan and ß-d-glucan are available, but are technically cumbersome and rely on invasive sampling (blood or bronchoalveolar lavage). Methods: We optimized a lateral flow dipstick assay using the galactofuranose-specific monoclonal antibody (mAb476), which recognizes urine antigens after Aspergillus fumigatus pulmonary infection in animals. Urine samples were obtained from a cohort of 78 subjects undergoing evaluation for suspected invasive fungal infections, and stored frozen until testing. Urine was processed by centrifugation through desalting columns and exposed to dipsticks. Reviewers blinded to clinical diagnoses graded results. Western blots were performed on urine samples from 2 subjects to characterize mAb476-reactive antigens. Results: Per-patient sensitivity and specificity for diagnosis of proven or probable IA in the overall cohort was 80% (95% confidence interval [CI], 61.4%-92.3%) and 92% (95% CI, 74%-99%), respectively. In the subgroup with cancer, sensitivity was 89.5% (95% CI, 66.7%-98.7%) and specificity was 90.9% (95% CI, 58.7%-99.8%); among all others, sensitivity and specificity were 63.6% (95% CI, 30.8%-89.1%) and 92.9% (95% CI, 66.1%-99.8%), respectively. Eliminating lung transplant recipients with airway disease increased sensitivity in the noncancer cohort (85.7% [95% CI, 42.1%-99.6%]). Semiquantitative urine assay results correlated with serum galactomannan indices. Western blots demonstrated mAb476-reactive antigens in urine from cases, ranging between 26 kDa and 35 kDa in size. Conclusions: Urine testing using mAb476 may be used as an aid to diagnose IA in high-risk patients.

Short-term risk of liver and renal injury in hospitalized patients using micafungin: a multicentre cohort study.

BACKGROUND: Although echinocandins are generally well tolerated, there is little information on the frequency with which renal and hepatic adverse effects occur during use of micafungin or other parenteral antifungal (PAF) agents in clinical practice. METHODS: MYCOS is a multicentre cohort study of adult and paediatric patients who received micafungin or other PAFs between 2005 and 2012 at seven tertiary care hospitals from six centres in the USA. PAF cohort controls were selected through propensity score (PS) matching to micafungin recipients using clinical characteristics, other treatments, procedures and hospital service where PAF treatment was initiated. Analysis was restricted to patients without chronic liver and kidney conditions at the time of cohort entry. Treatment-emergent hepatic and renal injury was documented by changes in liver enzymes or estimated glomerular filtration rate through 30 days following completion of PAF treatment. Comparisons were quantified using the HR from a proportional hazards analysis. RESULTS: There were 2970 micafungin recipients PS matched to 6726 recipients of comparator PAFs. Balance was achieved in all baseline covariates between treatment groups. There were similar rates of hepatic injury (micafungin, 13 events per 100 patients and other PAF, 12 per 100; HR = 0.99; 95% CI 0.86-1.14) and lower rates of renal injury (micafungin, 63 events per 100 patients and other PAF, 65 per 100; HR = 0.93; 95% CI 0.87-0.99) for micafungin recipients versus PAF comparators. CONCLUSION: For a wide spectrum of underlying conditions, we observed no increase in liver injury by micafungin and possibly a reduced risk of renal dysfunction in comparison with other PAF medications.

Immunotherapy of Fungal Infections.

Fungal organisms are ubiquitous in the environment. Pathogenic fungi, although relatively few in the whole gamut of microbial pathogens, are able to cause disease with varying degrees of severity in individuals with normal or impaired immunity. The disease state is an outcome of the fungal pathogen's interactions with the host immunity, and therefore, it stands to reason that deep/invasive fungal diseases be amenable to immunotherapy. Therefore, antifungal immunotherapy continues to be attractive as an adjunct to the currently available antifungal chemotherapy options for a number of reasons, including the fact that existing antifungal drugs, albeit largely effective, are not without limitations, and that morbidity and mortality associated with invasive mycoses are still unacceptably high. For several decades, intense basic research efforts have been directed at development of fungal immunotherapies. Nevertheless, this approach suffers from a severe bench-bedside disconnect owing to several reasons: the chemical and biological peculiarities of the fungal antigens, the complexities of host-pathogen interactions, an under-appreciation of the fungal disease landscape, the requirement of considerable financial investment to bring these therapies to clinical use, as well as practical problems associated with immunizations. In this general, non-exhaustive review, we summarize the features of ongoing research efforts directed towards devising safe and effective immunotherapeutic options for mycotic diseases, encompassing work on antifungal vaccines, adoptive cell transfers, cytokines, antimicrobial peptides (AMPs), monoclonal antibodies (mAbs), and other agents.

Phenotyping mouse pulmonary function in vivo with the lung diffusing capacity.

The mouse is now the primary animal used to model a variety of lung diseases. To study the mechanisms that underlie such pathologies, phenotypic methods are needed that can quantify the pathologic changes. Furthermore, to provide translational relevance to the mouse models, such measurements should be tests that can easily be done in both humans and mice. Unfortunately, in the present literature few phenotypic measurements of lung function have direct application to humans. One exception is the diffusing capacity for carbon monoxide, which is a measurement that is routinely done in humans. In the present report, we describe a means to quickly and simply measure this diffusing capacity in mice. The procedure involves brief lung inflation with tracer gases in an anesthetized mouse, followed by a 1 min gas analysis time. We have tested the ability of this method to detect several lung pathologies, including emphysema, fibrosis, acute lung injury, and influenza and fungal lung infections, as well as monitoring lung maturation in young pups. Results show significant decreases in all the lung pathologies, as well as an increase in the diffusing capacity with lung maturation. This measurement of lung diffusing capacity thus provides a pulmonary function test that has broad application with its ability to detect phenotypic structural changes with most of the existing pathologic lung models.

Niche-specific requirement for hyphal wall protein 1 in virulence of Candida albicans.

Specialized Candida albicans cell surface proteins called adhesins mediate binding of the fungus to host cells. The mammalian transglutaminase (TG) substrate and adhesin, Hyphal wall protein 1 (Hwp1), is expressed on the hyphal form of C. albicans where it mediates fungal adhesion to epithelial cells. Hwp1 is also required for biofilm formation and mating thus the protein functions in both fungal-host and self-interactions. Hwp1 is required for full virulence of C. albicans in murine models of disseminated candidiasis and of esophageal candidiasis. Previous studies correlated TG activity on the surface of oral epithelial cells, produced by epithelial TG (TG1), with tight binding of C. albicans via Hwp1 to the host cell surfaces. However, the contribution of other Tgs, specifically tissue TG (TG2), to disseminated candidiasis mediated by Hwp1 was not known. A newly created hwp1 null strain in the wild type SC5314 background was as virulent as the parental strain in C57BL/6 mice, and virulence was retained in C57BL/6 mice deleted for Tgm2 (TG2). Further, the hwp1 null strains displayed modestly reduced virulence in BALB/c mice as did strain DD27-U1, an independently created hwp1Δ/Δ in CAI4 corrected for its ura3Δ defect at the URA3 locus. Hwp1 was still needed to produce wild type biofilms, and persist on murine tongues in an oral model of oropharyngeal candidiasis consistent with previous studies by us and others. Finally, lack of Hwp1 affected the translocation of C. albicans from the mouse intestine into the bloodstream of mice. Together, Hwp1 appears to have a minor role in disseminated candidiasis, independent of tissue TG, but a key function in host- and self-association to the surface of oral mucosa.

Detection of urinary excreted fungal galactomannan-like antigens for diagnosis of invasive aspergillosis.

Mortality associated with invasive aspergillosis (IA) remains high, partly because of delayed diagnosis. Detection of microbial exoantigens, released in serum and other body fluids during infection, may help timely diagnosis. In course of IA, Aspergillus galactomannan (GM), a well established polysaccharide biomarker, is released in body fluids including urine. Urine is an abundant, safely collected specimen, well-suited for point-of-care (POC) testing, which could play an increasing role in screening for early disease. Our main objective was to demonstrate GM antigenuria as a clinically relevant biological phenomenon in IA and establish proof-of-concept that it could be translated to POC diagnosis. Utilizing a novel IgM monoclonal antibody (MAb476) that recognizes GM-like antigens from Aspergillus and other molds, we demonstrated antigenuria in an experimental animal IA model (guinea pig), as well as in human patients. In addition, we investigated the chemical nature of the urinary excreted antigen in human samples, characterized antigen detection in urine by immunoassays, described a putative assay inhibitor in urine, and indicated means of alleviation of the inhibition. We also designed and used a lateral flow immunochromatographic assay to detect urinary excreted antigen in a limited number of IA patient urine samples. In this study, we establish that POC diagnosis of IA based on urinary GM detection is feasible. Prospective studies will be necessary to establish the performance characteristics of an optimized device and define its optimal clinical use.

Cystic fibrosis transmembrane conductance regulator regulates epithelial cell response to Aspergillus and resultant pulmonary inflammation.

RATIONALE: Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) alter epithelial cell (EC) interactions with multiple microbes, such that dysregulated inflammation and injury occur with airway colonization in people with cystic fibrosis (CF). Aspergillus fumigatus frequently colonizes CF airways, but it has been assumed to be an innocent saprophyte; its potential role as a cause of lung disease is controversial. OBJECTIVES: To study the interactions between Aspergillus and EC, and the role of the fungus in evoking inflammatory responses. METHODS: A. fumigatus expressing green fluorescent protein was developed for in vitro and in vivo models, which used cell lines and mouse tracheal EC. MEASUREMENTS AND MAIN RESULTS: Fungal spores (conidia) are rapidly ingested by ECs derived from bronchial cell lines and murine tracheas, supporting a role for EC in early airway clearance. Bronchial ECs harboring CFTR mutations (ΔF508) or deletion demonstrate impaired uptake and killing of conidia, and ECs with CFTR mutation undergo more conidial-induced apoptosis. Germinated (hyphal) forms of the fungus evoke secretion of inflammatory mediators, with CFTR mutation resulting in increased airway levels of macrophage inflammatory protein 2 and KC, and higher lung monocyte chemotactic protein-1. After A. fumigatus inhalation, CFTR(-/-) mice develop exaggerated lymphocytic inflammation, mucin accumulation, and lung injury. CONCLUSIONS: Data demonstrate a critical role for CFTR in mediating EC responses to A. fumigatus. Results suggest that the fungus elicits aberrant pulmonary inflammation in the setting of CFTR mutation, supporting the potential role of antifungals to halt progressive CF lung disease.

The absence of serum IgM enhances the susceptibility of mice to pulmonary challenge with Cryptococcus neoformans.

The importance of T cell-mediated immunity for resistance to the disease (cryptococcal disease) caused by Cryptococcus neoformans is incontrovertible, but whether Ab immunity also contributes to resistance remains uncertain. To investigate the role of IgM in resistance to C. neoformans, we compared the survival, fungal burden, lung and brain inflammatory responses, and lung phagocytic response of sIgM(-/-) mice, which lack secreted IgM, to that of IgM sufficient C57BL6x129Sv (heretofore, control) mice at different times after intranasal infection with C. neoformans (24067). sIgM(-/-) mice had higher mortality and higher blood and brain CFUs 28 d postinfection, but lung CFUs were comparable. Lungs of control mice manifested exuberant histiocytic inflammation with visible C. neoformans, findings that were not observed in sIgM(-/-) mice, whereas in brain sections, sIgM(-/-) mice had marked inflammation with visible C. neoformans that was not observed in control mice. Cytokine responses were significant for higher levels of lung IL-1beta and IL-12 24 h postinfection in control mice and higher levels of lung and brain IL-17 28 d postinfection in sIgM(-/-) mice. Alveolar macrophage phagocytosis was significantly higher for control than for sIgM(-/-) mice 24 h postinfection; however, phagocytic indices of sIgM(-/-) mice increased after reconstitution of sIgM(-/-) mice with polyclonal IgM. These data establish a previously unrecognized role for IgM in resistance to intranasal infection with C. neoformans in mice and suggest that the mechanism by which it mediates a host benefit is by augmenting Th1 polarization, macrophage recruitment and phagocytosis of C. neoformans.

Improved survival of mice deficient in secretory immunoglobulin M following systemic infection with Cryptococcus neoformans.

Cryptococcus neoformans causes severe, and often fatal, disease (cryptococcosis) in immunocompromised patients, particularly in those with HIV/AIDS. Although resistance to cryptococcosis requires intact T-cell immunity, a possible role for antibody/B cells in protection against natural disease has not been definitively established. Previous studies of the antibody response to the C. neoformans capsular polysaccharide glucuronoxylomannan (GXM) have demonstrated that patients who are at increased risk for cryptococcosis have lower serum levels of GXM-reactive IgM than those who are not at risk, leading to the hypothesis that IgM might contribute to resistance to cryptococcosis. To determine the influence of IgM on susceptibility to systemic cryptococcosis in a murine model, we compared the survival of mice deficient in serum IgM (secretory IgM deficient [sIgM(-/-)]) and C57BL/6 x 129Sv (control) mice after intraperitoneal infection with C. neoformans strain 24067 and analyzed the splenic B- and T-cell subsets by flow cytometry and the serum and splenic cytokine/chemokine and serum antibody profiles of each mouse strain. The results showed that sIgM(-/-) mice survived significantly longer than control mice when challenged with 10(5) CFU of C. neoformans 24067. Naïve sIgM(-/-) mice had higher levels of B-1 (CD5(+)) B cells, proinflammatory mediators (interleukin-6 [IL-6], IL-1beta, MIP-1beta, tumor necrosis factor alpha [TNF-alpha], and gamma interferon [IFN-gamma]), and anti-inflammatory mediators (IL-10 and IL-13) and significantly higher titers of GXM-specific IgG2a 3 weeks postinfection. In addition, CD5(+) splenocytes from both mouse strains had fungicidal activity against C. neoformans. Taken together, these results suggest that the inflammatory milieu in sIgM(-/-) mice might confer enhanced resistance to systemic cryptococcosis, stemming in part from the antifungal activity of B-1 B cells.

Spread of Cryptococcus gattii into Pacific Northwest region of the United States.

Cryptococcus gattii has emerged as a human and animal pathogen in the Pacific Northwest. First recognized on Vancouver Island, British Columbia, Canada, it now involves mainland British Columbia, and Washington and Oregon in the United States. In Canada, the incidence of disease has been one of the highest worldwide. In the United States, lack of cryptococcal species identification and case surveillance limit our knowledge of C. gattii epidemiology. Infections in the Pacific Northwest are caused by multiple genotypes, but the major strain is genetically novel and may have emerged recently in association with unique mating or environmental changes. C. gattii disease affects immunocompromised and immunocompetent persons, causing substantial illness and death. Successful management requires an aggressive medical and surgical approach and consideration of potentially variable antifungal drug susceptibilities. We summarize the study results of a group of investigators and review current knowledge with the goal of increasing awareness and highlighting areas where further knowledge is required.

Cryptococcus gattii: Emergence in Western North America: Exploitation of a Novel Ecological Niche.

The relatively uncommon fungal pathogen Cryptococcus gattii recently emerged as a significant cause of cryptococcal disease in human and animals in the Pacific Northwest of North America. Although genetic studies indicated its possible presence in the Pacific Northwest for more than 30 years, C. gattii as an etiological agent was largely unknown in this region prior to 1999. The recent emergence may have been encouraged by changing conditions of climate or land use and/or host susceptibility, and predictive ecological niche modeling indicates a potentially wider spread. C. gattii can survive wide climatic variations and colonize the environment in tropical, subtropical, temperate, and dry climates. Long-term climate changes, such as the significantly elevated global temperature in the last 100 years, influence patterns of disease among plants and animals and create niche microclimates habitable by emerging pathogens. C. gattii may have exploited such a hitherto unrecognized but clement environment in the Pacific Northwest to provide a wider exposure and risk of infection to human and animal populations.