Deep infections caused by Scedosporium prolificans. A report on 16 cases in Spain and a review of the literature. Scedosporium Prolificans Spanish Study Group

Epidemiology of invasive fungal infection

Invasive fungal infection is a growing cause of morbidity and mortality in immunosuppressed patients. Furthermore, the use of azole prophylaxis against Candida species has coincided with an increase in the incidence of invasive aspergillosis and infections by other filamentous fungi such as Mucorales. New risk factors and different timescales for onset have been identified. Knowledge of changes in the epidemiology of, and risk factors for, invasive fungal infection is particularly important when developing therapeutic strategies and effective prophylaxis to improve the prognosis of immunosuppressed patients.

Host immune response against Scedosporium species

Scedosporium apiospermum and Scedosporium prolificans cause therapy-refractory infections in immunocompromised and immunocompetent hosts. While innate immune response is believed to be critical for the host defense against these fungi, its role has only recently been elucidated. Undefined pathogen-associated molecular patterns on the surface of conidia and hyphae are recognized by pattern-recognition receptors (PRRs) on the membrane of phagocytes, and the signal is transmitted intracellularly. PRRs that are important in the recognition of both fungal species are human Toll-like receptors (or Toll receptors in Drosophila melanogaster) and dectin-1. These induce signals responsible for the activation of genes leading to an effective host defense, especially those encoding pro-inflammatory cytokines. Both species are efficiently phagocytosed and elicit an oxidative burst by neutrophils and monocytes. While cytokines, such as interleukin-15, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor and interferon-gamma, have been found in vitro to variably modulate antifungal activity of human phagocytes, cytokines in vivo activities are less well documented. Certain antifungal agents exert immunopharmacological effects on phagocytes against S. apiospermum and S. prolificans. Translation of these in vitro findings to appropriate in vivo systems and into clinical trials may lead to improved strategies for augmenting innate host defenses in patients infected with these emerging pathogens.

Scedosporium prolificans: an emerging pathogen in France?

For the last ten years, non-Aspergillus mold species have been increasingly involved in human invasive infections, probably as a consequence of more intense immunosuppression and prolonged patient survival, and of selective pressure since antifungal agents are currently used for prophylaxis or therapy. Scedosporium prolificans, one of these emerging fungi, has been isolated in a broad spectrum of clinical presentations in humans, including respiratory-tract colonization, superficial or locally invasive infections, and disseminated infections in immunocompromised patients. Here, we report the recent emergence of invasive infections due to S. prolificans in France, and describe four new cases diagnosed during the last six years. Only one disseminated scedosporiosis has been reported before this in France, in 1994. Three out of our four cases were breakthrough infections in immunocompromised patients receiving posaconazole or voriconazole therapy. The aims of the present review were thus to gain a better understanding of scedosporiosis epidemiology and clinical features, and to review recent advances in multimodal management of these infections, including surgery, recovery and/or enhancement of immunity, and antifungal combinations, especially voriconazole plus terbinafine.

Bloodstream infections in haematology: risks and new challenges for prevention

Bloodstream infections are an important cause of morbidity and mortality in the haematology population, and may contribute to delayed administration of chemotherapy, increased length of hospitalisation, and increased healthcare expenditure. For gram-positive, gram-negative, anaerobic and fungal infections, specific risk factors are recognised. Unique host and environmental factors contributing to pathogenesis are acknowledged in this population. Trends in spectrum and antimicrobial susceptibility of pathogens are examined, and potential contributing factors are discussed. These include the widespread use of empiric antimicrobial therapy, increasingly intensive chemotherapeutic regimens, frequent use of central venous catheters, and local infection control practices. In addition, the risks and benefits of prophylaxis, and spectrum of endemic flora are identified as relevant factors within individual centres. Finally, challenges are presented regarding prevention, early detection, surveillance and prophylaxis. To reduce the rate and impact of bloodstream infections multifaceted and customised strategies are required within individual haematology units.

Development and validation of a quantitative PCR assay for diagnosis of scedosporiosis

Scedosporium apiospermum and Scedosporium prolificans are fungal pathogens that can cause severe human infections, including disseminated mycosis in immunocompromised patients. Two real-time PCR (RT-PCR) assays for the diagnosis of these species were developed and validated for the classification of clinical strains and for the detection of DNA in clinical samples by use of a murine model of invasive infection. A total of 14 clinical strains and 141 samples, including blood, serum, and lung samples from infected CD1 mice, were analyzed. Each RT-PCR methodology used a species-specific molecular beacon probe targeting a highly conserved region of the fungal ribosomal DNA gene. Results showed 100% specificity and a detection limit of 10 fg of DNA for both assays. The sensitivities for the S. prolificans-specific PCR assay were 100% for cultured clinical strains, 95.5% for lung tissues, 85% for serum, and 83.3% for blood. For S. apiospermum, the sensitivities were 100% for clinical strains and 97.2%, 81.8%, and 54.5% for lung tissues, serum, and blood, respectively. Both techniques can be useful for clinical diagnosis, and further studies are warranted.

Endocrine and metabolic manifestations of invasive fungal infections and systemic antifungal treatment

Systemic fungal infections are increasingly reported in immunocompromised patients with hematological malignancies, recipients of bone marrow and solid organ allografts, and patients with AIDS. Mycoses may infiltrate endocrine organs and adversely affect their function or produce metabolic complications, such as hypopituitarism, hyperthyroidism or hypothyroidism, pancreatitis, hypoadrenalism, hypogonadism, hypernatremia or hyponatremia, and hypercalcemia. Antifungal agents used for prophylaxis and/or treatment of mycoses also have adverse endocrine and metabolic effects, including hypoadrenalism, hypogonadism, hypoglycemia, dyslipidemia, hypernatremia, hypocalcemia, hyperphosphatemia, hyperkalemia or hypokalemia, and hypomagnesemia. Herein, we review how mycoses and conventional systemic antifungal treatment can affect the endocrine system and cause metabolic abnormalities. If clinicians are equipped with better knowledge of the endocrine and metabolic complications of fungal infections and antifungal therapy, they can more readily recognize them and favorably affect outcome.

Multiplex tandem PCR: a novel platform for rapid detection and identification of fungal pathogens from blood culture specimens

We describe the first development and evaluation of a rapid multiplex tandem PCR (MT-PCR) assay for the detection and identification of fungi directly from blood culture specimens that have been flagged as positive. The assay uses a short-cycle multiplex amplification, followed by 12 simultaneous PCRs which target the fungal internal transcribed spacer 1 (ITS1) and ITS2 region, elongation factor 1-alpha (EF1-alpha), and beta-tubulin genes to identify 11 fungal pathogens: Candida albicans, Candida dubliniensis, Candida glabrata, Candida guilliermondii, Candida krusei, Candida parapsilosis complex, Candida tropicalis, Cryptococcus neoformans complex, Fusarium solani, Fusarium species, and Scedosporium prolificans. The presence or absence of a fungal target was confirmed by melting curve analysis. Identification by MT-PCR correlated with culture-based identification for 44 (100%) patients. No cross-reactivity was detected in 200 blood culture specimens that contained bacteria or in 30 blood cultures without microorganisms. Fungi were correctly identified in five specimens with bacterial coinfection and in blood culture samples that were seeded with a mixture of yeast cells. The MT-PCR assay was able to provide rapid (<2 h), sensitive, and specific simultaneous detection and identification of fungal pathogens directly from blood culture specimens.

Infections caused by Scedosporium spp

Scedosporium spp. are increasingly recognized as causes of resistant life-threatening infections in immunocompromised patients. Scedosporium spp. also cause a wide spectrum of conditions, including mycetoma, saprobic involvement and colonization of the airways, sinopulmonary infections, extrapulmonary localized infections, and disseminated infections. Invasive scedosporium infections are also associated with central nervous infection following near-drowning accidents. The most common sites of infection are the lungs, sinuses, bones, joints, eyes, and brain. Scedosporium apiospermum and Scedosporium prolificans are the two principal medically important species of this genus. Pseudallescheria boydii, the teleomorph of S. apiospermum, is recognized by the presence of cleistothecia. Recent advances in molecular taxonomy have advanced the understanding of the genus Scedosporium and have demonstrated a wider range of species than heretofore recognized. Studies of the pathogenesis of and immune response to Scedosporium spp. underscore the importance of innate host defenses in protection against these organisms. Microbiological diagnosis of Scedosporium spp. currently depends upon culture and morphological characterization. Molecular tools for clinical microbiological detection of Scedosporium spp. are currently investigational. Infections caused by S. apiospermum and P. boydii in patients and animals may respond to antifungal triazoles. By comparison, infections caused by S. prolificans seldom respond to medical therapy alone. Surgery and reversal of immunosuppression may be the only effective therapeutic options for infections caused by S. prolificans.

Molecular typing of Australian Scedosporium isolates showing genetic variability and numerous S. aurantiacum

One hundred clinical isolates from a prospective nationwide study of scedosporiosis in Australia (2003-2005) and 46 additional isolates were genotyped by internal transcribed spacer-restriction fragment length polymorphism (ITS-RFLP) analysis, ITS sequencing, and M13 PCR fingerprinting. ITS-RFLP and PCR fingerprinting identified 3 distinct genetic groups. The first group corresponded to Scedosporium prolificans (n = 83), and the other 2 comprised isolates previously identified as S. apiospermum: one of these corresponded to S. apiospermum (n = 33) and the other to the newly described species S. aurantiacum (n = 30). Intraspecies variation was highest for S. apiospermum (58%), followed by S. prolificans (45%) and S. aurantiacum (28%) as determined by PCR fingerprinting. ITS sequence variation of 2.2% was observed among S. apiospermum isolates. No correlation was found between genotype of strains and their geographic origin, body site from which they were cultured, or colonization versus invasive disease. Twelve S. prolificans isolates from 2 suspected case clusters were examined by amplified fragment length polymorphism analysis. No specific clusters were confirmed.

Treatment of scedosporiosis with voriconazole: clinical experience with 107 patients

The efficacy of voriconazole in 107 patients with scedosporiosis was analyzed. Principal infection sites were the lungs/sinuses (24%), central nervous system (CNS) (20%), and bone (18%), while 21% of patients had disseminated infection. Solid organ transplantation (22%), hematological malignancy (21%), and surgery/trauma (15%) were the predominant underlying conditions. A successful therapeutic response was achieved in 57% of patients (median, 103 therapy days), with > 98% of those responding receiving > or = 28 days of therapy. Patients receiving primary therapy showed a 61% response versus 56% for the others. The best therapeutic responses were seen for skin/subcutaneous (91%) or bone (79%) infections, and the lowest for CNS infections (43%). Patients without major immune suppression (72%) or those with solid organ transplantation (63%) or various hematological conditions (60%) showed the best responses by underlying condition. Median known survival time was 133 days (therapy successes, 252 days; failures, 21 days). In all, 43 (40%) patients died, 73% due to scedosporiosis. Patients with Scedosporium prolificans infection had significantly reduced survival times (P = 0.0259) and were more likely to die from fungal infection (P = 0.002) than were Scedosporium apiospermum-infected patients. In a subset of 43 patients where voriconazole baseline MICs were available, response to voriconazole was higher for S. apiospermum-infected patients (54% response; MIC(50), 0.25 microg/ml) than for S. prolificans-infected patients (40% response; MIC(50), 4.0 microg/ml). Voriconazole demonstrated clinically useful activity in the treatment of both S. apiospermum and S. prolificans infections and was well tolerated.

Infection with Scedosporium apiospermum and S. prolificans, Australia

S. prolificans has become a major pathogen in immunocompromised patients.

Scedosporium apiospermum and S. prolificans are fungi of increasing clinical importance, particularly in persons with underlying diseases. We reviewed the records of 59 patients in Australia from whom Scedosporium spp. were isolated from June 30, 1997, through December 31, 2003. S. apiospermum was isolated predominantly from the respiratory tracts of 28 of 31 patients with underlying lung diseases and resulted in 2 infections and 1 death. The annual number of S. apiospermum isolates remained constant. S. prolificans was isolated from 28 patients only after November 1999. Eight patients with acute myeloid leukemia or hematopoietic stem cell transplants had invasive infection; 4 had fungemia and 6 died from infection. S. prolificans caused locally invasive infection in 2 immunocompetent patients and was found in the respiratory tract of 18 patients with underlying respiratory disease but did not cause fungemia or deaths in these patients. Scedosporium spp. showed distinct clinical and epidemiologic features.

[Spectrum and risk factors of invasive fungal infection]

In recent years, invasive fungal infection has become a growing problem in immunosuppressed patients. Simultaneously, changes in medical practice, such as the use of anti-Candida prophylaxis with azoles, has led to a shift in the epidemiology of these infections from Candida spp. to Aspergillus and other filamentous molds. Moreover, new risk factors for invasive fungal infection have been identified and the time of onset is different from that seen a decade ago. Recognition of these trends in patients receiving novel immunosuppressive regimens has important implications for the clinical management of fungal infection in this population.

Activity and post antifungal effect of chlorpromazine and trifluopherazine against Aspergillus, Scedosporium and zygomycetes

The phenothiazine compounds chlorpromazine and trifluopherazine are antipsychotic agents that exhibit antimicrobial activity against bacteria, some protozoa and yeasts. Data of activity against filamentous fungi are lacking. The in vitro activity and postantifungal effect (PAFE) of chlorpromazine and trifluopherazine was determined against Aspergillus species, zygomycetes and Scedosporium species. In vitro susceptibility testing was performed with CLSI M38A and the PAFE was determined with previously established methods. Both drugs inhibited the growth of all fungi tested at concentrations of 16 to 64 microg ml(-1). For Aspergillus species the mean PAFE was 3.7 and 4.7 h; for zygomycetes, 3.1 and 3.4 h; for Scedosporium, 4.3 and 5.3 h for chlorpromazine and trifluoroperazine respectively. These are the first drugs shown to induce PAFE against Scedosporium. We show that phenothiazine compounds have in vitro antifungal activity and exhibit PAFE against a broad range of filamentous fungal pathogens. Although the exact mechanism of action is unknown, further studies are needed to explore the clinical usefulness of phenothiazine compounds.

Imaging findings of pulmonary infection caused by Scedosporium prolificans in a deep immunocompromised patient’

Scedosporium prolificans is an emerging fungus that causes rapid progressive and disseminated infections in immunodepressed patients. We present a case of a 34-year-old woman with chronic myelogenous leukemia who received a bone marrow transplantation and suffered a sudden respiratory failure in +67 day. Chest radiographies showed growing bilateral patchy condensations. Computed Tomography depicted bilateral nodular condensation of alveolar space. S. prolificans was detected from sputum, but the patient died 72 h later. Imaging findings of lung scedosporiosis are nonspecific, but CT may provide a prompter diagnosis and allow to add newer antifungal treatments. This report presents the first imaging report of lung scedosporiosis.

Changing Epidemiology of Rare Mould Infections

There has been an increase in rare mould infections in recent decades. These infections have been reported primarily in severely immunocompromised patients. The emergence of these organisms is multifactorial and can be related to more intense immunosuppression, the prolonged survival of patients who have what were previously fatal diseases, and the selective pressure of broad spectrum antifungal agents used for prophylaxis or therapy. Among these rare mould infections, the Zygomycetes are the most commonly encountered, and in some institutions the increase in these organisms appears to be associated with the use of voriconazole. Aspergillus terreus, a species that is resistant to amphotericin B, and less frequently, A. ustus and A. lentulus, have been noted increasingly as causes of invasive aspergillosis in tertiary care centres in the US. Several species of Scedosporium with innate resistance to many antifungal agents have emerged as major causes of disseminated mould infections that are frequently very difficult to treat. Among patients who have haematological malignancies, are neutropenic or have received a haematopoietic stem cell transplant, infections due to Fusarium species respond poorly to many antifungal agents. Dematiaceous, or brown-black, fungi, most often associated with chronic localised infections, are now increasingly reported as a cause of disseminated infection in immunosuppressed hosts. Concomitant with the increased number of infections with these rare moulds, several new mould-active antifungal agents have been developed. The new expanded spectrum azole, voriconazole, has changed our approach to moulds such as S.apiospermum, Fusarium species and A. terreus that are amphotericin B resistant. Posaconazole, the most recently approved expanded spectrum azole, is the first drug in the azole class to show activity against the Zygomycetes and has proven extremely useful for step-down therapy after initial treatment with amphotericin B. It is not known whether posaconazole is effective as primary therapy for zygomycosis; the use of this agent for that purpose awaits clinical trials with the recently developed intravenous formulation of posaconazole.

Emerging Fungi

The hyalohyphomycetes (especially Fusarium spp) have emerged as significant pathogens in severely immunocompromised patients. Human infections by Fusarium spp can be superficial or limited to single organs in otherwise healthy patients. Such infections are rare and tend to respond well to therapy. By contrast, disseminated fusarial hyalohyphomycosis affects the immunocompromised host and frequently is fatal. Successful outcome is determined by the degree of immunosuppression and the extent of the infection. These infections may be suspected clinically on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy.

Treatment of invasive infections due to rare or emerging yeasts and moulds

Emerging fungal infections represent a serious problem in an immunocompromised host. Rapid developments in in vitro antifungal susceptibility testing and the availability of several new antifungal agents have provided excellent opportunities to treat infections that are caused by various Candida spp. and to some extend by Aspergillus spp. However, recently the epidemiology of fungal infections has significantly changed and several new pathogens have emerged. This article attempts to summarise the available data on the management of emerging infections with fungal infections that have recently gained importance. Updated recommendations on antifungal treatment are also discussed.

Subcutaneous infection with Pseudallescheria boydii in an immunocompromised patient

With the broad employment of immunosuppressive therapy, the incidence of Pseudallescheria boydii infections is rising. We report a first case of the localized subcutaneous P. boydii infection in a patient with microscopic polyangiitis. Favorable outcome related to the treatment with voriconazole adds to the growing body of evidence supporting the use of this particular agent in P. boydii infections.

Caspofungin and liposomal amphotericin B therapy of experimental murine scedosporiosis

Immunosuppressed mice were infected intravenously with conidia of Scedosporium prolificans. Treatment was begun 1 day later with liposomal amphotericin B, caspofungin, or both drugs initiated concurrently. Amphotericin B and caspofungin were each effective, but combined therapy did not appear to offer advantages over liposomal amphotericin B alone.

Voriconazole in the treatment of fungal osteomyelitis of the orbit in the immunocompromised host

Scedosporium apiospermum is an uncommon cause of fungal infection in the orbit and sinus. Morbidity and mortality rates in immunocompromised patients are high. We review the first case of Scedosporium apiospermum orbito-sinus infection that was successfully treated with the new antifungal agent voriconazole. We highlight the efficacy of this drug, particularly in the treatment of osteomyelitis of the orbit and sinus, which may lead to an improvement in survival rates after Scedosporium infection.

Non-Aspergillus Fungal Pneumonia in Transplant Recipients

Although species of Aspergillus and Candida account for most deeply invasive and life-threatening fungal infections, the past decades have seen a rise in the immunocompromised population. With this increase, additional fungi have emerged as important agents of morbidity and mortality. These opportunistic fungi are characterized by their ubiquitous presence in the environment, their ability to cause disease in immunosuppressed patients, and their diminished susceptibility to the currently available antifungal agents. Pneumonia, one aspect of a myriad of clinical manifestations caused by these fungal pathogens, is discussed in this article.

[In vitro susceptibility of fungal and yeast clinical isolates to itraconazole and voriconazole]

The interest on the in vitro susceptibility to itraconazole has recently increased due the availability of the intravenous formulation. In this study, comparative MICs of this antifungal with voriconazole were carried out in 62 clinical isolates of filamentous fungi and 100 yeasts isolates using the NCCLS microbroth methods described in M38-A and M27-A2 documents. A MIC90 of 0.125 micrograms per ml was observed for itraconazole and voriconazole against Aspergillus fumigatus. Higher susceptibility to itraconazole was found for the filamentous form of Sporotrhix schenckii (p = 0.001). Voriconazole was more effective against Scedosporium apiospermium while Scedosporium prolificans isolates were resistant to both azoles. Some isolates of Rhizopus stolonifer were susceptible to itraconazole and resistant to voriconazole, but without statistical significance. Susceptibility of nine species of Candida was similar for both triazoles used in this study. However, Candida glabrata was more susceptible to voriconazole. Some fluconazole-resistant Candida albicans isolates were susceptible to itraconazole and / or voriconazole. Cryptococcus neoformans was more susceptible to itraconazole than to voriconazole. Itraconazole and voriconazole showed very close in vitro activity against the tested fungal isolated, except against S. schenckii. In spite of this, there were some differences in susceptibility among isolates within the same fungal species.

Cerebral scedosporiosis: an emerging fungal infection in severe neutropenic patients: CT features and CT pathologic correlation

Scedosporium prolificans is an emerging opportunistic fungal agent encountered in severely neutropenic patients. The purpose of this paper is to describe the main cranial CT findings from a retrospective review of six patients (four men and two women, 18-66 years old) afflicted with disseminated infection by S. prolificans with neurological symptoms. They were severely neutropenic and presented with severe respiratory failure and conscience deterioration, with a subsequent 100% mortality. The final diagnosis was established by autopsy (performed in five patients) and blood culture findings. Cranial CT showed multiple low-density lesions in four patients without contrast enhancement located in the basal ganglia and corticomedullary junction. Autopsy findings of these lesions demonstrated necrosis and hyphae proliferation inside brain infarcts. Also, two of the patients had a subarachnoid hemorrhage, but angiography could not be performed. CT and autopsy findings were fairly similar to those encountered in cerebral aspergillosis; however, possibly because of its rapid and fatal evolution, no edema or ring enhancing lesions were encountered. Thus, Scedosporium can be included as a rare but possible cause of invasive fungal disseminated central nervous system infections in severely neutropenic patients.

Disseminated Scedosporium prolificans infection and survival of a child with acute lymphoblastic leukemia

Scedosporium prolificans is a saprophytic fungus responsible for an increasing number of infections among immunocompromised hosts. Historically, disseminated infection with this organism has resulted in death. We report on a pediatric patient who developed overwhelming S. prolificans sepsis after induction chemotherapy for acute lymphoblastic leukemia. She is well 18 months after the diagnosis of fungal sepsis and continues to receive chemotherapy for leukemia, which remains in remission.

Inteferon gamma and granulocyte–macrophage colony-stimulating factor augment the antifungal activity of human polymorphonuclear leukocytes againstScedosporiumspp.: comparison withAspergillusspp

While Aspergillus spp. have been the most frequent filamentous fungi causing infections in immunocompromised patients, Scedosporium spp. are emerging as life-threatening pathogens. We studied the effects of interferon gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or combined on the antifungal activities of human polymorphonuclear leukocytes (PMN) against Scedosporium apiospermum and Scedosporium prolificans. We paralleled these activities to those against Aspergillus fumigatus and Aspergillus flavus. Incubation of PMN with IFN-gamma and GM-CSF for 22 h enhanced PMN-induced hyphal damage of both Aspergillus spp. and S. prolificans (p < 0.05) but not of S. apiospermum. However, hyphae of S. apiospermum were damaged significantly more after incubation with PMN that had been treated with IFN-gamma and GM-CSF for 2 h. In addition, incubation of PMN with GM-CSF for 2 h enhanced PMN oxidative burst measured as superoxide anion (O2-) production in response to nonopsonized hyphae of A. flavus and Scedosporium spp. (p < 0.05). In contrast, after 2 h, IFN-gamma and GM-CSF alone did not enhance PMN O2- in response to opsonized hyphae of A. flavus and Scedosporium spp.; however, the combination of IFN-gamma and GM-CSF showed significant enhancement against these species. Thus, IFN-gamma and GM-CSF, particularly in combination, demonstrate a species- and time-dependent augmentation of PMN responses to Scedosporium spp.

Infections Due to Scedosporium apiospermum and Scedosporium prolificans in Transplant Recipients: Clinical Characteristics and Impact of Antifungal Agent Therapy on Outcome

BACKGROUND

Unique characteristics, impact of therapy with antifungal agents, and outcome of infections with Scedosporium species were assessed in transplant recipients.

METHODS

The patients comprised a total of 80 transplant recipients with Scedosporium infections, including 13 patients from our institutions (University of Pittsburgh Medical Center [Pittsburgh, PA], University of Maryland [Baltimore], Duke University Medical Center [Durham, NC], Emory University [Atlanta, GA], and Hospital Gregorio Maranon [Madrid, Spain]) and 67 reported in the literature. The transplant recipients were compared with 190 non-transplant recipients with scedosporiosis who were described in the literature.

RESULTS

Overall, 69% of the infections in hematopoietic stem cell transplant (HSCT) recipients and 53% of the infections in organ transplant recipients were disseminated. HSCT recipients, compared with organ transplant recipients, were more likely to have infections caused by Scedosporium prolificans (P=.045), to have an earlier onset of infection (P=.007), to be neutropenic (P<.0001), and to have fungemia (P=.04). Time elapsed from transplantation to Scedosporium infection in transplant recipients has increased in recent years (P=.002). The mortality rate among transplant recipients with scedosporiosis was 58%. In a logistic regression model using amphotericin B as comparison treatment, voriconazole was associated with a trend towards better survival (odds ratio [OR], 10.40; P=.08). Presence of disseminated infection (OR, 0.20; P=.03) predicted lower survival, and receipt of adjunctive surgery as treatment (OR, 5.52; P=.02) independently predicted a better survival in this model.

CONCLUSIONS

Scedosporium infections in transplant recipients were associated with a high rate of dissemination and a poor outcome overall. The use of newer triazole agents warrants consideration as a therapeutic modality for these infections.

Interaction of granulocyte colony-stimulating factor and high doses of liposomal amphotericin B in the treatment of systemic murine scedosporiosis

Because human infections by Scedosporium prolificans are difficult to treat and show a very poor outcome, new therapeutic strategies are needed. Liposomal amphotericin B (LAMB) (40 mg/kg/day) increased significantly the mean survival time in immunosuppressed mice compared with a control group (22.6 vs. 8.8 days). Amphotericin B deoxycholate (1.5 mg/kg/day) and granulocyte colony-stimulating factor (G-CSF) (300 microg/kg/day) were ineffective. The combination of LAMB (40 mg/kg/day) and G-CSF (150 or 300 microg/kg/day) did not improve the results obtained with LAMB alone.

Antifungal activities of posaconazole and granulocyte-macrophage colony-stimulating factor ex vivo and in mice with disseminated infection due to Scedosporium prolificans

Invasive infection due to Scedosporium prolificans is characterized by drug resistance and a high rate of mortality. The effects of posaconazole (POS), an investigational antifungal triazole, murine granulocyte-macrophage colony-stimulating factor (GM-CSF), and their combination against S. prolificans were evaluated ex vivo and in a newly developed murine model of disseminated infection due to this organism. When POS was combined with polymorphonuclear leukocytes from untreated or GM-CSF-treated mice (P < 0.01) ex vivo, it had increased activity in terms of the percentage of hyphal damage. Immunocompetent BALB/c mice were infected with 4 x 10(4) conidia of S. prolificans via the lateral tail vein. At 24 h postinfection the mice were treated with GM-CSF (5 microg/kg of body weight/day subcutaneously), POS (50 mg/kg/day by gavage), both agents, or saline only. Half of the brain, lung, liver, and kidney from each animal were cultured; and the other half of each organ was processed for histopathology. The mean survival times were 7.0 +/- 0.3 days for the controls, 7.4 +/- 0.4 days for POS-treated mice, 8.0 +/- 0.3 days for GM-CSF-treated mice (P = 0.08 compared with the results for the controls), and 7.3 +/- 0.3 days for POS-GM-CSF-treated mice. Fungal burdens (determined as the numbers of CFU per gram of tissue) were found in descending orders of magnitude in the kidneys, brains, livers, and lungs. The burdens were significantly reduced in the brains of GM-CSF-treated mice (P < 0.05) and the livers of POS-treated mice (P < 0.05). The numbers of lesions in the organs closely corresponded to the fungal burdens. GM-CSF tended to prolong survival (P = 0.08 compared with the results for the controls). While the combination of POS and GM-CSF showed enhanced activity ex vivo, it did not increase the activities of the two agents against this highly refractory filamentous fungus in mice.

Infections due to emerging and uncommon medically important fungal pathogens

The emergence of less common but medically important fungal pathogens contributes to the rate of morbidity and mortality, especially in the increasingly expanding population of immunocompromised patients. These pathogens include septate filamentous fungi (e.g., Fusarium spp., Scedosporium spp., Trichoderma spp.), nonseptate Zygomycetes, the endemic dimorphic pathogen Penicillium marneffei, and non-Cryptococcus, non-Candida pathogenic yeast (e.g., Trichosporon spp.). The medical community is thus called upon to acquire an understanding of the microbiology, epidemiology and pathogenesis of these previously uncommon pathogens in order to become familiar with the options for prevention and treatment.

Invasive infections caused by Blastoschizomyces capitatus and Scedosporium spp

Blastoschizomyces capitatus, Scedosporium prolificans and S. apiospermum are emerging fungal pathogens that may cause disseminated disease in neutropenic patients. They can present as fever resistant to antibiotics and to wide-spectrum antifungal agents, although they may involve almost every organ. The proportion of recovery from blood cultures is high and they are characteristically resistant to most antifungal agents. Prognosis is poor unless patients recover from neutropenia. Voriconazole has good in-vitro activity and is currently the drug of choice for these infections.

Molecular typing of clinical and environmental isolates of Scedosporium prolificans by inter-simple-sequence-repeat polymerase chain reaction

Invasive infections by Scedosporium prolificans have increased alarmingly in recent years, mainly in immunosuppressed patients. The epidemiology, pathogenesis and the natural habitat of this pathogen are practically unknown. Isolates of S. prolificans were distinguished from one another by inter-simple-sequence-repeat (ISSR) fingerprinting, a technique based on the high degree of polymorphism of the multisatellite genetic markers used. This technique was found useful for typing 84 isolates of S. prolificans from different countries and sources. The assemblage of S. prolificans isolates tested was extremely diverse, with 35 genotypes present. Several patients were found to have been infected or colonized by more than one strain. Overall, this technique facilitates the epidemiological study of S. prolificans infection.

Scedosporium prolificans osteomyelitis in an immunocompetent child treated with voriconazole and caspofungin, as well as locally applied polyhexamethylene biguanide

Scedosporium species are increasingly isolated from immunocompromised and immunocompetent patients. Unfortunately, Scedosporium infections are generally resistant to amphotericin B, and Scedosporium prolificans strains are particularly resistant to the antifungal agents now in use. We report here on an immunocompetent child with S. prolificans-associated osteomyelitis successfully treated with debridement, local irrigation with polyhexamethylene biguanide, and the systemic administration of voriconazole and caspofungin despite poor in vitro activity of voriconazole alone against the isolate. We also review the treatments and outcomes of 28 reported cases of osteomyelitis or septic arthritis caused by Scedosporium species in immunocompetent patients.

Opportunistic mycelial fungal infections in organ transplant recipients: emerging importance of non-Aspergillus mycelial fungi

To determine the spectrum and impact of mycelial fungal infections, particularly those due to non-Aspergillus molds, 53 liver and heart transplant recipients with invasive mycelial infections were prospectively identified in a multicenter study. Invasive mycelial infections were due to Aspergillus species in 69.8% of patients, to non-Aspergillus hyalohyphomycetes in 9.4%, to phaeohyphomycetes in 9.4%, to zygomycetes in 5.7%, and to other causes in 5.7%. Infections due to mycelial fungi other than Aspergillus species were significantly more likely to be associated with disseminated (P=.005) and central nervous system (P=.07) infection than were those due to Aspergillus species. Overall mortality at 90 days was 54.7%. The associated mortality rate was 100% for zygomycosis, 80% for non-Aspergillus hyalohyphomycosis, 54% for aspergillosis, and 20% for phaeohyphomycosis. Thus, non-Aspergillus molds have emerged as significant pathogens in organ transplant recipients. These molds are more likely to be associated with disseminated infections and to be associated with poorer outcomes than is aspergillosis.

Antifungal activity of nonantifungal drugs

The antifungal activity of synthetic, nonchemotherapeutic compounds, antineoplastic agents and antibacterial drugs, such as sulphonamides, has been known since the early 20th century (1932). In this context, the term "nonantifungal" is taken to include a variety of compounds that are employed in the management of pathological conditions of nonfungal infectious etiology but have been shown to exhibit broad-spectrum antifungal activity. In this review, the antifungal properties of compounds such as chlorpromazine, proton pump inhibitors, antiarrhythmic agents, cholesterol-lowering agents, antineoplastic and immunosuppressive agents, antiparasitic drugs and antibiotics are described. Since fungi are eukaryotic cells, they share many pathways with human cells, thus increasing the probability of antifungal activity of "nonfungal drugs". The potential of these drugs for treatment of fungal infections has been investigated sporadically using the drugs alone or in combination with "classic" antifungal agents. A review of the literature, supplemented with a number of more recent investigations, suggests that some of these compounds enhance the activity of conventional antifungal agents, eliminate natural resistance to specific antifungal drugs (reversal of resistance) or exhibit strong activity against certain fungal strains in vitro and in animal models. The role of these agents in the epidemiology and in the clinical manifestations of fungal infections and the potential of certain drugs for treatment of invasive fungal infections require further investigation.

Efficacy of albaconazole (UR-9825) in treatment of disseminated Scedosporium prolificans infection in rabbits

There are no effective therapeutics for treating invasive Scedosporium prolificans infections. Doses of 15, 25, and 50 mg/kg of body weight/day for the new triazole albaconazole (ABC) were evaluated in an immunocompetent rabbit model of systemic infection with this mold. Treatments were begun 1 day after challenge and given for 10 days. ABC at any dose was more effective than amphotericin B (AMB) at 0.8 mg/kg/day at clearing S. prolificans from tissue (P < 0.007). The percentages of survival at 25 mg of ABC/kg/day were similar to those obtained with AMB. Rabbits showed 100% survival when they were treated with 50 mg of ABC per kg (P < 0.0001 versus control group), and only this dosage was able to reduce tissue burden significantly in the five organs studied, i.e., spleen, kidneys, liver, lungs, and brain.

Newer antifungal therapy for emerging fungal pathogens

As the number of immunocompromised patients increases, there is a concomitant increase in the number and diversity of fungal infections. Fungi that were once considered harmless or contaminants are now pathogenic in the immunocompromised host. Often these emerging pathogens are indistinguishable from the more familiar fungal infections; however, they are generally more recalcitrant to conventional antifungal therapies. With the antifungal armamentarium now expanding, the clinician now has many more options for these difficult-to-treat mycoses. We review many of the newer antifungal agents (second-generation triazoles, echinocandins, etc.) as therapeutic options for the recently emerging fungal pathogens.

In vitro drug interaction modeling of combinations of azoles with terbinafine against clinical Scedosporium prolificans isolates

The in vitro interaction between terbinafine and the azoles voriconazole, miconazole, and itraconazole against five clinical Scedosporium prolificans isolates after 48 and 72 h of incubation was tested by a microdilution checkerboard (eight-by-twelve) technique. The antifungal effects of the drugs alone and in combination on the fungal biomass as well as on the metabolic activity of fungi were measured using a spectrophotometric method and two colorimetric methods, based on the lowest drug concentrations showed 75 and 50% growth inhibition (MIC-1 and MIC-2, respectively). The nature and the intensity of the interactions were assessed using a nonparametric approach (fractional inhibitory concentration [FIC] index model) and a fully parametric response surface approach (Greco model) of the Loewe additivity (LA) no-interaction theory as well as a nonparametric (Prichard model) and a semiparametric response surface approaches of the Bliss independence (BI) no-interaction theory. Statistically significant synergy was found between each of the three azoles and terbinafine in all cases, although with different intensities. A 27- to 64-fold and 16- to 90-fold reduction of the geometric mean of the azole and terbinafine MICs, respectively, was observed when they were combined, resulting in FIC indices of <1 to 0.02. Using the MIC-1 higher levels of synergy were obtained, which were more consistent between the two incubation periods than using the MIC-2. The strongest synergy among the azoles was found with miconazole using the BI-based models and with voriconazole using the LA-based models. The synergistic effects both on fungal growth and metabolic activity were more potent after 72 h of incubation. Fully parametric approaches in combination with the modified colorimetric method might prove useful for testing the in vitro interaction of antifungal drugs against filamentous fungi.