Scedosporium apiospermum external otitis.

We report a case of Scedosporium apiospermum external otitis. The patient was topically treated with miconazole cream and achieved a clinical and mycological cure. The etiology, diagnosis and treatment of external fungal otitis are discussed.     

Hydroxamate siderophores of Scedosporium apiospermum

Scedosporium apiospermum is an emerging pathogen colonizing the airways of patients with cystic fibrosis and causing severe infections in immunocompromised hosts. In order to improve our knowledge on the pathogenic mechanisms of this fungus, we investigated the production of siderophores. Cultivation on CAS medium and specific assays for different classes of siderophores suggested the secretion of hydroxamates. A maximal production was obtained by cultivation of the fungus at alkaline pH in an iron-restricted liquid culture medium. Siderophores were then extracted from the culture filtrate by liquid/liquid extraction, and separated by reverse phase high performance liquid chromatography. Two siderophores, dimerumic acid and N ^α-methyl coprogen B, were identified by electrospray ionization-mass spectrometry and MS–MS fragmentation. Finally, comparison of various strains suggested a higher production of N ^α-methyl coprogen B by clinical isolates of respiratory origin. Studies are initiated in order to determine the potential usefulness of these siderophores as diagnostic markers of scedosporiosis.     

Scedosporium apiospermum Complex: Diagnosis and Species Identification

Fungi belonging to the Scedosporium apiospermum species complex have been known since the early 20th century as etiologic agents of human infections occurring in immunocompetent individuals as well as immunocompromised people. Additionally, these fungi are now recognized as common colonizers of the airways in patients with cystic fibrosis (CF). The prevalence and importance of these opportunistic pathogens have likely been underestimated, due to the absence of specific features on histological examination of biopsy specimens and the rapid and extensive growth of the aspergilli, which are frequently associated with Scedosporium species in respiratory secretions from CF patients or patients with chronic obstructive pulmonary disease. In this article, the literature on diagnostic and/or identification methods has been reviewed. Development of molecular tools brings about novel challenges in the field of diagnosis, and further studies are required to transfer these methods to routine clinical use.     

Scedosporium (Monosporium) apiospermum: multiple brain abscesses

A 32-year-old female with alcoholic cirrhosis attempted to drown herself in a pond. She remained in a coma for 57 days. After a stormy course she developed multiple brain abscesses due to Scedosporium (Monosporium) apiospermum. Despite intravenous and intrathecal amphotericin B (total dose 870 mg) the patient died 71 days after the near drowning.     

尖端赛多孢和多育赛多孢所致的深部真菌感染2例并文献复习

目的分别报道国内少见的由尖端赛多孢导致的化脓性关节感染伴骨髓炎和多育赛多孢的血行播散感染。方法取患者1的关节冲洗液和患者2的外周血标本直接涂片和真菌培养,根据真菌培养的菌落特点和镜下形态,鉴定致病菌种,并对分离的致病菌进行体外药敏试验。结果两个病例分别培养出尖端赛多孢和多育赛多孢。体外药敏试验显示两种菌对伏立康唑有较低的MIC值,而都对两性霉素B高耐。结论赛多孢菌的感染少见,且难治疗。应加深对少见真菌病的认识,提高诊治水平。     

Toluene biofiltration by the fungus Scedosporium apiospermum TB1

The performance of biofilters inoculated with the fungus Scedosporium apiospermum was evaluated. This fungus was isolated from a biofilter which operated with toluene for more than 6 months. The experiments were performed in a 2.9 L reactor packed with vermiculite or with vermiculite-granular activated carbon as packing material. The initial moisture content of the support and the inlet concentration of toluene were 70% and 6 g/m3, respectively. As the pressure drop increased from 5-40 mm H2O a strong initial growth was observed. Stable operation was maintained for 20 days with a moisture content of 55% and a biomass of 33 mg biomass/g dry support. These conditions were achieved with intermittent addition of culture medium, which permitted a stable elimination capacity (EC) of 100 g/m3(reactor)h without clogging. Pressure drop across the bed and CO2 production were related to toluene elimination. Measurement of toluene, at different levels of the biofilter, showed that the system attained higher local EC (200 g/m3(r)h) at the reactor outlet. These conditions were related to local humidity conditions. When the mineral medium was added periodically before the EC decreases, EC of approximately 258 g/m3(r)h were maintained with removal efficiencies of 98%. Under these conditions the average moisture content was 60% and 41 mg biomass/g dry support was produced. No sporulation was observed. Evaluation of bacterial content and activities showed that the toluene elimination was only due to S. apiospermum catabolism.     

尖端赛多孢子菌所致肺部感染1例

报道1例吸入性肺炎合并尖端赛多孢子菌感染,并对其临床表现、真菌分离培养及生物学特性进行研究和分析。     

Endobronchitis by Scedosporium apiospermum in a child with cystic fibrosis

A case of endobronchitis by Scedosporium apiospermum in a child with cystic fibrosis is presented. The bronchial aspirate's cytology showed the presence of a large amount of septated-dichotomized hyphae. The bronchial aspirate's culture showed the presence of Scedosporium apiospermum in a pure culture of three consecutive samples. The scanning electron microscopy study of the mucosal surface revealed scarce mycelia with the presence of abundant conidiae. The transmission electron microscopy of the mucosa revealed inflammatory infiltrates constituted by macrophages, polymorphonuclear leukocytes, a lot of dichotomized mycelia and macrophages with hyphae and conidiae within the phagosomes. The patient was treated with amphotericin B and itraconazole.     

Monoclonal antibodies against peptidorhamnomannans of Scedosporium apiospermum enhance the pathogenicity of the fungus

Scedosporium apiospermum is part of the Pseudallescheria-Scedosporium complex. Peptidorhamnomannans (PRMs) are cell wall glycopeptides present in some fungi, and their structures have been characterized in S. apiospermum, S. prolificans and Sporothrix schenckii. Prior work shows that PRMs can interact with host cells and that the glycopeptides are antigenic. In the present study, three monoclonal antibodies (mAbs, IgG1) to S. apiospermum derived PRM were generated and their effects on S. apiospermum were examined in vitro and in vivo. The mAbs recognized a carbohydrate epitope on PRM. In culture, addition of the PRM mAbs increased S. apiospermum conidia germination and reduced conidial phagocytosis by J774.16 macrophages. In a murine infection model, mice treated with antibodies to PRM died prior to control animals. Thus, PRM is involved in morphogenesis and the binding of this glycopeptide by mAbs enhanced the virulence of the fungus. Further insights into the effects of these glycopeptides on the pathobiology of S. apiospermum may lead to new avenues for preventing and treating scedosporiosis.     

尖端赛多孢子菌引起的真菌性鼻窦炎1例并文献复习

目的 探讨尖端赛多孢子菌的实验室检测方法,了解其对5种常用抗真菌药物的体外敏感性.通过对相关文献的复习,熟悉真菌性鼻窦炎的临床表现和诊治方法.方法 将1例尖端赛多孢子菌引起的真菌性鼻窦炎患者经鼻内腔镜手术切除的团块用10％ KOH压片镜检、涂片革兰染色镜检、沙堡弱培养基培养、分子生物学方法鉴定到种.分离株应用E-test进行体外药敏试验.结果 鉴定为尖端赛多孢子菌.5种药物对其MIC范围分别为:伏立康唑0.064 μg/mL,卡泊芬净1.500 μg/mL,氟康唑16.000 μg/mL,两性霉素B＞32.000 μg/mL,5-氟胞嘧啶＞32.000 μg/mL.结论 尖端赛多孢子菌引起的真菌性鼻窦炎国内少见报道,易与肿瘤相混淆;实验室检测对正确诊断起决定性作用;行鼻内腔镜下手术治疗效果较好.了解该菌的耐药性对指导抗真菌治疗尤为关键.     

Characterization of Scedosporium apiospermum Glucosylceramides and Their Involvement in Fungal Development and Macrophage Functions

Scedosporium apiospermum is an emerging fungal pathogen that causes both localized and disseminated infections in immunocompromised patients. Glucosylceramides (CMH, GlcCer) are the main neutral glycosphingolipids expressed in fungal cells. In this study, glucosylceramides (GlcCer) were extracted and purified in several chromatographic steps. Using high-performance thin layer chromatography (HPTLC) and electrospray ionization mass spectrometry (ESI-MS), N-2′-hydroxyhexadecanoyl-1-β-D-glucopyranosyl-9-methyl-4,8-sphingadienine was identified as the main GlcCer in S. apiospermum. A monoclonal antibody (Mab) against this molecule was used for indirect immunofluorescence experiments, which revealed that this CMH is present on the surface of the mycelial and conidial forms of S. apiospermum. Treatment of S. apiospermum conidia with the Mab significantly reduced fungal growth. In addition, the Mab also enhanced the phagocytosis and killing of S. apiospermum by murine cells. In vitro assays were performed to evaluate the CMHs for their cytotoxic activities against the mammalian cell lines L.929 and RAW, and an inhibitory effect on cell proliferation was observed. Synergistic invitro interactions were observed between the Mab against GlcCer and both amphotericin B (AmB) and itraconazole. Because Scedosporium species develop drug resistance, the number of available antifungal drugs is limited; our data indicate that combining immunotherapy with the available drugs might be a viable treatment option. These results suggest that in S. apiospermum, GlcCer are most likely cell wall components that are targeted by antifungal antibodies, which directly inhibit fungal development and enhance macrophage function; furthermore, these results suggest the combined use of monoclonal antibodies against GlcCer and antifungal drugs for antifungal immunotherapy.     

Molecular cloning and biochemical characterization of a Cu,Zn-superoxide dismutase from Scedosporium apiospermum

A Cu,Zn-superoxide dismutase has been characterized from Scedosporium apiospermum, a fungus which often colonizes the respiratory tract of patients with cystic fibrosis. Enzyme production was stimulated by iron starvation. Purification was achieved from mycelial extract from 7-day-old cultures on Amberlite XAD-16. The purified enzyme presented a relative molecular mass of 16.4 kDa under reducing conditions and was inhibited by potassium cyanide and diethyldithiocarbamate, which are two known inhibitors of Cu,Zn-SODs. Its optimum pH was 7.0 and the enzyme retained full activity after pretreatment at temperatures up to 50 degrees C. Moreover, a 450-bp fragment of the gene encoding the enzyme was amplified by PCR using degenerate primers designed from sequence alignment of four fungal Cu,Zn-SODs. Sequence data from this fragment allowed us to design primers which were used to amplify by walking-PCR the flanking regions of the known fragment. SaSODC gene (890 bp) corresponded to a 154 amino acid polypeptide with a predicted molecular mass of 15.9 kDa. A database search for sequence homology revealed for the deduced amino acid sequence 72 and 83% identity rate with Cu,Zn-SODs from Aspergillus fumigatus and Neurospora crassa, respectively. To our knowledge, this enzyme is the first putative virulence factor of S. apiospermum to be characterized.     

Assessment of biofilm formation by Scedosporium apiospermum,S. aurantiacum,S. minutisporum and Lomentospora prolificans

Reported herein is the ability of Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans conidia to adhere, differentiate into hyphae and form biofilms on both polystyrene and lung epithelial cells. To different degrees, all of the fungi adhered to polystyrene after 4 h, with a predominance of those with germinated conidia. Prolonged fungi–polystyrene contact resulted in the formation of a monolayer of intertwined mycelia, which was identified as a typical biofilm structure due to the presence of a viable mycelial biomass, extracellular matrix and enhanced antifungal resistance. Ultrastructural details were revealed by SEM and CLSM, showing the dense compaction of the mycelial biomass and the presence of channels within the organized biofilm. A similar biofilm structure was observed following the co-culture of each fungus with A549 cells, revealing a mycelial trap covering all of the lung epithelial monolayer. Collectively, these results highlight the potential for biofilm formation by these clinically relevant fungal pathogens.     

Pathogenesis of Scedosporium

Invasive scedosporiosis is a severe fungal infection, caused by species of the genus Scedosporium (Pseudallescheria teleomorph), usually refractory to treatment and with a common fatal outcome. Although the pathogenesis mechanisms involved in these infections are poorly known some progress has been made in recent years. This paper revises the available data on the experimental virulence and in the identification of virulence factors determinants, as well as the role of the host immune response in the control of the infection. In addition, the basic conditions needed for the invasion and dissemination of Scedosporium in the human body are described and discussed.