Novel perspectives on mucormycosis: pathophysiology, presentation, and management

Mucormycosis is a life-threatening fungal infection that occurs in immunocompromised patients. These infections are becoming increasingly common, yet survival remains very poor. A greater understanding of the pathogenesis of the disease may lead to future therapies. For example, it is now clear that iron metabolism plays a central role in regulating mucormycosis infections and that deferoxamine predisposes patients to mucormycosis by inappropriately supplying the fungus with iron. These findings raise the possibility that iron chelator therapy may be useful to treat the infection as long as the chelator does not inappropriately supply the fungus with iron. Recent data support the concept that high-dose liposomal amphotericin is the preferred monotherapy for mucormycosis. However, several novel therapeutic strategies are available. These options include combination therapy using lipid-based amphotericin with an echinocandin or with an azole (largely itraconazole or posaconazole) or with all three. The underlying principles of therapy for this disease remain rapid diagnosis, reversal of underlying predisposition, and urgent surgical debridement.

Zygomycosis in the 1990s in a tertiary-care cancer center

Twenty-four patients with cancer met predetermined criteria for a diagnosis of zygomycosis over a 10-year period at our institution. All had hematologic malignancy, and most had either neutropenia or steroid use as a risk factor. Pulmonary involvement mimicking invasive aspergillosis was the most common presentation, and dissemination was seen in 58% of patients on whom autopsies were performed. Three-fourths of the patients with pulmonary zygomycosis had pathogenic microorganisms other than zygomycetes isolated from respiratory specimens. The sensitivity of cultures in detecting zygomycetes from respiratory specimens was low. A culture positive for zygomycetes was typically a preterminal finding in the fatal, acute cases. Two-thirds of the patients died. Favorable outcome seemed to correlate with lack of pulmonary involvement, surgical debridement, neutrophil recovery, and a cumulative total amphotericin B dose of 2000 mg. Therapy with high-dose amphotericin B, combined with aggressive surgery and immune reconstitution, offers the best chance for survival of cancer patients with zygomycosis.

Necrotizing cutaneous mucormycosis after a tornado in Joplin, Missouri, in 2011

BACKGROUND

Mucormycosis is a fungal infection caused by environmentally acquired molds. We investigated a cluster of cases of cutaneous mucormycosis among persons injured during the May 22, 2011, tornado in Joplin, Missouri.

METHODS

We defined a case as a soft-tissue infection in a person injured during the tornado, with evidence of a mucormycete on culture or immunohistochemical testing plus DNA sequencing. We conducted a case-control study by reviewing medical records and conducting interviews with case patients and hospitalized controls. DNA sequencing and whole-genome sequencing were performed on clinical specimens to identify species and assess strain-level differences, respectively.

RESULTS

A total of 13 case patients were identified, 5 of whom (38%) died. The patients had a median of 5 wounds (range, 1 to 7); 11 patients (85%) had at least one fracture, 9 (69%) had blunt trauma, and 5 (38%) had penetrating trauma. All case patients had been located in the zone that sustained the most severe damage during the tornado. On multivariate analysis, infection was associated with penetrating trauma (adjusted odds ratio for case patients vs. controls, 8.8; 95% confidence interval [CI], 1.1 to 69.2) and an increased number of wounds (adjusted odds ratio, 2.0 for each additional wound; 95% CI, 1.2 to 3.2). Sequencing of the D1-D2 region of the 28S ribosomal DNA yielded Apophysomyces trapeziformis in all 13 case patients. Whole-genome sequencing showed that the apophysomyces isolates were four separate strains.

CONCLUSIONS

We report a cluster of cases of cutaneous mucormycosis among Joplin tornado survivors that were associated with substantial morbidity and mortality. Increased awareness of fungi as a cause of necrotizing soft-tissue infections after a natural disaster is warranted.

A prospective multicenter study on mucormycosis in India: Epidemiology, diagnosis, and treatment

Mucormycosis due to Mucorales is reported at large numbers in uncontrolled diabetics across India, but systematic multicenter epidemiological study has not been published yet. The present prospective study was conducted at four major tertiary care centers of India (two in north and two in south India) during 2013-2015 to compare the epidemiology, treatment strategies and outcome of mucormycosis between the two regions. Molecular techniques were employed to confirm the identity of the isolates or to identify the agent in biopsy samples. A total of 388 proven/probable mucormycosis cases were reported during the study period with overall mortality at 46.7%. Uncontrolled diabetes (n = 172, 56.8%) and trauma (n = 31, 10.2%) were the common risk factors. Overall, Rhizopus arrhizus (n = 124, 51.9%) was the predominant agent identified, followed by Rhizopus microsporus (n = 30, 12.6%), Apophysomyces variabilis (n = 22, 9.2%) and Rhizopus homothallicus (n = 6, 2.5%). On multivariate analysis, the mortality was significantly associated with gastrointestinal (OR: 18.70, P = .005) and pulmonary infections (OR: 3.03, P = .015). While comparing the two regions, majority (82.7%) cases were recorded from north India; uncontrolled diabetes (n = 157, P = .0001) and post-tubercular mucormycosis (n = 21, P = .006) were significantly associated with north Indian cases. No significant difference was noted among the species of Mucorales identified and treatment strategies between the two regions. The mortality rate was significantly higher in north Indian patients (50.5%) compared to 32.1% in south India (P = .016). The study highlights higher number of mucormycosis cases in uncontrolled diabetics of north India and emergence of R. microsporus and R. homothallicus across India causing the disease.

PCR based identification and discrimination of agents of mucormycosis and aspergillosis in paraffin wax embedded tissue

BACKGROUND

Invasive fungal infections are often diagnosed by histopathology without identification of the causative fungi, which show significantly different antifungal susceptibilities.

AIMS

To establish and evaluate a system of two seminested polymerase chain reaction (PCR) assays to identify and discriminate between agents of aspergillosis and mucormycosis in paraffin wax embedded tissue samples.

METHODS

DNA of 52 blinded samples from five different centres was extracted and used as a template in two PCR assays targeting the mitochondrial aspergillosis DNA and the 18S ribosomal DNA of zygomycetes.

RESULTS

Specific fungal DNA was identified in 27 of 44 samples in accordance with a histopathological diagnosis of zygomycosis or aspergillosis, respectively. Aspergillus fumigatus DNA was amplified from one specimen of zygomycosis (diagnosed by histopathology). In four of 16 PCR negative samples no human DNA was amplified, possibly as a result of the destruction of DNA before paraffin wax embedding. In addition, eight samples from clinically suspected fungal infections (without histopathological proof) were examined. The two PCR assays detected a concomitant infection with Absidia corymbifera and A fumigatus in one, and infections with Rhizopus arrhizus and A fumigatus in another two cases.

CONCLUSIONS

The two seminested PCR assays described here can support a histopathological diagnosis of mucormycosis or aspergillosis, and can identify the infective agent, thereby optimising antifungal treatment.

Fungi that Infect Humans

Fungi must meet four criteria to infect humans: growth at human body temperatures, circumvention or penetration of surface barriers, lysis and absorption of tissue, and resistance to immune defenses, including elevated body temperatures. Morphogenesis between small round, detachable cells and long, connected cells is the mechanism by which fungi solve problems of locomotion around or through host barriers. Secretion of lytic enzymes, and uptake systems for the released nutrients, are necessary if a fungus is to nutritionally utilize human tissue. Last, the potent human immune system evolved in the interaction with potential fungal pathogens, so few fungi meet all four conditions for a healthy human host. Paradoxically, the advances of modern medicine have made millions of people newly susceptible to fungal infections by disrupting immune defenses. This article explores how different members of four fungal phyla use different strategies to fulfill the four criteria to infect humans: the Entomophthorales, the Mucorales, the Ascomycota, and the Basidiomycota. Unique traits confer human pathogenic potential on various important members of these phyla: pathogenic Onygenales comprising thermal dimorphs such as Histoplasma and Coccidioides; the Cryptococcus spp. that infect immunocompromised as well as healthy humans; and important pathogens of immunocompromised patients-Candida, Pneumocystis, and Aspergillus spp. Also discussed are agents of neglected tropical diseases important in global health such as mycetoma and paracoccidiomycosis and common pathogens rarely implicated in serious illness such as dermatophytes. Commensalism is considered, as well as parasitism, in shaping genomes and physiological systems of hosts and fungi during evolution.

Molecular identification of zygomycetes from culture and experimentally infected tissues

Mucormycosis is an emerging infection associated with a high mortality rate. Identification of the causative agents remains difficult and time-consuming by standard mycological procedures. In this study, internal transcribed spacer (ITS) sequencing was validated as a reliable technique for identification of Zygomycetes to the species level. Furthermore, species identification directly from infected tissues was evaluated in experimentally infected mice. Fifty-four Zygomycetes strains belonging to 16 species, including the most common pathogenic species of Rhizopus spp., Absidia spp., Mucor spp., and Rhizomucor spp., were used to assess intra- and interspecies variability. Ribosomal DNA including the complete ITS1-5.8S-ITS2 region was amplified with fungal universal primers, sequenced, and compared. Overall, for a given species, sequence similarities between isolates were >98%. In contrast, ITS sequences were very different between species, allowing an accurate identification of Zygomycetes to the species level in most cases. Six species (Rhizopus oryzae, Rhizopus microsporus, Rhizomucor pusillus, Mucor circinelloides, and Mucor indicus) were also used to induce disseminated mucormycosis in mice and to demonstrate that DNA extraction, amplification of fungal DNA, sequencing, and molecular identification were possible directly from frozen tissues.

Geosiphon pyriforme, a fungus forming endocytobiosis with Nostoc (cyanobacteria), is an ancestral member of the Glomales: evidence by SSU rRNA analysis

Geosiphon pyriforme inhabiting the surface of humid soils represents the only known example of endocytobiosis between a fungus (Zygomycotina; macrosymbiont) and cyanobacteria (Nostoc; endosymbiont). In order to elucidate the taxonomical and evolutionary relationship of Geosiphon pyriforme to fungi forming arbuscular mycorrhiza (AM fungi), the small-subunit (SSU) ribosomal RNA genes of Geosiphon pyriforme and Glomus versiforme (Glomales; a typical AM fungus) were analyzed and aligned with SSU rRNA sequences of several Basidiomycetes, Ascomycetes, Chytridiomycetes, and Zygomycetes, together with all AM-fungal (Glomales) sequences published yet. The distinct group of the order Glomales, which includes Geosiphon, does not form a clade with any other group of Zygomycetes. Within the Glomales, two main lineages exist. One includes the families Gigasporaceae and Acaulosporaceae; the other one is represented by the genus Glomus, the members of which are very divergent. Glomus etunicatum and Geosiphon pyriforme both form independent lineages ancestral to the Glomales. The data provided by the present paper confirm clearly that Geosiphon represents a fungus belonging to the Glomales. The question remains still open as to whether or not Geosiphon is to be placed within or outside the genus Glomus, since this genus is probably polyphyletic and not well defined yet. Geosiphon shows the ability of a Glomus-like fungus to form a "primitive" symbiosis with a unicellular photoautotrophic organism, in this case a cyanobacterium, leading to the conclusion that a hypothetical association of a Glomus-like fungus with a green alga as a step during the evolution of the land plants appears probable.

Phylogeny and origin of 82 zygomycetes from all 54 genera of the Mucorales and Mortierellales based on combined analysis of actin and translation elongation factor EF-1alpha genes

True fungi (Eumycota) are heterotrophic eukaryotic microorganisms encompassing ascomycetes, basidiomycetes, chytridiomycetes and zygomycetes. The natural systematics of the latter group, Zygomycota, are very poorly understood due to the lack of distinguishing morphological characters. We have determined sequences for the nuclear-encoded genes actin (act) from 82 zygomycetes representing all 54 currently recognized genera from the two zygomycetous orders Mucorales and Mortierellales. We also determined sequences for translation elongation factor EF-1alpha (tef) from 16 zygomycetes (total of 96,837 bp). Phylogenetic analysis in the context of available sequence data (total 2,062 nucleotide positions per species) revealed that current classification schemes for the mucoralean fungi are highly unnatural at the family and, to a large extent, at the genus level. The data clearly indicate a deep, ancient and distinct dichotomy of the orders Mucorales and Mortierellales, which are recognized only in some zygomycete systems. Yet at the same time the data show that two genera - Umbelopsis and Micromucor - previously placed within the Mortierellales on the basis of their weakly developed columella (a morphological structure of the sporangiophore well-developed within all Mucorales) are in fact members of the Mucorales. Phylogenetic analyses of the encoded amino acid sequences in the context of homologues from eukaryotes and archaebacterial outgroups indicate that the Eumycota studied here are a natural group but provide little or no support for the monophyly of either zygomycetes, ascomycetes or basidiomycetes. The data clearly indicate that a complete revision of zygomycete natural systematics is necessary.

Apophysomyces elegans: an emerging zygomycete in India

Apophysomyces elegans was considered a rare but medically important zygomycete. We analyzed the clinical records of eight patients from a single center in whom zygomycosis due to A. elegans was diagnosed over a span of 25 months. We also attempted a DNA-based method for rapid identification of the fungi and looked for interstrain polymorphism using microsattelite primers. Three patients had cutaneous and subcutaneous infections, three had isolated renal involvement, one had rhino-orbital tissue infection, and the final patient had a disseminated infection involving the spleen and kidney. Underlying illnesses were found in two patients, one with diabetes mellitus and the other with chronic alcoholism. A history of traumatic implantation was available for three patients. All except two of the patients responded to surgical and/or medical therapy; the diagnosis for the two exceptions was made at the terminal stage of infection. Restriction enzyme (MboI, MspI, HinfI) digestion of the PCR-amplified internal transcribed spacer region helped with the rapid and specific identification of A. elegans. The strains could be divided into two groups according to their patterns, with clustering into one pattern obtained by using microsatellite [(GTG)(5) and (GAC)(5)] PCR fingerprinting. The study highlights the epidemiology, clinical spectrum, and diagnosis of emerging A. elegans infections.

Genetic identification of the main opportunistic Mucorales by PCR-restriction fragment length polymorphism

Mucormycosis is a rare and opportunistic infection caused by fungi belonging to the order Mucorales. Recent reports have demonstrated an increasing incidence of mucormycosis, which is frequently lethal, especially in patients suffering from severe underlying conditions such as immunodeficiency. In addition, even though conventional mycology and histopathology assays allow for the identification of Mucorales, they often fail in offering a species-specific diagnosis. Due to the lack of other laboratory tests, a precise identification of these molds is thus notoriously difficult. In this study we aimed to develop a molecular biology tool to identify the main Mucorales involved in human pathology. A PCR strategy selectively amplifies genomic DNA from molds belonging to the genera Absidia, Mucor, Rhizopus, and Rhizomucor, excluding human DNA and DNA from other filamentous fungi and yeasts. A subsequent digestion step identified the Mucorales at genus and species level. This technique was validated using both fungal cultures and retrospective analyses of clinical samples. By enabling a rapid and precise identification of Mucorales strains in infected patients, this PCR-restriction fragment length polymorphism-based method should help clinicians to decide on the appropriate treatment, consequently decreasing the mortality of mucormycosis.

Whole genome sequence typing to investigate the Apophysomyces outbreak following a tornado in Joplin, Missouri, 2011

Case reports of Apophysomyces spp. in immunocompetent hosts have been a result of traumatic deep implantation of Apophysomyces spp. spore-contaminated soil or debris. On May 22, 2011 a tornado occurred in Joplin, MO, leaving 13 tornado victims with Apophysomyces trapeziformis infections as a result of lacerations from airborne material. We used whole genome sequence typing (WGST) for high-resolution phylogenetic SNP analysis of 17 outbreak Apophysomyces isolates and five additional temporally and spatially diverse Apophysomyces control isolates (three A. trapeziformis and two A. variabilis isolates). Whole genome SNP phylogenetic analysis revealed three clusters of genotypically related or identical A. trapeziformis isolates and multiple distinct isolates among the Joplin group; this indicated multiple genotypes from a single or multiple sources. Though no linkage between genotype and location of exposure was observed, WGST analysis determined that the Joplin isolates were more closely related to each other than to the control isolates, suggesting local population structure. Additionally, species delineation based on WGST demonstrated the need to reassess currently accepted taxonomic classifications of phylogenetic species within the genus Apophysomyces.

Purification and kinetics of a raw starch-hydrolyzing, thermostable, and neutral glucoamylase of the thermophilic mold Thermomucor indicae-seudaticae

The purified glucoamylase of the thermophilic mold Thermomucor indicae-seudaticaehad a molecular mass of 42 kDa with a pI of 8.2. It is a glycoprotein with 9-10.5% carbohydrate content, which acted optimally at 60 degrees C and pH 7.0, with a t(1/2) of 12 h at 60 degrees C and 7 h at 80 degrees C. Its experimental activation energy was 43 KJ mol(-1) with temperature quotient (Q(10)) of 1.35, while the values predicted by response surface methodology (RSM) were 43 KJ mol(-1) and 1.28, respectively. The enzyme hydrolyzed soluble starch at 50 degrees C (K(m) 0.50 mg mL(-1) and V(max) 109 micromol mg(-1) protein min(-1)) and at 60 degrees C (K(m) 0.40 and V(max) 143 micromol mg(-1) protein min(-1)). The experimental K(m) and V(max) values are in agreement with the predicted values at 50 degrees C (K(m) 0.45 mg mL(-1) and V(max) 111.11 micromol mg(-1) protein min(-1)) and at 60 degrees C (K(m) 0.36 mg mL(-1)and V(max) 142.85 micromol mg(-1) protein min(-1)). An Arrhenius plot indicated thermal activation up to 60 degrees C, and thereafter, inactivation. The enzyme was strongly stimulated by Co(2+), Fe(2+), Ag(2+), and Ca(2+), slightly stimulated by Cu(2+) and Mg(2+), and inhibited by Hg(2+), Zn(2+), Ni(2+), and Mn(2+). Among additives, dextran and trehalose slightly enhanced the activity. Glucoamylase activity was inhibited by EDTA, beta-mercaptoethanol, dithiothreitol, and n-bromosuccinimide, and n-ethylmaleimide inhibited its activity completely. This suggested the involvement of tryptophan and cysteine in catalytic activity and the critical role of disulfide linkages in maintaining the conformation of the enzyme. The enzyme hydrolyzed around 82% of soluble starch and 65% of raw starch (K(m) 2.4 mg mL(-1), V(max) 50 micromol mg(-1) protein min(-1)), and it was remarkably insensitive to glucose, suggesting its applicability in starch saccharification.

Rapid susceptibility testing of medically important zygomycetes by XTT assay

The XTT colorimetric assay quantifies fungal growth by measuring fungal metabolism and has been used successfully for susceptibility testing of Aspergillus species after 24 and 48 h of incubation. In the present study using 14 clinical isolates of Zygomycetes (Rhizopus oryzae [5 isolates], Cunninghamella spp. [3 isolates], Mucor spp. [3 isolates], and Absidia corymbifera [3 isolates]), significant metabolic activity was demonstrated before visual or spectrophotometric detection of fungal growth by performing the XTT assay as early as 6 h after inoculation. Testing of susceptibility to amphotericin B, posaconazole, and voriconazole was subsequently performed using the XTT method (100 microg/ml XTT, 25 microM menadione) at 6, 8, or 12 h after inoculation and the CLSI (formerly NCCLS) M38-A method with visual and spectrophotometric MIC determinations at 24 h after inoculation. Concentration-effect curves obtained with the use of the E(max) model (a sigmoid curve with variable slope) were comparable between the early XTT and spectrophotometric readings at 24 h. Complete inhibition of early metabolic activity with the azoles was delayed in comparison to that with amphotericin B. Using appropriate cutoff levels, agreement was demonstrated between the early XTT and 24-h spectrophotometric or visual readings. In particular, for MIC-0 (the lowest drug concentration showing absence of visual growth) of amphotericin B, overall agreement levels were 90 to 93% for the 6-h XTT assay and 100% for the 8- and 12-h time points. For MIC-0 of posaconazole, agreement levels were 86% for the 6-h XTT and 93 to 100% for the 8- and 12-h time points. The overall agreement levels for MIC-0 and MIC-2 (the lowest drug concentration showing prominent reduction of growth compared with the control well) of voriconazole (compared with 24-h spectrophotometric readings) were 93 to 98% for the 8- and 12-h XTT assays. These results support the use of the XTT method for rapid MIC determination for Zygomycetes.

Delimitation of Umbelopsis (Mucorales, Umbelopsidaceae fam. nov.) based on ITS sequence and RFLP data

In a continuation of studies started by de Ruiter et al. (1993), all known species of the Mortierella isabellina-group (Micromucor/Umbelopsis clade of O'Donnell et al. 2001) and a few other Mucorales and species of Mortierella were investigated by RFLP (including ITS1, 5.8S, ITS2 and the 5' end of the large subunit rDNA gene) and ITS1 sequence analyses. This monophyletic group is unrelated to Mortierella and is only distantly related to the core group of the Mucoraceae. M. longicollis falls outside the Umbelopsis clade. Molecular data resolved two subclades within the M. isabellina-group; however, they are not correlated with any differences in sporangial wall and shape, spore pigmentation and shape, or sporangiophore branching. Therefore we subsume all taxa in one genus, Umbelopsis. The new family Umbelopsidaceae and the new combinations U. isabellina, U. ramanniana, and U. autotrophica are proposed.

Phylogenetic diversity and antimicrobial activities of fungi associated with Haliclona simulans isolated from Irish coastal waters

The diversity and antimicrobial activities of 80 fungi isolated from Haliclona simulans were assessed using different fungal media containing either agar or gellum gum. In total, 19 different genotypes were detected. These fungal isolates could be classified as members of the Agaricomycotina, Mucoromycotina, Saccharomycotina, and Pezizomycotina, although the majority of the isolates were associated with the latter class. Some of these fungal isolates showed antimicrobial inhibition of Escherichia coli, Bacillus sp., Staphylococcus aureus, and Candida glabrata. Fungal 18S rRNA gene sequences belonging to Eurotiales, Calosphaeriales, and Chaetothyriales were amplified from DNA and RNA extracted from this marine sponge. This study indicates that in contrast to the low diversity of fungi detected by polymerase chain reaction (PCR) and reverse transcription (RT)-PCR amplification from extracts of this marine sponge, a much higher diversity of fungi could be cultured. The data suggests that some fungi live in symbiosis with H. simulans, whereas other fungi may have been ingested from the surrounding seawater.

Comparison of the EUCAST and CLSI Broth Microdilution Methods for Testing Isavuconazole, Posaconazole, and Amphotericin B against Molecularly Identified Mucorales Species

We compared EUCAST and CLSI antifungal susceptibility testing (AFST) methods for triazoles and amphotericin B against 124 clinical Mucorales isolates. The EUCAST method yielded MIC values 1- to 3-fold dilutions higher than those of the CLSI method for amphotericin B. The essential agreements between the two methods for triazoles were high, i.e., 99.1% (voriconazole), 98.3% (isavuconazole), and 87% (posaconazole), whereas it was significantly lower for amphotericin B (66.1%). Strategies for harmonization of the two methods for Mucorales AFST are warranted.

Cunninghamella: a newly recognized cause of rhinocerebral mucormycosis

Cunninghamella, a zygomycete in the order Mucorales, is an extremely rare cause of human infection. Of the five reported cases of human disease caused by this fungus, none involved rhinocerebral infection. Here, the authors document what appears to be the first case of rhinocerebral mucormycosis caused by Cunninghamella bertholletiae in an elderly man who had diabetes with sideroblastic anemia and hemochromatosis. The disease was rapidly fatal. The mycology and classification of this organism are presented, and the previous case reports in the literature are reviewed.

Nosocomial zygomycotic post-surgical necrotizing fasciitis in a healthy adult caused by Apophysomyces elegans in south India

Necrotizing fasciitis caused by the zygomycete Apophysomyces elegans of the anterior abdominal wall of a young healthy woman following a lower segment caesarean section is reported. Early clinical diagnosis and laboratory identification followed by appropriate management involving extensive tissue debridement and adequate doses of amphotericin B were eventually successful in controlling the infection and saving her life.

Species Identification and Delineation of Pathogenic Mucorales by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

This study aimed to validate the effectiveness of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based identification of filamentous fungi of the order Mucorales. A total of 111 isolates covering six genera preserved at the Research Center for Medical Mycology of Peking University were selected for MALDI-TOF MS analysis. We emphasized the study of 23 strains of Mucor irregularis predominantly isolated from patients in China. We first used the Bruker Filamentous Fungi library (v1.0) to identify all 111 isolates. To increase the identification rate, we created a compensatory in-house database, the Beijing Medical University (BMU) database, using 13 reference strains covering 6 species, including M. irregularis, Mucor hiemalis, Mucor racemosus, Cunninghamella bertholletiae, Cunninghamella phaeospora, and Cunninghamella echinulata All 111 isolates were then identified by MALDI-TOF MS using a combination of the Bruker library and BMU database. MALDI-TOF MS identified 55 (49.5%) and 74 (66.7%) isolates at the species and genus levels, respectively, using the Bruker Filamentous Fungi library v1.0 alone. A combination of the Bruker library and BMU database allowed MALDI-TOF MS to identify 90 (81.1%) and 111 (100%) isolates at the species and genus levels, respectively, with a significantly increased accuracy rate. MALDI-TOF MS poorly identified Mucorales when the Bruker library was used alone due to its lack of some fungal species. In contrast, this technique perfectly identified M. irregularis after main spectrum profiles (MSPs) of relevant reference strains were added to the Bruker library. With an expanded Bruker library, MALDI-TOF MS is an effective tool for the identification of pathogenic Mucorales.

Laboratory identification of Saksenaea vasiformis: a rare cause of zygomycosis in Australia

Saksenaea vasiformis was identified as the causative agent in three cases of sub-cutaneous zygomycosis in Australia. The laboratory techniques for inducing clinical isolates of S. vasiformis to produce sporangia, necessary for the precise identification of the fungus, are described and compared.

Primary cutaneous zygomycosis due to Mucor circinelloides

A 62-year-old woman with myelodysplastic syndrome presented with a 4-week history of a large indurated ulcer with a black eschar on the forearm following trauma. On biopsy a diagnosis of zygomycosis was made as broad, sparsely septate, thin-walled hyphae were seen in the deep dermis and subcutaneous fat. The zygomycete fungus Mucor circinelloides was cultured from tissue. Further investigation confirmed that the infection was localized to the skin. The 6 x 4 cm lesion was excised and the defect closed with a neurovascular island flap. No other treatment was undertaken. The patient died 6 months later from her haematological disease without recurrence of the fungal infection.

Comparative antigenic studies of species of Basidiobolus and other medically important fungi

An immunodiffusion technique was used to evaluate the antigenic relationship of various pathogenic and saprobic Basidiobolus spp., Conidiobolus spp., isolates of the order Mucorales, and several other medically important nonzygomycetous fungi. The antiserum to Basidiobolus haptosporus shared two lines of identity, designated inner (N) and outer (Y), when tested against exoantigens of known strains of B. haptosporus and Basidiobolus ranarum as well as exoantigens of a human Nigerian isolate and several wild isolates tentatively identified in B. ranarum. Both bands were heat stable at 56 degrees C for 30 min. Exoantigens of strains of Basidiobolus meristosporus, Basidiobolus microsporus, Conidiobolus incongruus, Conidiobolus coronatus, and other wild isolates of Basidiobolus spp. tested formed only the N immunoprecipitin band. Exoantigens of 10 isolates from other taxa did not produce any cross-reactive precipitin line. B. meristosporus antiserum that was tested against exoantigens of Basidiobolus spp. and of Conidiobolus spp. developed only an N band without a Y band. These data suggest that B. haptosporus and B. ranarum are antigenically similar to each other and distinct from B. meristosporus. Basidiobolus spp. and Conidiobolus spp. share a common N immunoprecipitin band, which implies a taxonomic relationship between these two genera. The absence of lines of identity between Basidiobolus spp. and other fungi tested suggests that, antigenically, Basidiobolus is a distinct genus.

Maxillary sinusitis caused by Actinomucor elegans

We report the first case of maxillary sinusitis caused by Actinomucor elegans in an 11-year-old patient. Histopathological and mycological examinations of surgical maxillary sinuses samples showed coenocytic hyphae characteristic of mucoraceous fungi. The fungi recovered had stolons and rhizoids, nonapophyseal and globose sporangia, and whorled branched sporangiophores and was identified as A. elegans. After surgical cleaning and chemotherapy with amphotericin B administered intravenously and by irrigation, the patient became asymptomatic and the mycological study results were negative.