The challenge of invasive fungal infection

Successful treatment of bilateral endogenous Fusarium solani endophthalmitis in a patient with acute lymphocytic leukaemia

Fusarium spp. are an uncommon cause of fungaemia in immunocompromised and neutropenic patients that may hematogenously disseminate to the eyes. Herein, we describe a patient with acute lymphoblastic leukaemia and a prior history of extensive corticosteroid exposure who developed disseminated Fusarium solani infection following chemotherapy despite posaconazole prophylaxis. She was successfully treated with combination liposomal amphotericin B and voriconazole, intraocular injections of voriconazole, topical amphotericin B and bilateral vitrectomy. We also review published literature describing the management of endogenous Fusarium endophthalmitis in immunocompromised hosts.

Synthesis and biological evaluation of new fluconazole β-lactam conjugates linked via 1,2,3-triazole

Novel fluconazole conjugates with potent antifungal activity are reported here. They were also found to be non-hemolytic and non-cytotoxic.

D-index: A New Scoring System in Febrile Neutropenic Patients for Predicting Invasive Fungal Infections

OBJECTIVE

Neutropenia is a critical risk factor for invasive fungal infections (IFIs). We retrospectively performed this study to assess the performance of the D-index, a new test that combines both the duration and the severity of neutropenia, in predicting IFIs among patients with acute myelogenous leukemia. 


MATERIALS AND METHODS

Fifteen patients with IFIs and 28 patients who did not develop IFIs were enrolled in the study. The D-index was defined as the area over the neutrophil curve, whereas the cumulative-D-index (c-D-index) was the area over the neutrophil curve from the start of neutropenia until the first clinical manifestation of IFI.


RESULTS

The D-index and the c-D-index tended to be significantly higher in patients with IFIs, with medians of 10,150 (range: 4000-22,000) and 5300 (range: 2300-22,200), respectively (p=0.037 and p=0.003, respectively). The receiver operating characteristic analyses showed that there was a cutoff point of 3875 for the D-index in predicting IFI; the sensitivity, specificity, and positive and negative predictive values were 100%, 67.9%, 35.4%, and 100%, respectively. There was also a cutoff point of 4225 for the c-D-index in predicting IFI; the sensitivity, specificity, and positive and negative predictive values for the c-D-index were 93.3%, 71.4%, 36.6%, and 98.4%. 


CONCLUSION

The D-index and especially the c-D-index could be useful tools with high negative predictive value to exclude as well as to predict IFIs in the management of neutropenic patients.

Sphingolipids as Regulators of the Phagocytic Response to Fungal Infections

Fungal infections pose a significant risk for the increasing population of individuals who are immunocompromised. Phagocytes play an important role in immune defense against fungal pathogens, but the interactions between host and fungi are still not well understood. Sphingolipids have been shown to play an important role in many cell functions, including the function of phagocytes. In this review, we discuss major findings that relate to the importance of sphingolipids in macrophage and neutrophil function and the role of macrophages and neutrophils in the most common types of fungal infections, as well as studies that have linked these three concepts to show the importance of sphingolipid signaling in immune response to fungal infections.

Identification of Scedosporium boydii catalase A1 gene, a reactive oxygen species detoxification factor highly expressed in response to oxidative stress and phagocytic cells

Scedosporium boydii is an opportunistic filamentous fungus which may be responsible for a large variety of infections in both immunocompetent and immunocompromised individuals. This fungus belongs to the Scedosporium apiospermum species complex which usually ranks second among the filamentous fungi colonizing the airways of patients with cystic fibrosis (CF). Species of the S. apiospermum complex are able to chronically colonize the CF airways suggesting pathogenic mechanisms allowing persistence and growth of these fungi in the respiratory tract. Few putative virulence factors have been purified and characterized so far in the S. apiospermum complex including a cytosolic Cu,Zn-superoxide dismutase (SOD) and a monofunctional catalase (catalase A1). Upon microbial infection, host phagocytes release reactive oxygen species (ROS), such as hydrogen peroxide, as part of the antimicrobial response. Catalases are known to protect pathogens against ROS by degradation of the hydrogen peroxide. Here, we identified the S. boydii catalase A1 gene (CATA1) and investigated its expression in response to the environmental conditions encountered in the CF airways and to the oxidative stress. Results showed that S. boydii CATA1 gene expression is not affected by hypoxia, hypercapnia or pH changes. In contrast, CATA1 gene was overexpressed in response to a chemically induced oxidative stress with a relative gene expression 37-fold higher in the presence of 250 μM H(2)O(2), 20-fold higher with 250 μM menadione and 5-fold higher with 2 mM paraquat. Moreover, S. boydii CATA1 gene expression progressively increased upon exposure to activated THP-1-derived macrophages, reaching a maximum after 12 h (26 fold). Activated HL60-derived neutrophils and activated human peripheral blood neutrophils more rapidly induced S. boydii CATA1 gene overexpression, a maximum gene expression level being reached at 75 min (17 fold) and 60 min (15 fold), respectively. In contrast expression of the gene encoding the Cu,Zn-SOD (SODC gene) was not affected by H(2)O(2), menadione, paraquat or in co-culture with phagocytic cells. These results suggest that S. boydii CATA1 gene is highly stimulated by the oxidative burst response whereas SODC gene is constitutively expressed.

Antifungal prophylaxis with posaconazole vs. fluconazole or itraconazole in pediatric patients with neutropenia

Pediatric patients with hemato-oncological malignancies and neutropenia resulting from chemotherapy have a high risk of acquiring invasive fungal infections. Oral antifungal prophylaxis with azoles, such as fluconazole or itraconazole, is preferentially used in pediatric patients after chemotherapy. During this retrospective analysis, posaconazole was administered based on favorable results from studies in adult patients with neutropenia and after allogeneic hematopoietic stem cell transplantation. Retrospectively, safety, feasibility, and initial data on the efficacy of posaconazole were compared to fluconazole and itraconazole in pediatric and adolescent patients during neutropenia. Ninety-three pediatric patients with hemato-oncological malignancies with a median age of 12 years (range 9 months to 17.7 years) that had prolonged neutropenia (>5 days) after chemotherapy or due to their underlying disease, and who received fluconazole, itraconazole, or posaconazole as antifungal prophylaxis, were analyzed in this retrospective single-center survey. The incidence of invasive fungal infections in pediatric patients was low under each of the azoles. One case of proven aspergillosis occurred in each group. In addition, there were a few cases of possible invasive fungal infection under fluconazole (n = 1) and itraconazole (n = 2). However, no such cases were observed under posaconazole. The rates of potentially clinical drug-related adverse events were higher in the fluconazole (n = 4) and itraconazole (n = 5) groups compared to patients receiving posaconazole (n = 3). Posaconazole, fluconazole, and itraconazole are comparably effective in preventing invasive fungal infections in pediatric patients. Defining dose recommendations in these patients requires larger studies.

Synthesis and biological evaluation of novel fluconazole analogues bearing 1,3,4-oxadiazole moiety as potent antifungal agents

A novel series of fluconazole based mimics incorporating 1,3,4-oxadiazole moiety were designed and synthesized. All the title compounds were characterized by (1)H-NMR, (13)C-NMR, and Q-TOF-MS. Preliminary results revealed that most of analogues exhibited significant antifungal activity against seven pathogenic fungi. Compounds 9g and 9k (MIC80 ≤ 0.125 μg/mL, respectively) were found more potent than the positive controls itraconazole and fluconazole as broad-spectrum antifungal agents. The observed docking results showed that the 1,3,4-oxadiazole moiety enhanced the affinity binding to the cytochrome P450 14α-demethylase (CYP51).

Murine model for Fusarium oxysporum invasive fusariosis reveals organ-specific structures for dissemination and long-term persistence

The soil-borne plant pathogen Fusarium oxysporum causes life-threatening invasive fusariosis in immunocompromised individuals. The mechanism of infection in mammalian hosts is largely unknown. In the present study we show that the symptoms of disseminated fusariosis caused by F. oxysporum in immunosuppressed mice are remarkably similar to those reported in humans. Distinct fungal structures were observed inside the host, depending on the infected organ. Invasive hyphae developed in the heart and kidney, causing massive colonization of the organs. By contrast, chlamydospore-like survival structures were found in lung, spleen and liver. Systemically infected mice also developed skin and eye infections, as well as thrombosis and necrosis in the tail. We further show that F. oxysporum can disseminate and persist in the organs of immunocompetent animals, and that these latent infections can lead to lethal systemic fusariosis if the host is later subjected to immunosuppressive treatment.

Proton translocating ATPase mediated fungicidal activity of eugenol and thymol

Eugenol (1) and thymol (2) exhibit excellent fungicidal activity against pathogenic yeasts, including isolates resistant to azoles. The rapid irreversible action of compound-1 and compound 2 on fungal cells suggested a membrane-located target for their action. We investigated their effect on H(+)-ATPase mediated H(+)-pumping by various Candida species. Both compounds inhibit H(+)-ATPase activity at their respective MIC values--500 and 100 μg/ml. Glucose stimulated H(+)-extrusion was also inhibited significantly by compound 1 and compound 2. Inhibition of H(+)-ATPase leads to intracellular acidification and cell death. Inhibition of cell growth and H(+)-efflux by test compounds suggests that their antifungal properties are related to their inhibitory effects on H(+)-ATPase.

Modes of action of the new arylguanidine abafungin beyond interference with ergosterol biosynthesis and in vitro activity against medically important fungi

BACKGROUND

In contrast to the increasing numbers of agents for the treatment of invasive fungal infections, discoveries of new antifungal agents with therapeutic value in dermatomycoses are reported only rarely.

METHODS

Abafungin (chemical abstracts service registry No. 129639-79/8) is the first member of a novel class of synthetic antifungal compounds, the arylguanidines. It was first synthesized at Bayer AG, Leverkusen, Germany, and its antifungal action was discovered during the screening of H(2)-receptor antagonists based on the structure of famotidine. To obtain insight into its mode of action and antifungal activity, various tests were carried out with different fungal pathogens in vitro.

RESULTS

Abafungin was found to have potent antifungal activity. Furthermore, mode-of-action studies suggested that abafungin exerts its antifungal activity regardless of whether the pathogens are growing or in a resting state. One target of abafungin was found to be the inhibition of transmethylation at the C-24 position of the sterol side chain, catalyzed by the enzyme sterol-C-24-methyltransferase. A second action of abafungin seems to be a direct effect on the fungal cell membrane.

CONCLUSION

The observed characteristics of abafungin indicate that abafungin might be a promising antifungal agent defining a new class of antimycotics.

A Case of Skull Base Mucormycosis with Osteomyelitis Secondary to Temporal Bone Squamous Cell Carcinoma

We describe an unusual case in which a 35-year-old man presented with skull base mucormycosis with osteomyelitis secondary to squamous cell carcinoma of the temporal bone. We also review the literature on the clinical characteristics, diagnosis, and treatment of mucormycosis.

Synergism of CAY-1 with Amphotericin B and Itraconazole

BACKGROUND

CAY-1 is a fungicidal saponin from cayenne pepper whose mode of action differs from amphotericin B (AB) and itraconazole (IT). This work determined CAY-1 synergism with AB or IT.

METHODS

CAY-1 was purified and used in checkerboard microdilution studies where CAY-1 and AB or IT were mixed with nongerminated (NG) and germinating (G) conidia of three Aspergillus species and Candida albicans. Inhibition was visually determined at 24 and 48 h.

RESULTS

CAY-1 had predominantly additive-synergistic interaction with AB or IT against the Aspergillus NG and G conidia. Excellent synergy between CAY-1 and AB occurred at 24 and 48 h against C. albicans. Results suggest CAY-1 enhances AB and IT efficacy.

Intensive care in patients with newly diagnosed malignancies and a need for cancer chemotherapy

OBJECTIVE

Patients with newly diagnosed cancer responsible for organ failures may require intensive care unit (ICU) admission and immediate chemotherapy. Outcomes in this population have not been studied.

DESIGN

Prospective observational cohort study.

SETTING

Teaching hospital.

SUBJECTS

All patients admitted to the ICU, from January 1997 to June 2003, for organ failures due to newly diagnosed, untreated cancer and deemed necessary to receive immediate cancer chemotherapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For the period of 6.5 yrs, 100 patients met the study criteria: 43 had acute leukemia, 37 lymphoma, and 12 solid tumors. Median Simplified Acute Physiology Score II was 39 (30-48) points, and median Logistic Organ Dysfunction score was 5 (3-7) points. Three variables were independently associated with 30-day mortality: need for vasopressor therapy (odds ratio, 6.01; 95% confidence interval, 1.86-19.4), mechanical ventilation (odds ratio, 6.36; 95% confidence interval, 1.76-22.94); and hepatic failure (odds ratio, 7.76; 95% confidence interval, 1.25-48.27). Overall survival was 60% after 30 days and 49% after 180 days.

CONCLUSIONS

Mortality was chiefly dependent on the nature and number of organ failures, not on the nature or stage of the malignancy. The 30-day and 180-day survival rates indicate that, in this selected group of patients, advanced disease at cancer diagnosis should not lead to refusal of ICU admission. Moreover, administration of chemotherapy in the intensive care unit is feasible, and although the mortality rate is high, routine ICU admission of patients with newly diagnosed cancer, specific organ failure, and the need for administration of chemotherapy in the ICU deserves evaluation.

The ATC1 Gene Encodes a Cell Wall-linked Acid Trehalase Required for Growth on Trehalose in Candida albicans

After screening a Candida albicans genome data base, the product of an open reading frame (IPF 19760/CA2574) with 41% identity to Saccharomyces cerevisiae vacuolar acid trehalase (Ath1p) was identified and named Atc1p. The deduced amino acid sequence shows that Atc1p contains an N-terminal hydrophobic signal peptide and 20 potential sites for N-glycosylation. C. albicans homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two ATC chromosomal alleles. Analysis of these null mutants shows that Atc1p is localized in the cell wall and is required for growth on trehalose as a carbon source. An Atc1p endowed with acid trehalase activity was obtained by an in vtro transcription-translation coupled system. These results strongly suggest that ATC1 is the structural gene encoding cell wall acid trehalase in C. albicans. Determinations of ATC1 mRNA expression as well as acid trehalase activity in the presence and absence of glucose point out that ATC1 gene is regulated by glucose repression.

Development and application of a rapid diagnostic method for invasive Candidiasis by the detection of d-/l-arabinitol using gas chromatography/mass spectrometry

A rapid non-culture-based diagnostic method utilizing d-/l-arabinitol (DA/LA) ratios as a chemical marker of invasive candidiasis was developed and explored. The enantiomers-ratios detection was made possible by the use of gas chromatography coupled with mass spectrometry (GC/MS). The mean DA/LA ratios +/- standard deviation (range) in urine (n = 40) and serum (n = 20) were 2.08 +/- 0.78 (0.57 to 3.55) and 1.79 +/- 0.75 (0.74 to 3.54), respectively, from patients without evidence of fungal infection or colonization; in patients (n = 7) with culture-proven invasive candida infections, the figures were 9.91 +/- 3.04 (7.24 to 16.27) and 13.58 +/- 7.31 (5.57 to 25.88) in urine and serum, respectively. The differences in DA/LA ratios between the candidemic patients and the non-candidemic patients were statistically significant (p < 0.01) in both serum and urine samples. The DA/LA ratios were not significantly affected in patients with oral or vaginal candidiasis and candiduria.

Disseminated mucormycosis in a patient with acute myeloblastic leukemia misdiagnosed as infection by Enterococcus faecium

Mucormycosis is a rare complication in cancer patients. This report presents the case of a acute myeloblastic leukemia patient who developed an ascending paralysis due to disseminated mucormycosis. The presentation was unusual because the early symptoms were fever and pain, and the disease was misdiagnosed because of a concomitant infection by Enterococcus faecium.

Cytokines in mice treated with amphotericin B-intralipid

Amphotericin B (AMB) intralipid (IL) admixtures (AMB-IL) are composed of components approved for clinical use and are commercially available at low cost. They are stable and exhibit in-vitro and in-vivo efficacy against Candida infections, as well as resulting in significantly reduced toxicity in comparison with that of conventionally administered amphotericin B. We examined the production of cytokines in uninfected mice treated with AMB or AMB-IL, as evaluated by expression of mRNA corresponding to the cytokines. Expression was measured by intensity of bands in comparison to the intensity of beta-actin control bands, with the latter assigned an arbitrary standard value of 100% and other bands measured in relative percentages. We found that both in naive and compromised mice, AMB treatment caused significantly greater production of the pro-inflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and interleukin 1 beta (IL-1beta) than was seen in animals treated with AMB-IL or with another lipid AMB formulation, AmBisome. We hypothesize that the superior tolerance for the AMB-IL admixtures, as compared with conventional AMB, might derive from the reduced expression of the pro-inflammatory cytokines. TNF-alpha and IL-1beta, which mediate many potentially adverse pathophysiological events similar to those seen as side-effects of AMB usage.

Role of antioxidant enzymatic defences against oxidative stress (H2O2) and the acquisition of oxidative tolerance inCandida albicans

In Candida albicans, trehalose plays an essential role as a protector of cell integrity against oxidative challenge. A double homozygous mutant, tps1/tps1, deficient in trehalose synthesis, displayed severe cell mortality when exposed to high H(2)O(2) concentrations, compared with its congenic parental (CAI-4) strain (Alvarez-Peral et al., 2002). We have examined the putative role of a set of well-known antioxidant enzymes as components of the defence mechanism against oxidative challenges. When exposed to mild non-lethal oxidative treatment (0.5 mM H(2)O(2)), a significant induction of catalase, glutathione reductase (GR), and Cu,Zn-superoxide dismutase (SOD) was recorded in tps1/tps1 exponential cultures. However, in CAI-4 cells, subjected to the same conditions, there was only a clear activation of catalase, Mn-SOD and Cu,Zn-SOD activities. The degree of activation was always much more pronounced in the trehalose-deficient mutant than in its wild-type counterpart, except for Mn-SOD activity. After exposure to severe oxidative stress (50 mM H(2)O(2)) only GR and catalase activities increased in tps1/tps1 cultures, whereas in CAI-4 cells GR but not catalase was induced. In both cell strains, 50 mM H(2)O(2) caused inhibition of the Mn- and Cu,Zn-SOD isozymes, this inhibition being more pronounced in tps1/tps1 cells. C. albicans is able to acquire adaptive oxidative tolerance by pretreatment with a low non-stressing concentration of H(2)O(2) before exposure to a drastic oxidative challenge. When these antioxidant activities were measured during the adaptive response, a greater degree of enzymatic antioxidant induction was consistently observed in the tps1/tps1 mutant with respect to the CAI-4 strain. Together with a higher intrinsic sensitivity of tps1/tps1 cells, we suggest that this unexpected increase might be explained in terms of a compensatory mechanism to overcome the lack of endogenous trehalose upon drastic oxidative exposure, although this induction was not sufficient to improve the percentage of cell viability.

Outcome predictors of 84 patients with hematologic malignancies and Fusarium infection

BACKGROUND

Invasive infection by Fusarium sp. is associated with high mortality in patients with hematologic cancer. Yet to the authors' knowledge, little is known regarding predictors of adverse outcome.

METHODS

The authors conducted a retrospective review of the records of patients with hematologic carcinoma and invasive fusariosis who were treated at one institution in the U.S. and at 11 centers in Brazil.

RESULTS

The records of 84 patients were evaluated. Neutropenia was present in 83% and 33 patients had undergone stem cell transplantation. Only 18 patients (21%) were alive 90 days after the diagnosis of fusariosis. Multivariate predictors of poor outcome were persistent neutropenia (hazard ratio [HR] of 5.43; 95% confidence interval [95% CI], 2.64-11.11) and use of corticosteroids (HR of 2.18; 95% CI, 1.98-3.96). The actuarial survival rate of patients without any of these factors was 67% compared with 30% for patients who recovered from neutropenia but were receiving corticosteroids and 4% for patients with persistent neutropenia only. None of the patients with both risk factors survived (P<0.0001).

CONCLUSIONS

Measures to reduce the duration of neutropenia, as well as the judicious use of corticosteroids, may reduce the high mortality rate of fusariosis in patients with hematologic cancer.

Amphotericin B/emulsion admixture interactions: an approach concerning the reduction of amphotericin B toxicity

Mixing Fungizone with a fat emulsion used for nutritional purpose (Intralipid or Lipofundin ) was reported to decrease Amphotericin B (AmB) toxicity in clinical use. In an effort to understand the reason for this phenomenon, spectral and morphological analyses were done for the Fungizone and Fungizone /Lipofundin admixture (FLmix). The absorption spectra analyses showed that not only Fungizone but also FLmix presented spectra that were concentration dependent. Moreover, the spectra of FLmix remained stable until the concentration of 5 x 10(-7) M, and only at 5 x 10(-8) M did they become similar in shape to the Fungizone spectra. Morphological studies revealed that even though emulsion droplets with or without Fungizone presented the same particle size, the former was less electron dense compared with Lipofundin alone. These results suggest a kind of association between Fungizoneand Lipofundin that remains over the whole range of concentrations. This hypothesis was confirmed by in vitro studies in which FLmix presented an important selectivity against human and fungal cells compared with Fungizone. These findings suggest that parenteral emulsions should be able to reduce the AmB toxicity probably by changing the AmB self-association state by binding it with emulsion droplets.

Cutaneous infection by Fusarium species in healthy and immunocompromised hosts: implications for diagnosis and management

Infections by Fusarium species frequently involve the skin, either as the primary or the metastatic site. To better understand the pathophysiology of these infections, 43 new patients with fusariosis were evaluated, and the literature was reviewed. A total of 259 patients (232 immunocompromised and 27 immunocompetent) were identified. Skin involvement was present in 70% of patients, particularly in immunocompromised patients (72% vs. 52%; P=.03). In immunocompetent patients, cutaneous infections were characterized by preceding skin breakdown, localized involvement, slow pace of progression, and good response to therapy. In contrast, skin involvement in immunocompromised patients was only occasionally preceded by skin breakdown and typically was presented as rapidly progressive disseminated lesions at various stages of evolution. Metastatic skin lesions were associated with fungemia, neutropenia, and death. Skin was the single source of diagnosis for the majority of immunocompromised and immunocompetent patients. Recommendations for the prevention of fatal fusariosis originating from skin are presented.

Disruption in Candida albicans of the TPS2 gene encoding trehalose-6-phosphate phosphatase affects cell integrity and decreases infectivity

The gene CaTPS2 encoding trehalose-6-phosphate (T6P) phosphatase from Candida albicans has been cloned and disrupted in this organism. The Catps2/Catps2 mutant did not accumulate trehalose but accumulated high levels of T6P. Disruption of the two copies of the CaTPS2 gene did not abolish growth even at 42 degrees C, but decreased the growth rate. In the stationary phase, the Catps2/Catps2 mutant aggregated, more than 50% of its cells became permeable to propidium iodide and a large amount of protein was found in the culture medium. Aggregation occurred only at pH values higher than 7 and was avoided by osmoprotectants; it was never observed during the exponential phase of growth. The mutant formed colonies with a smooth border on Spider medium. Mice inoculated with 1.5 x 10(6) c.f.u. of wild-type cells died after 8 days, while 80% of those inoculated with the same number of c.f.u. of the Catps2/Catps2 mutant survived for at least 1 month. Reintroduction of the wild-type CaTPS2 gene in the Catps2/Catps2 mutant abolished the phenotypes described. It is hypothesized that the accumulation of T6P interferes with the assembly of a normal cell wall.

Case report. Mycotic arteritis due to Aspergillus fumigatus in a diabetic with retrobulbar aspergillosis and mycotic meningitis

A 74-year-old man with diabetes mellitus type II, retinopathy and polyneuropathy suffered from exophthalmus, ptosis and diplopia. Magnetic resonance imaging and computer tomography showed a space-occupying process in the right orbital apex. An extranasal ethmoidectomy accompanied by an orbitotomia revealed the presence of septated hyphae. Aspergillus fumigatus was grown from the tissue. After surgical removal of the fungal masses, therapy with amphotericin B (1 mg kg(-1) body weight) plus itraconazole (Sempera, 200 mg per day) over 6 weeks was initiated. Five months later the patient's condition deteriorated again, with vomiting, nausea and pain behind the right eye plus increasing exophthalmus. Antifungal therapy was started again with amphotericin B and 5-fluorocytosine. Neutropenia did not occur. The patient became somnolent and deteriorated, a meningitis was suggested. Aspergillus antigen (titre 1:2, Pastorex) was detected in liquor. Anti-Aspergillus antibodies were not detectable. Both the right eye and retrobulbar fungal masses were eradicated by means of an exenteratio bulbi et orbitae. However, renal insufficiency and an apallic syndrome developed and the patient died. At autopsy, a mycotic aneurysm of the arteria carotis interna dextra was detected. The mycotic vasculitis of this aneurysm had caused a rupture of the blood vessel followed by a massive subarachnoidal haemorrhage. In addition, severe mycotic sphenoidal sinusitis and aspergillosis of the right orbit were seen, which had led to a bifrontal meningitis.

X-Ray crystal structures of Candida albicans dihydrofolate reductase: high resolution ternary complexes in which the dihydronicotinamide moiety of NADPH is displaced by an inhibitor

X-ray crystallographic analysis of 5-(4'-substituted phenyl)sulfanyl-2,4-diaminoquinazoline inhibitors in ternary complex with Candida albicans dihydrofolate reductase (DHFR) and NADPH revealed two distinct modes of binding. The two compounds with small 4'-substituents (H and CH3) were found to bind with the phenyl group oriented in the plane of the quinazoline ring system and positioned adjacent to the C-helix. In contrast, the more selective inhibitors with larger 4'-substituents (tert-butyl and N-morpholino) were bound to the enzyme with the phenyl group perpendicular to the quinazoline ring and positioned in the region of the active site that typically binds the dihydronicotinamide moiety of NADPH. The cofactor appeared bound to DHFR but with the disordered dihydronicotinamide swung away from the protein surface and into solution. This unusual inhibitor binding mode may play an important role in the high DHFR selectivity of these compounds and also may provide new ideas for inhibitor design.

Case report. Mixed systemic mycosis with fatal outcome in a patient with acute myeloblastic leukaemia

Fungal infections represent an increasing problem in immunocompromised patients. The majority of cases are caused by one single fungal pathogen and infections with more than one fungus are very rare. Here we describe a case of combined infection with Aspergillus and a zygomycete species, involving the lungs, spleen and the brain and leading to fatal outcome in spite of early antimycotic therapy.