Trichosporon asahii infection presenting as chronic meningo‐ventriculitis and intra ventricular fungal ball: a case report and literature review

Central nervous system trichosporonosis is a rare clinical entity and so far only six cases including three each of brain abscess and meningitis has been on record. We report a rare case of chronic meningo‐ventriculitis and intraventricular fungal ball due to Trichosporon asahii in an 18‐year‐old immunocompetent male from Burundi, east Africa. Neuroendoscopy showed multiple nodules and a fungal ball within the ventricle, which on culture grew T. asahii. He was initially empirically treated with liposomal amphotericin B. However, the antifungal susceptibility testing of T. asahii isolate revealed high minimum inhibitory concentration for amphotericin B (2 μg ml^?1), flucytosine (16 μg ml^?1) and caspofungin (2 μg ml^?1) but exhibited potent activity for voriconazole, posaconazole, itraconazole and fluconazole. The patient rapidly succumbed to cardiac arrest before antifungal therapy could be changed. Although disseminated trichosporonosis has been increasingly reported the diagnosis represents a challenge especially in rare clinical settings such as intraventricular fungal ball in the present case, which has not been described previously.     

Susceptibility profile and epidemiological cut‐off values of Cryptococcus neoformans species complex from Argentina

Epidemiological cut‐off values (ECVs) based on minimal inhibitory concentration (MIC) distribution have been recently proposed for some antifungal drug/Cryptococcus neoformans combinations. However, these ECVs vary according to the species studied, being serotypes and the geographical origin of strains, variables to be considered. The aims were to define the wild‐type (WT) population of the C. neoformans species complex (C. neoformans) isolated from patients living in Argentina, and to propose ECVs for six antifungal drugs. A total of 707 unique C. neoformans isolates obtained from HIV patients suffering cryptococcal meningitis were studied. The MIC of amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole was determined according to the EDef 7.2 (EUCAST) reference document. The MIC distribution, MIC₅₀, MIC₉₀ and ECV for each of these drugs were calculated. The highest ECV, which included ≥95% of the WT population modelled, was observed for flucytosine and fluconazole (32 μg ml^?1 each). For amphotericin B, itraconazole, voriconazole and posaconazole, the ECVs were: 0.5, 0.5, 0.5 and 0.06 μg ml^?1 respectively. The ECVs determined in this study may aid in identifying the C. neoformans strains circulating in Argentina with decreased susceptibility to the antifungal drugs tested.     

In vitro activity of colistin as single agent and in combination with antifungals against filamentous fungi occurring in patients with cystic fibrosis

Because published reports indicate that the antibiotic colistin (COL) has antifungal properties, this study investigated the antifungal in vitro activity of COL as single agent and in combination with the antifungal compounds voriconazole (VRC), caspofungin (CAS) and amphotericin B (AMB) against Scedosporium/Pseudallescheria spp., Exophiala dermatitidis and Geosmithia argillacea. In total, susceptibility was determined for 77 Scedosporium/Pseudallescheria spp., 82 E. dermatitidis and 17 G. argillacea isolates. The minimal inhibitory concentrations (MICs) of COL and the antifungals as single compound and in combination were determined with MIC test strips. Drug interactions were detected by crossing the MIC test strips at a 90º angle. The fractional inhibitory concentration index was used to categorise the drugs’ interaction. The MIC₅₀ value of COL was 12 μg ml^?1 for S. prolificans, 16 μg ml^?1 for P. apiosperma, 16 μg ml^?1 for P. boydii, 12 μg ml^?1 for E. dermatiditis and 6 μg ml^?1 for G. argillacea. VRC was the most active drug in combination without any antagonism with the exception of few P. boydii isolates. COL as single agent and in most combinations with antifungals exhibits in vitro antifungal activity against filamentous ascomycetes occurring in cystic fibrosis patients and may offer a novel therapeutic option, especially for multidrug‐resistant S. prolificans.     

Evaluation of improvement of onychomycosis in HIV‐infected patients after initiation of combined antiretroviral therapy without antifungal treatment

Onychomycosis in HIV‐infected patients has a prevalence of 20–44% and is more frequently seen with CD4⁺ T cell counts ≤450 cel μl^?1. There are case reports of improvement in onychomycosis after initiation of combined antiretroviral therapy (cART), but there are no prospective studies that prove the existence and frequency of this phenomenon. The aim of this study was to evaluate if HIV‐infected patients with onychomycosis who begin cART improve and/or cure without antifungal treatment. We included HIV‐infected patients with onychomycosis who had not started cART and nor received antifungal therapy during 6 months prior to the study. We evaluated affected the nails with the Onychomycosis Severity Index (OSI); nail scrapings were collected and direct microscopy with potassium hydroxide (KOH) as well as mycological culture were performed. We repeated these procedures at 3 and 6 months to assess changes. CD4 T cell counts and HIV viral load were obtained. A total of 16 patients were included, with male gender predominance (68.7%); distal and lateral subungual onychomycosis (DLSO) was the most common form (31.3%). Trichophyton rubrum was the most frequently isolated microorganism. OSI decreased 21.5% at 3 months and 40% at 6 months after initiation of antiretrovirals (P = 0.05). We found a non‐significant tendency towards improvement with higher CD4⁺ T cell counts and with viral loads <100 000 copies ml^?1. This could be due to the increase in CD4⁺ T cells, decreased percentage of Treg (CD4⁺CD25⁺) among CD4⁺ Tcells and/or a decreased viral load; further studies are necessary to prove these hypothesis.     

In vitro evaluation of antifungal susceptibility and keratinase,elastase, lipase and DNase activities of different dermatophyte species isolated from clinical specimens in Iran

The aims of this study were to evaluate the enzymatic activity of various dermatophyte species and their antifungal susceptibility profiles. A total of 60 dermatophyte isolates, including Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis and Microsporum gypseum, were examined. Fungal isolates were analysed for the production of keratinase, lipase, elastase and deoxyribonuclease (DNase). A broth microdilution method was performed on the basis of M38‐A2 Clinical and Laboratory Standards Institute (CLSI) guidelines. T. mentagrophytes, M. canis and M. gypseum isolates were capable of producing keratinase, lipase, elastase and DNase, while T. rubrum isolates were elastase negative. The highest mean diameter of the clear zone around the colonies (PZ) was associated with keratinase (PZ: 4.56 ± 1.29 mm), followed by lipase (PZ: 1.53 ± 0.90 mm), DNase (PZ: 0.65 ± 0.54 mm) and elastase (PZ: 0.22 ± 0.27 mm) (P < 0.05). The mean minimum inhibitory concentration 90 (MIC₉₀) of all strains were as follows: itraconazole (MIC₉₀: 0.28 ± 0.31 μg ml^?1), ketoconazole (MIC₉₀: 0.48 ± 0.51 μg ml^?1), griseofulvin (MIC₉₀: 0.86 ± 1.00 μg ml^?1) and fluconazole (MIC₉₀: 18.57 ± 20.10 μg ml^?1). Dermatophyte isolates had higher keratinolytic activity than other enzymes. Itraconazole was the most effective antifungal drug and fluconazole had the poorest activity.     

Antifungal activity of tri‐ and tetra‐thioureido amino derivatives against different Candida species

The in vitro antifungal activity of six thioureido substituted amines (P1–P6) was evaluated against Candida species, including Candida albicans, C. glabrata, C. krusei and C. parapsilosis. These tri‐ and tetra‐thioureido amino derivatives with different methylation levels were synthesised through easy synthetic routes to evaluate their antifungal properties against Candida species. Among all studied derivatives, the tri‐(2‐thioureido‐ethyl)‐amine (P1) was the most active compound inhibiting C. albicans and C. glabrata at a concentration of 0.49 μg ml^?1; P3, the N,N′,N′′,N′′′‐hexamethyl‐derivative, also showed inhibitory activity against C. albicans and C. glabrata, but in higher concentrations (250 μg ml^?1). The N,N′,N′′,N′′′‐tetramethylated amine (P5) only inhibited the growth of C. glabrata, but its corresponding N,N′,N′′,N′′′‐octamethyl derivative (P6) was also active against C. glabrata (125 μg ml^?1) and it was the only compound active against C. parapsilosis. P2 and P4 showed no significant antifungal activity. The structure–activity relationship of the thioureido‐substituted derivatives indicates that the molecular branching and the alkylation levels can influence the antifungal activity. This study demonstrated that thioureido derivatives exhibited significant antifungal activity against Candida species and that they can be considered as a very promising bioactive lead compound to develop novel antifungal agents.     

In vitro efficacy of amphotericin B, 5‐fluorocytosine,fluconazole, voriconazole and posaconazole against Candida dubliniensis isolates using time‐kill methodology

Candida dubliniensis is a recently described yeast that causes infections in mucosal surfaces as well as sterile body sites. Candida dubliniensis develops resistance to fluconazole (FLC) more rapidly than the closely related species C. albicans. The killing activity of amphotericin B (AMB), 5‐fluorocytosine (5FC), FLC, voriconazole (VRC) and posaconazole (POS) was determined against six C. dubliniensis clinical isolates, identified using molecular biological methods and C. dubliniensis CD36 reference strain. Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute standard procedure. Time‐kill assays were performed using RPMI‐1640 as test media over a 48‐h period. AMB proved to be fungicidal at ≥0.5 μg ml^?1 against all clinical isolates after 48 h. 5FC was only fungicidal at 32–64× MIC (4–8 μg ml^?1) against all C. dubliniensis isolates. FLC, VRC and POS were fungistatic; decrease in colony number was observed only at the highest concentrations tested (8, 4 and 4 μg ml^?1, respectively). Triazoles invariably showed fungistatic effect at concentrations attainable in the serum. In clinical situations when a fungicidal antifungal is desirable, AMB may be used.     

Silver enhances the in vitro antifungal activity of the saponin,CAY‐1

The fungicidal properties of purified CAY‐1, dissolved silver ion and ethylenediamine tetraacetic acid (EDTA) separately were studied in vitro as were the abilities of silver and EDTA to enhance CAY‐1 fungicidal properties. Non‐germinated and germinating conidia of Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium verticillioides (Fusarium moniliforme), Fusarium oxysporum and Fusarium solani were incubated separately with CAY‐1 (0–24.8 μg ml^?1), silver (0–111.1 μg ml^?1), and EDTA (0–2400 μg ml^?1). Controls consisted of non‐germinated or germinated conidia in test medium. To assess combined activity, compounds, based on the sub‐lethal doses of each as defined in the initial experiments, were combined and tested in bioassays. Controls for the mixed sets consisted of non‐germinated or germinated conidia only or with the sub‐lethal CAY‐1 test concentrations. The minimum inhibitory concentrations (MICs) for CAY‐1 and silver, both separate and combined, were determined. Viability assays showed CAY‐1 activity only against the germinating conidia of A. flavus, A. niger and F. solani. Silver was active against the germinating conidia of all fungi and the non‐germinated conidia of F. oxysporum and F. solani. Combined silver and CAY‐1 produced significant viability loss at concentrations not effective separately. EDTA was not fungicidal separately and did not enhance CAY‐1 fungicidal properties. MIC data showed that CAY‐1 plus silver had an additive effect. Results indicate that dissolved silver was fungicidal in vitro and enhanced the fungicidal properties of CAY‐1 at concentrations ineffective when tested separately.     

Intraocular caspofungin: in vitro safety profile for human ocular cells

Endogenous Candida endophthalmitis is sight‐threatening, difficult to treat and sometimes leads to loss of the eye. Only a few therapeutic agents are available for its treatment. Caspofungin is the first of a new class of antifungal drugs (echinocandins) with a high activity against Candida species, the most common pathogens found in endogenous endophthalmitis. This study investigates the safety profile of caspofungin for intraocular application in a cell‐culture model. Endothelial toxicity of caspofungin was evaluated in cultured human corneas. Possible toxic effects of caspofungin (5–300 μg ml^?1) in corneal endothelial cells (CEC), primary human trabecular meshwork cells (TMC) and primary human retinal pigment epithelium (RPE) cells were evaluated after 24 h and under conditions of inflammatory stress by treatment with tumour necrosis factor‐alpha (TNF‐α), lipopolysaccharides (LPS) or interleukin‐6 (IL‐6) and hydrogen peroxide (H₂O₂). Toxicity was evaluated by tetrazolium dye‐reduction assay; cell viability was quantified by a microscopic live–dead assay. No corneal endothelial toxicity could be detected after 30 days of treatment with 75 μg ml^?1 of caspofungin. Concentrations up to 75 μg ml^?1 had no influence on CEC, TMC or RPE cell proliferation, or on cell viability when administered for 24 h. Exposure to H₂O₂ did not increase cellular toxicity of caspofungin at concentrations of 5–50 μg ml^?1. After preincubation with TNF‐α, LPS or IL‐6 for 24 h followed by treatment with caspofungin for 24 h, no significant decrease in cell proliferation or viability was observed. This study showed no significant toxicity for caspofungin on CEC, TMC or RPE cells, or human corneal endothelium when administered in therapeutic concentrations up to 50 μg ml^?1.     

Comparison of the in vitro activity of terbinafine and lanoconazole against dermatophytes

The objective of this study was to compare the antifungal activity of terbinafine (TERB) with that of lanoconazole (LAN). Test isolates, which were clinical isolates of Japanese origin, included 10 strains each of Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum. The minimum inhibitory concentration (MIC) of TERB and LAN against each dermatophyte isolate was determined according to the Clinical and Laboratory Standards Institute microbroth methodology, M38‐A2. Minimum fungicidal concentrations were determined by subculturing the contents of each visibly clear well from the MIC assay for colony count. All LAN MICs were ≤0.008 μg ml^?1, while the TERB range was 0.008–0.03 μg ml^?1. Moreover, by standard definition, LAN was fungistatic against most strains, whereas TERB was fungicidal. Both LAN and TERB demonstrated potent antifungal activity against dermatophytes; however, the lack of fungicidal activity by LAN needs to be evaluated in terms of potential clinical efficacy.     

The Mediterranean red alga Asparagopsis taxiformis has antifungal activity against Aspergillus species

The red algae Asparagopsis taxiformis collected from the Straits of Messina (Italy) were screened for antifungal activity against Aspergillus species. EUCAST methodology was applied and extracts showed antifungal activity against A. fumigatus, A. terreus and A. flavus. The lowest minimum inhibitory concentrations observed were <0.15 mg ml^?1 and the highest were >5 mg ml^?1 for Aspergillus spp. tested. Agar diffusion assays confirmed antifungal activity of A. taxiformis extracts in Aspergillus species.     

In vitro susceptibility of Aspergillus spp. to dithiocarbamate organoruthenium compounds

The in vitro antifungal activity of ruthenium dithiocarbamate compounds ( 1 – 5 ) was investigated and assessed for its activity against seven different species of Aspergillus (Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus nomius, Aspergillus tamarii and Aspergillus terreus). Analysis of in vitro susceptibility was performed using broth microdilution assay following the Clinical and Laboratory Standards Institute guidelines for filamentous fungi. The cytotoxicity was evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Aspergillus clavatus and A. fumigatus were more susceptible species for complexes 1 and 2 . Other complexes showed excellent minimum inhibitory concentration (4–64 μg ml^?1) against most microorganisms. Complexes 1 and 2 are respectively 180‐ and 95‐fold more active than the corresponding free ligands against A. clavatus and the complex 5 is 46‐fold more active than free ligand against A. niger. Aspergillus niger was more susceptible to the action of the complexes 1 and 5 (16 μg ml^?1). A low cytotoxic activity (IC₅₀ > 10^?6 mol l^?1) on normal mammalian cells (BHK‐21) to the evaluated complexes was measured. Ruthenium complexes are promising antifungal agents against the development of novel effective drug against different species of Aspergillus; however, for A. nomius and A. terreus, they were not active in the highest concentration tested.     

The inhibitory effects of aureobasidin A on Candida planktonic and biofilm cells

Aureobasidin A (AbA) is a cyclic depsipeptide antifungal compound that inhibits a wide range of pathogenic fungi. In this study, the in vitro susceptibility of 92 clinical isolates of various Candida species against AbA was assessed by determining the planktonic and biofilm MICs of the isolates. The MIC₅₀ and MIC₉₀ of the planktonic Candida yeast were 1 and 1 μg ml^?1, respectively, whereas the biofilm MIC₅₀ and MIC₉₀ of the isolates were 8 and ≥64 μg ml^?1 respectively. This study demonstrates AbA inhibition on filamentation and biofilm development of C. albicans. The production of short hyphae and a lack of filamentation might have impaired biofilm development of AbA‐treated cells. The AbA resistance of mature Candidia biofilms (24 h adherent population) was demonstrated in this study.     

Investigation of minor species Candida africana,Candida stellatoidea and Candida dubliniensis in the Candida albicans complex among Yaoundé (Cameroon) HIV‐infected patients

Minor species of the Candida albicans complex may cause overestimation of the epidemiology of C. albicans, and misidentifications could mask their implication in human pathology. Authors determined the occurrence of minor species of the C. albicans complex (C. africana, C. dubliniensis and C. stellatoidea) among Yaoundé HIV‐infected patients, Cameroon. Stool, vaginal discharge, urine and oropharyngeal samples were analysed by mycological diagnosis. Isolates were identified by conventional methods and mass spectrometry (MS; carried out by the matrix‐assisted laser desorption–ionisation time‐of‐flight MS protocol). Candida albicans isolates were thereafter submitted to the PCR amplification of the Hwp1 gene. The susceptibility of isolates to antifungal drugs was tested using the Clinical and Laboratory Standards Institute M27‐A3 protocol. From 115 C. albicans obtained isolates, neither C. dubliniensis nor C. stellatoidea was observed; two strains of C. africana (422PV and 448PV) were identified by PCR electrophoretic profiles at 700 bp. These two C. africana strains were vaginal isolates. The isolate 448PV was resistant to ketoconazole at the minimal inhibitory concentration of 2 μg ml^?1, and showed reduced susceptibility to amphotericin B at 1 μg ml^?1. This first report on C. africana occurrence in Cameroon brings clues for the understanding of the global epidemiology of this yeast as well as that of minor species of the C. albicans complex.     

Minimum inhibitory concentrations of amphotericin B against Candida krusei isolates from a French teaching hospital laboratory: a retrospective study over 8 years

Recent studies have shown decreased susceptibility of Candida krusei to amphotericin B (AmB), in addition to its inherent resistance to fluconazole. The susceptibility of C. krusei to AmB was studied in the Parasitology–Mycology laboratory of Grenoble Teaching Hospital, France. Between 2003 and 2011, we analysed 200 C. krusei isolates from 130 patients. The isolates were mainly collected in intensive care, cardio‐thoracic and cancer/haematology units. Minimum inhibitory concentrations (MICs) were determined by the E‐test method. The modal MIC was 0.5 μg ml^?1; the MIC₅₀ and MIC₉₀ (MICs encompassing 50% and 90% of all isolates tested, respectively) were 0.5 μg ml^?1 and 1 μg ml^?1. The Cuzick’s and Kendall’s tests showed a significant increase in MIC values between 2003 and 2011 (P = 0.001 and P ≤ 0.001, respectively), regardless of age or gender. No statistical difference was reached with these tests when the first 100 or 50 data were excluded. Despite the increase observed in the first period of the study, our results confirm the low AmB MICs reported in previous studies. However, some authors have recently reported much higher MICs. This discrepancy cannot be explained by method biases and could reflect C. krusei epidemiological differences among populations.     

Is further screening of men with baseline PSA < 1 ng ml−1 worthwhile? The discussion continues—Results of the Swiss ERSPC (Aarau)

Recent studies indicate frequent early PSA retesting unrelated of men's baseline PSA, which increases the harms of early detection especially among men with low PSA. The current study investigates the PCa incidence among men with baseline PSA <1.0 ng ml^?1 in order to adjust retest intervals for more targeted early detection. Between 1998 and 2012, 2,416 men with baseline PSA <1.0 ng ml^?1 were prospectively observed. Primary endpoint was PCa diagnosis. Negative predictive value (NPV) and number needed to screen (NNS) to detect one PCa were calculated. During a median follow‐up time of 12.1 years, 54 (2.2%) PCa were diagnosed with n = 26 (48.1%) among men with baseline PSA of 0.75 ≤ 1.0 ng ml^?1 (upper baseline PSA quartile). The 10‐year probability of being diagnosed with PCa increased significantly from 0.19% (baseline PSA < 0.40 ng ml^?1) to 2.0% (baseline PSA 0.40 ≤ 0.56 ng ml^?1), 2.5% (baseline PSA 0.56 ≤ 0.75 ng ml^?1) over 4.4% (baseline PSA 0.75 ≤ 1.0 ng ml^?1) (all p values <0.0001), respectively. The frequency of Gleason ≥7 PCa increased from 1 (0.17%) to 8 (1.4%), 5 (0.8) over 11 (1.8%) in these groups. The 8‐year NPV for Gleason ≥ 7 PCa were 99.8 (baseline PSA < 0.40 ng ml^?1), 99.8 (baseline PSA 0.40 ≤ 0.56 ng ml^?1), 100 (baseline PSA 0.56 ≤ 0.75 ng ml^?1) and 99.5 (baseline PSA 0.75 ≤ 1.0 ng ml^?1), respectively. During 12 years, the numbers were 99.8, 98.6, 99.2, and 98.2, respectively. Therefore, due to the very low rate of Gleason ≥ 7 PCa, further screening might be omitted in men with baseline PSA < 0.4 ng ml^?1. Between 0.4 and 1.0 ng ml^?1, an 8‐year interval can be discussed.     

Evaluation of anti‐Candida potential of geranium oil constituents against clinical isolates of Candida albicans differentially sensitive to fluconazole: inhibition of growth,dimorphism and sensitization

Fluconazole (FLC) susceptibility of isolates of Candida spp., (n = 42) and efficacy as well as mechanism of anti‐Candida activity of three constituents of geranium oil is evaluated in this study. No fluconazole resistance was observed among the clinical isolates tested, however 22% were susceptible‐dose‐dependent (S‐DD) [minimal inhibitory concentration (MIC) ≥16 μg ml^?1] and a standard strain of C. albicans ATCC 10231 was resistant (≥64 μg ml^?1). Geraniol and geranyl acetate were equally effective, fungicidal at 0.064% v/v concentrations i.e. MICs (561 μg ml^?1 and 584 μg ml^?1 respectively) and killed 99.9% inoculum within 15 and 30 min of exposures respectively. Citronellol was least effective and fungistatic. C. albicans dimorphism (Y→H) was highly sensitive to geranium oil constituents tested (IC50 approximately 0.008% v/v). Geraniol, geranyl acetate and citronellol brought down MICs of FLC by 16‐, 32‐ and 64‐fold respectively in a FLC‐resistant strain. Citronellol and geraniol arrested cells in G1 phase while geranyl acetate in G2‐M phase of cell cycle at MIC₅₀. In vitro cytotoxicity study revealed that geraniol, geranyl acetate and citronellol were non‐toxic to HeLa cells at MICs of the C. albicans growth. Our results indicate that two of the three geranium oil constituents tested exhibit excellent anti‐Candida activity and significant synergistic activity with fluconazole.     

Antifungal activity of bis‐azasqualenes,inhibitors of oxidosqualene cyclase

The antifungal activity and in vitro toxicity toward animal cells of two inhibitors of oxidosqualene cyclase, squalene bis‐diethylamine (SBD) and squalene bis‐diethylmethylammonium iodide (SBDI) were studied. Minimum inhibitory concentration (MIC) against dermatophytes and other fungi involved in cutaneous and systemic infections (12 isolates from seven species) were determined by the broth microdilution method based on the reference documents M38‐A and M27‐A2 of Clinical and Laboratory Standards Institute (CLSI). Both compounds exerted fungistatic activities, although with different action. SBDI was the more active compound and displayed low MIC values (in the 3.12–12.5 μg ml^?1 range) against Microsporum canis, Trichophyton mentagrophytes and one isolate of Scopulariopsis brevicaulis, while SBD showed MIC values against these species in the 3.12–25 μg ml^?1 range. Toxicity was tested on Madin‐Darby canine kidney (MDCK) epithelial cells and human microvascular endothelial cells (HMEC). SBDI proved the less toxic compound: it inhibited M. canis, T. mentagrophytes and S. brevicaulis at concentrations below those found toxic for MDCK cells. HMEC were the more sensitive cells.     

An anti‐Aspergillus protein from Escherichia coli DH5α: Putative inhibitor of siderophore biosynthesis in Aspergillus fumigatus

An antifungal protein designated as anti‐Aspergillus protein (AAP), produced by Escherichia coli DH5α, was purified and characterised. It exhibited a molecular weight of 60 kDa on Sodium dodecyl sulphate–polyacrylamide gel electrophoresis analysis and depicted 99% purity on ultra performance liquid chromatography. The purified protein manifested antimycotic potential against pathogenic isolates of Aspergillus spp., depicting a minimum inhibitory concentration in the range 15.62–31.25 μg ml^?1 and 5.0–10.0 μg per disc, using microbroth dilution, spore germination inhibition and disc diffusion assays respectively. In vitro toxicity tests demonstrated that it showed no toxicity against human erythrocytes at doses up to 1000 μg ml^?1. Matrix‐assisted laser desorption ionisation–Time‐of‐flight analysis of trypsin‐digested peptides of purified protein and subsequent Mascot search revealed that several peptides of AAP have identity with bacterial siderophore biosynthetic protein, i.e. non‐ribosomal peptide synthetase enzyme, involved in critical step of fungal siderophore biosynthesis. Siderophore‐based inhibition was further corroborated by Chrome azurol S assay. Hence, the antagonistic effect might be the result of impediment in siderophore‐mediated iron uptake and transport process which may cause critical consequences on Aspergillus growth and virulence.     

Antifungal activity of miconazole against recent Candida strains

Miconazole (MICON) has long been used for the topical treatment of mucosal candidiasis. However, the preponderance of MICON susceptibility data was generated before standard methodology was established, and prior to the emergence of fluconazole (FLU)‐resistant strains. The objective of this study was to determine the antifungal activity of MICON and comparators against recent clinical isolates of Candida spp. using standard Clinical and Laboratory Standards Institute methodology. One hundred and fifty isolates, consisting of 25 strains each of Candida albicans, C. krusei, C. glabrata, C. tropicalis, C. parapsilosis and C. dubliniensis, were tested. Of these, twenty‐two strains were known to be FLU‐resistant. Minimum inhibitory concentrations (MICs) were determined for MICON, amphotericin B (AM), caspofungin (CAS), clotrimazole (CLOT), FLU, itraconazole (ITRA), nystatin (NYS) and voriconazole (VOR). MICON demonstrated potent inhibitory activity against all of the strains tested. The MIC₉₀ for MICON was 0.12 μg ml^?1 against FLU‐susceptible strains, which was comparable to that of AM, CAS, CLOT, ITRA and VOR. The MICON MIC₉₀ against FLU‐resistant strains was 0.5 μg ml^?1, which was 12‐fold lower than the FLU MIC₉₀. Our study showed that MICON possesses potent activity against all of the Candida isolates tested, including those with known FLU resistance. This indicates that recent clinical isolates remain susceptible to this antifungal and that MICON could be used as first‐line treatment for oropharyngeal candidiasis.