Effect of benomyl and diazinon on acquired azole resistance in Aspergillus flavus and expression of mdr1 and cyp51c genes.

BACKGROUND AND PURPOSE: Aspergillus flavus is an important pathogen in immunodeficient patients. Due to the abundance of this fungus in nature, fungicides are commonly used to preserve and maintain agricultural products. Long-term exposure to these pesticides can lead to the induction of drug resistance in this fungus. MATERIALS AND METHODS: For the purpose of the study, 10 strains of A. flavus ATCC 204304 were cultured in benomyl and diazinon pesticides at the concentrations of 62.5, 125, 250.500, 750, 1000, 1500, 2000, and 2500 mg/L in nine steps. Morphological changes and resistance to voriconazole, itraconazole, and amphotericin B were evaluated at the end of each step. Subsequently, changes in the expression of mdr1 and cyp51C genes were studied in the strains showing drug resistance. RESULTS: The results showed that during the nine stages of the adjacency of strains with benomyl and diazinon at different concentrations, resistance to voriconazole, itraconazole, and amphotericin B in these toxins increased by 30% and 10%, respectively. In addition, the microscopic examination of resistant strains revealed the absence of sporulation, and only mycelium was found. Macroscopically, the color of the colonies changed from green to white. Furthermore, the investigation of the expression of mdr1 and cyp51c genes in these strains showed a decrease and increase in adjacency with diazinon and benomyl, respectively. CONCLUSION: As the findings indicated, exposure to agricultural pesticides can lead to the incidence of morphological changes and resistance to amphotericin B, itraconazole, and voriconazole in the sensitive species of A. flavus by altering the expression of genes involved in drug resistance.

Genetic diversity and antifungal susceptibility of Candida albicans isolated from Iranian patients.

A total of 105 independent Candida albicans strains isolated from patients in Iran were investigated. According to CLSI documents M27-A3 and M27-S4, the 24 h geometric mean MICs of caspofungin, itraconazole, and fluconazole were 0.27, 3.19, and 11.91 µg/ml, respectively. Microsatellites analysis of CEF3, CAIII, LOC4 Loci identified 93 different allelic genotypes clustered apart into six different clades. Antifungal susceptibility was not linked with the source of isolation and the corresponding genotype of C. albicans strains.

Inhibitory effect of vitamin C on Aspergillus parasiticus growth and aflatoxin gene expression.

BACKGROUND AND PURPOSE: Aflatoxin is known as one of the most important mycotoxins threatening human life. This toxin is produced by Aspergillus species, which is the common cause of agricultural product contamination. The use of organic compounds has been always considered for the inhibition of fungal growth and toxin production. Regarding this, the aim of the present study was to investigate the effect of vitamin C on the rate of fungal growth, aflR gene expression, and toxin production. MATERIALS AND METHODS: For the purpose of the study, first, Aspergillus parasiticus ATCC15517 was cultured in Sabouraud dextrose agar medium containing vitamin C at concentrations of 200, 100, 50, 25, 12.5, 6.25, and 3.1 mg/ml and temperature of 28°C for 72 h. Then, the amount of aflatoxin produced in the presence of vitamin C was measured through high performance liquid chromatography. Finally, by extracting the DNA of the cultured samples, the aflR gene expression level was evaluated by means of real-time polymerase chain reaction at different concentrations of vitamin C. RESULTS: The results showed that mycelium deformation was started at the vitamin C concentration of 50 mg/ml, and that only fungal spores were observed at higher concentrations. The levels of total aflatoxin and its subsets, namely B1, B2, G1, and G2, in the presence of vitamin C were estimated as 5.9, 1.9, 0.2, 3.5, and 0.3 ppm, respectively. On the other hand, these values were respectively obtained as 207.5, 73.6, 4.5, 123.4, and 6 ppm in the absence of vitamin C. Measurement of the expression level of aflR genes showed that the level of gene expression decreased to 68% and up to 81% at the vitamin C concentrations of 25 and 50 mg/ml, respectively. CONCLUSION: This study showed that vitamin C, as a human-compatible compound, could be considered a good agent to protect agricultural products against fungal aflatoxin.

In Vitro Assay of Paecilomyces lilacinus Biocontrol Effects on Fasciola hepatica Eggs Illustrated in Scanning Electron Micrographs.

BACKGROUND: Fascioliasis is a zoonotic disease caused by the liver fluke Fasciola hepatica. Drug resistance, high costs of treatment and economic losses in meat production have emerged the need of alternative control measures into consideration. The aim of this study was to evaluate the in vitro ovicidal activity of Paecilomyces lilacinus fungus on F. hepatica eggs. METHODS: P. lilacinus isolated from the soil of natural environment was challenged on F. hepatica eggs to observe the bio control effect of nematophagous fungi on trematode helminth eggs. The study was conducted in Tehran University of Medical Sciences, in 2015. Within 21 d of experiment, destructive effects exhibited on the eggshells were investigated using optical and Scanning Electron Microscopy. RESULTS: The effective role of P. lilacinus on damaging the eggs of F. hepatica was noticed. CONCLUSION: This finding is promising for advantageous use of nematophagus fungi as a natural constituent in hyper endemic areas for certain helminthic infections like fascioliasis with diverse kinds of herbivores as egg passer hosts.

The Utilization of RNA Silencing Technology to Mitigate the Voriconazole Resistance of Aspergillus Flavus; Lipofectamine-Based Delivery.

Purpose: Introducing the effect of RNAi in fungi to downregulate essential genes has made it a powerful tool to investigate gene function, with potential strategies for novel disease treatments. Thus, this study is an endeavor to delve into the silencing potentials of siRNA on cyp51A and MDR1 in voriconazole-resistant Aspergillus flavus as the target genes. Methods: In this study, we designed three cyp51A-specific siRNAs and three MDR1-specific siRNAs and after the co-transfection of siRNA into Aspergillus flavus, using lipofectamine, we investigated the effect of different siRNA concentrations (5, 15, 25, 50nM) on cyp51A and MDR1 expressions by qRT-PCR. Finally, the Minimum Inhibitory Concentrations (MICs) of voriconazole for isolates were determined by broth dilution method. Results: Cyp51A siRNA induced 9, 22, 33, 40-fold reductions in cyp51A mRNA expres-sion in a voriconazole-resistant strain following the treatment of the cells with concentrations of 5, 15, 25, 50nM siRNA, respectively. Identically, the same procedure was applied to MDR1, even though it induced 2, 3, 4, 10-fold reductions. The results demonstrated a MIC for voriconazole in the untreated group (4µg per ml), when compared to the group treated with cyp51A-specific siRNA and MDR1-specific siRNA, both at concentrations of 25 and 50nM, yielding 2µg per ml and 1µg per ml when 25 nM was applied and 2µg per ml and 0.5µg per ml when the concentration doubled to 50 nM. Conclusion: In this study, we suggested that siRNA-mediated specific inhibition of cyp51A and MDR1 genes play roles in voriconazole-resistant A.flavus strain and these could be apt target genes for inactivation. The current study promises a bright prospect for the treatment of invasive aspergillosis through the effective deployment of RNAi and gene therapy.

Quantitative Analysis of Single-Nucleotide Polymorphism for Rapid Detection of TR34/L98H- and TR46/Y121F/T289A-Positive Aspergillus fumigatus Isolates Obtained from Patients in Iran from 2010 to 2014.

We employed an endpoint genotyping method to update the prevalence rate of positivity for the TR34/L98H mutation (a 34-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with a substitution at codon L98) and the TR46/Y121F/T289A mutation (a 46-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with substitutions at codons Y121 and T289) among clinical Aspergillus fumigatus isolates obtained from different regions of Iran over a recent 5-year period (2010 to 2014). The antifungal activities of itraconazole, voriconazole, and posaconazole against 172 clinical A. fumigatus isolates were investigated using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. For the isolates with an azole resistance phenotype, the cyp51A gene and its promoter were amplified and sequenced. In addition, using a LightCycler 480 real-time PCR system, a novel endpoint genotyping analysis method targeting single-nucleotide polymorphisms was evaluated to detect the L98H and Y121F mutations in the cyp51A gene of all isolates. Of the 172 A. fumigatus isolates tested, the MIC values of itraconazole (≥16 mg/liter) and voriconazole (>4 mg/liter) were high for 6 (3.5%). Quantitative analysis of single-nucleotide polymorphisms showed the TR34/L98H mutation in the cyp51A genes of six isolates. No isolates harboring the TR46/Y121F/T289A mutation were detected. DNA sequencing of the cyp51A gene confirmed the results of the novel endpoint genotyping method. By microsatellite typing, all of the azole-resistant isolates had genotypes different from those previously recovered from Iran and from the Dutch TR34/L98H controls. In conclusion, there was not a significant increase in the prevalence of azole-resistant A. fumigatus isolates harboring the TR34/L98H resistance mechanism among isolates recovered over a recent 5-year period (2010 to 2014) in Iran. A quantitative assay detecting a single-nucleotide polymorphism in the cyp51A gene of A. fumigatus is a reliable tool for the rapid screening and monitoring of TR34/L98H- and TR46/Y121F/T289A-positive isolates and can easily be incorporated into clinical mycology algorithms.

Evaluation of mRNA Expression Levels of cyp51A and mdr1, Candidate Genes for Voriconazole Resistance in Aspergillus flavus.

BACKGROUND: Voriconazole Resistance (VRC-R) in Aspergillus flavus isolates impacts the management of aspergillosis, since azoles are the first choice for prophylaxis and therapy. However, to the best of our knowledge, the mechanisms underlying voriconazole resistance are poorly understood. OBJECTIVES: The present study was designed to evaluate mRNA expression levels of cyp51A and mdr1 genes in voriconazole resistant A. flavus by a Real-Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) technique. MATERIALS AND METHODS: Five A. flavus isolates with resistance to VRC were examined by a RT-PCR approach. RESULTS: Four out of five isolates revealed cyp51A and mdr1 mRNA overexpression. Interestingly, the isolate, which was negative for cyp51A and mdr1 mRNA expression showed a high voriconazole Minimum Inhibitory Concentration (MIC). Furthermore, a computational-based analysis predicted that voriconazole resistance could be mediated through cooperation with a network protein interaction. CONCLUSIONS: Our experimental and in silico findings may provide new insight in the complex molecular pathways of drug resistance and also could assist design an efficient therapeutic strategy for aspergillosis treatment.

Identification and Sequencing of Candida krusei Aconitate Hydratase Gene Using Rapid Amplification of cDNA Ends Method and Phylogenetic Analysis.

BACKGROUND: The production and development of an effective fungicidal drug requires the identification of an essential fungal protein as a drug target. Aconitase (ACO) is a mitochondrial protein that plays a vital role in tricarboxylic acid (TCA) cycle and thus production of energy within the cell. OBJECTIVES: The current study aimed to sequence Candida krusei ACO gene and determine any amino acid residue differences between human and fungal aconitases to obtain selective inhibition. MATERIALS AND METHODS: Candida krusei (ATCC: 6258) aconitase gene was determined by 5'Rapid Amplification of cDNA Ends (RACE) method and degenerate Polymerase Chain Reaction (PCR) and analyzed using bioinformatics softwares. RESULTS: One thousand-four hundred-nineteen nucleotide of C. krusei aconitase gene were clarified and submitted in Genbank as a partial sequence and then taxonomic location of C. krusei was determined by nucleotide and amino acid sequences of this gene. The comparison of nucleotide and amino acid sequences of Candida species ACO genes showed that C. krusei possessed characteristic sequences. No significant differences were observed between C. krusei and human aconitases within the active site amino acid residues. CONCLUSIONS: Results of the current study indicated that aconitase was not a suitable target to design new anti-fungal drugs that selectively block this enzyme.

Effects of low-level laser irradiation on the pathogenicity of Candida albicans: in vitro and in vivo study.

OBJECTIVE: The purpose of this study was to evaluate the effects of low-level laser irradiation (LLLI) on the in vitro growth characteristics and in vivo pathogenicity of Candida albicans in a murine model in the absence of a photosensitizer. BACKGROUND DATA: C. albicans is an opportunistic commensal organism that causes a wide variety of diseases in human beings, ranging from superficial infections to life-threatening invasive candidiasis. The incidence of C. albicans infection is increasing, because of the greater frequency of acquired immunodeficiency conditions. A high recurrence rate has been reported for vulvovaginal and oral candidiasis, despite the best available treatments. Therefore, the search for new treatment modalities seems quite rational. METHODS: Candida culture plates were exposed to common clinical energies of LLLI: 3, 5, 10, and 20 J at 685 nm (BTL Laser 5000, Medicinos Projektai, Czech Republic, Prague, max power output 50 mW) and 3, 5, 10, 30, and 50 J at 830 nm (BTL Laser 5000, Medicinos Projektai, Czech Republic, Prague, max power output 400 mW). RESULTS: Following LLLI with energies >10 J at both 685 and 830 nm wavelengths, statistically significant effects were observed in vitro on the turbidimetric growth kinetics of C. albicans and in vivo on the survival rate of infected mice (p value ≤ 0.05). Therefore, this energy could be considered a threshold for clinical investigation. CONCLUSIONS: Translating our data into the clinical setting, it can be proposed that a direct laser-based approach without using a photosensitizing dye can significantly reduce the pathogenicity of Candida albicans. It can also be concluded that laser light at specific wavelengths could be a possible promising novel treatment for superficial and mucocutaneous C. albicans infections.

Giardia intestinalis: DNA extraction approaches to improve PCR results.

Difficulty in disrupting cysts of Giardia intestinalis, a cosmopolitan protozoan parasite, decreases the yield of DNA extracted and reduces the effectiveness of the polymerase chain reaction (PCR). To improve the detection of the Giardia Glutamate Dehydrogenase (gdh) gene, we re-evaluated the effects of deoxyribonucleic acid (DNA) extraction methods. Purified and concentrated cysts from 33 fecal samples were disrupted using conventional methods, and DNA extraction was conducted using two protocols: the QIAamp Stool Mini Kit and phenol/chloroform/isoamyl alcohol (PCI). PCR amplification was successful for 12 extracted DNA samples (36%) using PCI following a glass bead and freeze/thaw pretreatment and for all 33 samples (100%) using the QIAamp Stool Mini Kit following the aforementioned pretreatment. Consequently, the pretreatment of cysts with glass beads and freeze/thaw cycles followed by extraction of DNA with the QIAamp Stool Mini kit was the more effective protocol.

First report of a mixed infection due to Acanthamoeba genotype T3 and Vahlkampfia in a cosmetic soft contact lens wearer in Iran.

Acanthamoeba keratitis cases have emerged in the recent years in Iran. In this case, an amoebic keratitis due to a mixed infection with Acanthamoeba and Vahlkampfia species is reported. Corneal scrapes, contact lenses and contact lens cases obtained from the patient were analysed and were positive for cysts of Acanthamoeba and Vahlkampfia genera. Genus-specific PCR was carried out for both genera, confirming the microscopic observations. To our knowledge, this is the first reported case of a possible mixed amoebic infection due to Acanthamoeba and Vahlkampfia and raises awareness within contact lens wearers in Iran.

High-level expression of lipase in Escherichia coli and recovery of active recombinant enzyme through in vitro refolding.

Microbial lipases are widely used for biotechnological applications. In this study we have cloned and sequenced the lipase and lipase specific foldase genes of a Pseudomonas sp., which was isolated from Southern Iran. The lipase was composed of 936 bp which encoded 311 amino acids and the lipase specific foldase gene consisted of 1008 bp which encoded 336 amino acids. The low amount of recombinant lipase was expressed as an active enzyme in Escherichia coli harboring a plasmid with the clustered lipase and lipase specific foldase genes. To increase the enzyme expression level, the lipase and lipase specific foldase genes subcloned into two separate expression vectors. The lipase was expressed as inactive inclusion bodies under the control of the strong T7 promoter. Inclusion bodies were dissolved in 8M urea and 1mM dithiothreitol (DTT) and purified using Ni-nitrilotriacetic acid column. Subsequently, purified lipase diluted in 20mM phosphate buffer (pH 7) containing the lipase specific foldase which was expressed in another clone of E. coli. In the presence of foldase, it was possible to achieve active lipase with a specific activity of up to 240 IU/mg using a simple refolding procedure. Moreover, the effect of different concentrations of various additives was investigated on the refolding of denatured lipase. The best yield of 70 IU/ml with the specific activity of 3000 IU/mg were obtained after incubation of denatured enzyme in a refolding buffer containing lipase specific foldase (0.005 mg/ml), 1M NaCl and 10% glycerol at 4 degrees C.

Genotyping of Acanthamoeba isolates from clinical and environmental specimens in Iran.

In this study, 15 Acanthamoeba isolates from AK patients and 10 environmental samples (water, soil and animal-origin samples) were classified at the genotype level based on the sequence analysis of the Diagnostic Fragment 3 (DF3) of Acanthamoeba small subunit rRNA gene. The obtained results revealed that most of these Acanthamoeba strains belonged to genotype T4 both in clinical and environmental samples. The presence T11 genotype in clinical samples was also revealed after the genotyping analysis and to our knowledge this is the first report of T11 genotype in Iran. Moreover, the isolation of T4 genotype from cow faeces in this study highlights a possible transmission of Acanthamoeba through animal faeces in Iran. Overall, the widespread distribution of pathogenic Acanthamoeba T4 across the environmental sources and the increasing number of contact lens wearers in Iran, demands more awareness within the public and health professionals as this pathogen is emerging as a risk for human health in Iran and worldwide.

Detection of Toxoplasma gondii from sera and urine of experimentally infected mice by PCR.

Toxoplasms gondii was detected in sera and urine of acutely infected mice. Animals were inoculated intraperitoneally with tachyzoites of T. gondii, RH strain. Ten animals were killed every day from day 1 up to day 7 post infection. Urine and sera of animals were collected and stored at -20 degree C until use. PCR performed by B1 gene amplification. Toxoplasma was detected in sera from 3 days post infection and in urine from 5 days post infection. No parasite was detected in control group.

Molecular characterization of Cryptosporidium isolates from humans and animals in Iran.

Isolates of Cryptosporidium spp. from human and animal hosts in Iran were characterized on the basis of both the 18S rRNA gene and the Laxer locus. Three Cryptosporidium species, C. hominis, C. parvum, and C. meleagridis, were recognized, and zoonotically transmitted C. parvum was the predominant species found in humans.

Cryptosporidium parvum bovine genotype oocysts in the respiratory samples of an AIDS patient: efficacy of treatment with a combination of azithromycin and paromomycin.

Cryptosporidium has been recognized as an emerging zoonotic agent of intestinal cryptosporidiosis leading to diarrhea, malabsorption syndrome, and weight loss in AIDS patients. In the present case, oocysts of zoonotic Cryptosporidium parvum were detected in the sputum and stool samples of an AIDS patient with a 3-month history of intestinal cryptosporidiosis. The oocysts were detected by modified Ziehl-Neelsen staining; confirmation was achieved by nested polymerase chain reaction (PCR), targeting the most polymorphic region of the 18S rRNA gene. Genotyping was done by restriction endonuclease digestion of the PCR product. The zoonotic C. parvum bovine genotype was identified in both intestinal and respiratory samples. Treatment with both azithromycin and paromomycin resulted in improvement of both intestinal and respiratory symptoms, as well as the elimination of the parasite. This is the first report of the identification of Cryptosporidium sp. oocysts in the respiratory samples obtained from an AIDS patient in Iran. Pulmonary cryptosporidiosis should be considered whenever an AIDS patient with intestinal cryptosporidiosis develops respiratory symptoms.