Given the increasing incidence of yeast infections and the presence of drug-resistant isolates, accurate identification of the pathogenic yeasts is essential for the management of yeast infections. In this review, we tried to introduce the routine and novel techniques applied for yeast identification. Laboratory identification methods of pathogenic yeast are classified into three categories; I. conventional methods, including microscopical and culture-base methods II. biochemical/physiological-processes methods III. molecular methods. While conventional and biochemical methods require more precautions and are not specific in some cases, molecular diagnostic methods are the optimum tools for diagnosing pathogenic yeasts in a short time with high accuracy and specificity, and having various methods that cover different purposes, and affordable costs for researchers. Nucleotide sequencing is a reference or gold standard for identifying pathogenic yeasts. Since it is an expensive method, it is not widely used in developing countries. However, novel identification techniques are constantly updated, and we recommend further studies in this field. The results of this study will guide researchers in finding more accurate diagnostic method(s) for their studies in a short period of time.
Background and Objectives: There is a poor understanding about the prevalence and characteristics of secondary bacterial and fungal infections among Coronavirus diseases 2019 (COVID-19) superinfection in hospitalized patients. Materials and Methods: Four hundred COVID-19-proven patients were enrolled in this study. Nasal swabs for molecular assay (Real-time PCR) and sputum samples for further microbiological assays were collected. Following a broad-spectrum search, a meta-analysis was performed using StatsDirect software (version 2.7.9) according to the DerSimonian and Laird method applying the random-effects models. Results: Streptococcus spp. (21.5%) and Staphylococcus spp. (16.7%) had the highest prevalence of bacterial coinfection among the COVID-19 patients, while Acinetobacter spp. had the lowest prevalence (4.2%). Among fungal coinfections, Candida albicans was the most prevalent (6.7%), and Aspergillus spp. was the lowest (2%). Males, elderly patients, patients with a history of underlying diseases and drug use, patients who showed acute clinical symptoms, and patients with a prolonged hospital stay had a higher incidence of secondary infections (P-value <0.05). The pooled prevalence for bacterial and fungal coinfections was 33.52% (95% CI: 18.12 to 50.98; I2: 99.4%; P-value: <0.0001). Conclusion: We suggest designing additional research with a larger target population and diagnostic molecular analyses to depict a more realistic view of the coinfection status.
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.
BACKGROUND AND PURPOSE: Aspergillosis is one of the most common opportunistic fungal infections in immunocompromised and neutropenic patients. Aspergillus fumigatus (A. fumigatus) is the most common causative agent of this infection. Due to variable CO2 concentrations that pathogens are exposed to during the infection process and to understand the role of CO2, we examined the effects of various CO2 concentrations as one of the environmental factors on morphological changes and induction of antifungal resistance in A. fumigatus. MATERIALS AND METHODS: A. fumigatus strains were cultured and incubated under 1%, 3%, 5%, and 12% CO2 atmospheres, each time for one, two, and four weeks. The control culture was maintained for one week without CO2 atmosphere. Morphological changes were investigated and antifungal susceptibility test was performed according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI) M38-A2 document. The results of different CO2 atmospheres were compared with that of the control sample. RESULTS: We found that 1%, 3%, 5%, and 12% CO2 atmospheres were associated with morphological colony changes. Macroscopically, the colonies were shallow dark green, smooth, crisp to powdery with reduced growth; microscopic examination revealed the absence of conidiation. The induction of antifungal resistance in the susceptible strains to itraconazole, voriconazole, and amphotericin B increased after exposure to 12% CO2 atmosphere and four weeks of incubation. The MIC values for itraconazole, voriconazole, and amphotericin B were 16 g/ml, 1 g/ml, and 16 g/ml, respectively. These values for the control group were 0.125 g/ml, 0.125 g/ml, and 2 g/ml, respectively. CONCLUSION: Exposure to different CO2 atmospheres induced morphological changes in A. fumigatus, it seems to increase the MIC values, as well. In parallel, resistance to both itraconazole and voriconazole was also observed.
BACKGROUND: Soil and effluent of lead and zinc industries contain high concentration of cadmium. The present study was conducted to isolate tolerant fungal strains from cadmium -polluted sites in Zanjan province, Iran. METHODS: Cadmium tolerance and bioremediation capacity of seven isolates including Aspergilus versicolor, Aspergillus fumigatus, Paecilomyces sp.9, Paecilomyces sp.G, Terichoderma sp, Microsporum sp,Cladosporium sp were determined. RESULTS: Minimum inhibitory concentration values among 1,000-4,000 mg l-(1)proved great ability of isolated strains to survive in cadmium polluted environments. The most tolerant fungi, Aspergilus versicolor, showed tolerance index of 0.8 in 100 mg l-(1) cadmium agar media. Fungal resistance against cadmium is depended directly on strain's biological function. A. versicolor was found to bioaccumulate over7 mg of cadmium per 1 g of mycelium, followed by 5.878, 5.243, and 5.075, 4.557 by Paecilomyces sp, Aspergilus fumigatus, Microsporum sp and Terichoderma sp, respectively. CONCLUSION: It can be noted that tolerance of the strains appears to be independent from bioaccumulation capacity. Finally, the results indicated that A. versicolor could be a prospective candidate for bioremediation processes.
