Current Medical Mycology最新文献

Background and purpose: The human mouth mucosal surface is colonized by indigenous microflora, which normally maintains an ecological balance among different species. However, certain environmental or biological factors may disrupt this balance, leading to microbial diseases. Candida albicans biofilms are formed on indwelling medical devices and have an association with both oral and invasive candidiasis. This study aimed to compare the amount of adherent C. albicans and the biofilm formed on different denture base materials. The adhesion of C. albicans to denture base materials is widely recognized as the main reason for the development of denture stomatitis.

Materials and methods: In total, 56 polymethyl methacrylate (PMMA) acrylic resin disc-shaped samples were divided into four groups as follows: 1) chemically polymerized PMMA, 2) heat-polymerized PMMA, 3) computer-aided design and computer-aided manufacturing (CAD/CAM) PMMA in high polish, and 4) CAD/CAM resins in glazed form. The adherent cells and formation of C. albicans strains (562, 1905, 1912, and 1949) biofilm were measured by the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) method and use of a microplate reader. Moreover, morphological alterations of C. albicans cells were investigated using scanning electron microscopy (SEM).

Results: The biofilm formation was significantly lower on CAD/CAM acrylic resins, compared to conventional denture base materials. The obtained results were confirmed by the SEM images of C. albicans biofilms. CAD/CAM PMMA-based polymers may be preferable to inhibit C. albicans biofilm formation and reduce Candida-associated denture stomatitis in long-term use.

Conclusion: Based on the findings, the CAD/CAM technique can be used as an efficient technique for denture fabrication as it inhibits microbial accumulation, and consequently, microbial biofilm.

Background and purpose: Candidemia is known as an invasive fungal infection with high mortality. The prevalence of candidemia in intensive care unit (ICU) patients is more than in other hospital wards. Early diagnosis of candidemia in these patients is essential for disease management.

Materials and methods: This study included 250 patients suspected of candidemia. Blood samples were taken from patients and incubated. The fungal isolates were identified by PCR-RFLP method using MSP I restriction enzyme. Demographic characteristics, risk factors, underlying diseases, and laboratory analysis results were mined in this study.

Results: In total, 22 blood samples were identified as positive for Candida yeasts in culture. The most common underlying diseases in these patients were heart disease and hypertension (36.4%). Candida albicans with 12 cases (54.5%) was the most isolated species, followed by C. parapsilosis (n=5, 22.7%), C. glabrata (n=4, 18.2%), and C. tropicalis (n=1, 4.5%) in descending order. Intravenous catheter use was recognized as the most common risk factor in patients with candidemia (77.3%), and after that, the use of mechanical ventilation (68.2%) and urinary catheter (40.9%) obtained the highest frequency. Furthermore, 17 patients were prescribed at least one antifungal drug, of which fluconazole was the most used (36.4%). The mortality rate in patients in this study was 63.6%. All C. albicans isolates were susceptible to antifungal agents but in non-albicans Candida (NAC), drug resistance to fluconazole, voriconazole, and caspofungin were observed.

Conclusion: Although C. albicans was the most common fungal species in this study, the prevalence of NAC species was high. The increasing frequency of NAC species is a concern because they have different patterns of drug resistance. Recognition of risk factors in patients admitted to ICUs can help prevent candidemia or properly manage the disease.

Background and purpose: Invasive candidiasis is one of the most common systemic mycoses, and studies have shown mixed yeast infections. Malaysia lacks mixed yeast culture data.

Materials and methods: Yeast isolates were collected in Sultan Abdul Halim Hospital, North Malaysia, from October 2020 to October 2021. Chromogenic Candida differential agar media and PCR-RFLP were used to identify yeast species.

Results: A total of 206 yeast isolates were collected from different body sites of patients. The majority of the yeast isolates (n=104) were obtained from the urine. Other isolates were extracted from blood (n=52), vaginal swabs (n=45), ear discharge (n=2), tracheal aspirate (n=2), tissue (n=2), skin (n=1), nail (n=1), sputum (n=1), and cerebrospinal fluid (n=1). In total, 200 yeast samples were identified as single species, and six isolates were a mixture of Candida species.

Conclusion: Malaysia lacks accurate epidemiological data on mixed yeast infections. We identified all samples to the species level, including mixed yeast cultures, using the MspI enzyme and PCR-RFLP.

Background and purpose: Infections by emerging and multiresistant Candida species are becoming more frequent throughout the world. This study aimed to describe Candida species in different wards of a tertiary hospital in Honduras.

Materials and methods: The prevalence of species within the C. albicans complex was estimated using a molecular approach, and C. auris was investigated using a yeast pool-based DNA extraction method. In total, 328 yeast isolates were identified using phenotypic approaches. For the identification of species within the C. albicans complex, a molecular approach based on the size polymorphisms of the hpw1 gene was used. In addition, a technique was optimized based on DNA extraction in pools for the rapid identification of C. auris.

Results: A total of 11 species of Candida were identified in the hospital wards. C. albicans showed the highest number of isolates (52.4%). Within the C. albicans complex, C. albicans sensu stricto was the most common, followed by C. dubliniensis. However, C. auris was not found.

Conclusion: Reports on the distribution of Candida species in Honduras are limited; accordingly, the data from this study are of importance for a better understanding of their epidemiology. Moreover, a simple method was offered for the detection of C. auris that could help in its detection in low-resource settings.

Background and purpose: Fungus Ball (FB) is a non-invasive fungal infection caused mainly by Aspergillus species. It can occur after root canal treatments are applied to the teeth adjacent to the maxillary sinus. These balls are commonly seen in the paranasal sinuses and rarely observed in the nasal cavity. This report attempted in to highlight such a rare case of fungal infection which requires accurate observation. Moreover, it highlights the importance of careful microbiological and histopathological examinations that were combined with imaging and can lead to a definitive diagnosis.

Case report: Herein, we report a rare case of a FB found in the vicinity of the nasal cavity of a 73-year-old male patient. Microbiological examination supported by radiographic and histopathological results indicated that the FB is due to Aspergillus niger. Excised surgery was done to the FB area, and the patient was referred to the post-operation room with the proper recommendations. After the wound healed, the total denture was performed as requested by the patient, and his overall oral health was improved.

Conclusion: In this article, we report the first case of a rare FB in the vicinity of the nasal cavity of a 73-year-old male patient. The appropriate investigation is an essential step in the diagnostic process for these infections and requires effective communication and collaboration.

Since its first emergence in December 2019, due to its fast distribution throughout the world, SARS-COV-2 become a global concern. With the extremely increased number of hospitalized patients, this situation provided a potential basis for the transmission of nosocomial infections. Candida auris is a multidrug-resistant pathogen with improved transmission dynamics and resistance traits. During the worldwide spread of COVID-19, cases or outbreaks of C. auris colonization or infection have been reported. Resistance to antifungal drugs has been observed in the causative agents of the majority of such cases. The focus in this review is on COVID-19-associated C. auris infections (case studies/outbreaks) and the pandemic's potential effect on antifungal drug resistance.

Background and purpose: Candidiasis is regarded as one of the most important fungal infections and a cause of disease and mortality in patients with hematological malignancy. Accordingly, antifungal prophylaxis is of significant importance in this regard. This study aimed to identify the epidemiology of Candida colonization and evaluate its antifungal susceptibility pattern in patients with hematological malignancy.

Materials and methods: In this study, the samples were collected from the oral cavity of 100 patients, and Candida colonization was confirmed by fungal culture. Candida strains were also identified by ITS-PCR. In vitro antifungal susceptibility tests against fluconazole, amphotericin B, and caspofungin were performed according to CLSI M60.

Results: Demographic characteristics, comorbidities, distribution of Candida species (spp.), and antifungal susceptibility were analyzed in this study. The study participants included 100 patients with a mean age of 15.48%±48.74 years (age range: 17-84 years). Regarding gender distribution, the majority (64%) of the patients were male. In terms of the distribution of underlying hematologic malignancy, 27% of the cases had lymphoma. The most commonly isolated species among patients were C. albicans complex (49%; n=49), C. glabrata (39%; n=39), and co-colonization of C. albicans complex and C. with C. glabrata (10%; n=10). The overall resistance of C. albicans complex was 5% to fluconazole (n=5) and 2% to amphotericin B (n=2). Furthermore, C. glabrata showed 11% (n=11) resistance to fluconazole and was susceptible to amphotericin B. All Candida spp. isolated from patients who were susceptible to caspofungin.

Conclusion: The high rate of colonization of Candida spp., especially the significant increase in the frequency of C. glabrata in patients with blood malignancies and the gradual increase in resistance to fluconazole, necessitate a change in the use of antifungal drugs for the prevention and experimental treatment of hematological malignancy.

Background and purpose: Vulvovaginal candidiasis (VVC) is considered the most common mucosal infection caused by Candida species. Azoles were considered the first-line treatment for VVC or recurrent vulvovaginal candidiasis (RVVC) in both healthy and immunocompromised populations. Recently, azole-resistant isolates, especially among non-albicans Candida samples have been encountered. This study aimed to evaluate the antifungal susceptibility profile of Candida spp. isolated from VVC or RVVC patients and assess the molecular resistance mechanism of Candida spp. to azole and echinocandin.

Materials and methods: Point mutation analysis was performed on the ERG11 and FKS candidate genes of azole- and caspofungin-resistant Candida albicans and Candida glabrata isolates. Real-time polymerase chain reaction was performed to gain insight into the differential expression of ERG11 mRNA.

Results: Variations in the amino acid D116E were observed in fluconazole- and itraconazole-resistant C. albicans strains, and changes in amino acid E517Q were observed only in fluconazole-resistant C. albicans strains. No polymorphisms were observed in the complete sequence alignment of the ERG11 gene in one azole-resistant C. glabrata isolate. The mutation triggered the changes in the amino acid serine in the reference gene FKS1 by the leucine at position 642 (S642L) of the isolates.

Conclusion: In patients with persistent or recurrent infection, the choice of an antifungal agent is often challenging and requires monitoring of the antifungal susceptibility of the colonizing strain. C. albicans and C. glabrata isolates can be resistant to azole and caspofungin antifungal agents without mutations in the ERG 11 and HS1 regions of the FKS1 gene.

Background and purpose: Oropharyngeal candidiasis is the most prevalent opportunistic fungal infection in patients with human immunodeficiency virus (HIV) as well as other immunodeficiency disorders, which is caused by various Candida species, mostly Candida albicans. Studies have shown that Candida isolates differ in their pathogenicity. These variations are attributed to virulence factors, host characteristics, and the target tissue. This study aimed to determine and compare the secretion of hydrolytic enzymes in C. albicans and non-albicans Candida species isolated from HIV⁺/AIDS patients and healthy individuals.

Materials and methods: Samples were taken from 201 patients with HIV and 118 healthy individuals. The samples were identified by macroscopic, phenotypic, and molecular methods, and virulence factors were subsequently measured. Statistical differences in enzymatic activity of various Candida isolates were calculated (P<0.0001).

Results: In total, 95 samples (47.20%) from patients and 46 samples (38.90%) from healthy individuals were positive for the growth of different Candida species. There were 39 (41.10%) and 36 (78.30%) C. albicans in patients and healthy individuals, respectively, as well as 56 (58.90%) and 10 (21.70%) non-albicans species in patients and healthy subjects, respectively. All the enzymes produced by Candida species enzymes were at low, medium, and high levels. Hemolysin activity in Candida species isolated from patients was significantly higher, compared to healthy individuals. Moreover, the activity of all C. albicans enzymes in patients was significantly higher than other Candida species.

Conclusion: The C. albicans isolated from HIV-positive individuals secreted higher amounts of exoenzymes, and can cause oropharyngeal candidiasis and become a source of candidiasis for the host.

Background and purpose: This study aimed to evaluate the species distribution and susceptibility pattern of the strains isolated from Candida colonization in pediatric patients staying at pediatric intensive care unit (ICU) and infant ICU of Children's Medical Center in Tehran, Iran.

Materials and methods: This study was conducted in the Children's Medical Center in Tehran, Iran. In total, 440 samples from 56 patients with oral cavity, skin surrounded catheters, and ear, throat, nasal, and urine cultures were collected. All patients were evaluated in terms of Candida colonization on the admission day as well as the days 7, 14, and 28 according to the previous studies. CHROMagar Candida medium was applied for primary/multiple species identification and the isolates were identified by using polymerase chain reaction-based methods to the species-specific complex level. The antifungal susceptibility test was performed according to the Clinical and Laboratory Standards protocol published as M27-A3 and M60 documents.

Results: In total, 136 yeast samples from 26 individuals (30.9%) out of 440 samples were considered colonization. The most prevalent species in IICU was C. albicans (27%, n=20) followed by C. krusei (24 %, n=18) and C. parapsilosis (16%, n=12). In PICU, the predominant species was C. krusei (40%, n=24) followed by C. parapsilosis (18%, n=11) and C. dubliniensis (16%, n=10). Among the 40 tested isolates from both units, fluconazole-resistant isolates (n=11, 8.15%) were determined according to the new breakpoints. In the case of echinocandins, 2 isolates, including C. albicans (n=1) and C. krusei (n=1) were resistant against both caspofungin and anidulafungin (totally 1.48%).

Conclusion: In the present study, since C. krusei is intrinsically-resistance against fluconazole, emphasizing the importance of species-level identification of Candida isolates is outstanding. However, according to the antifungal susceptibility testing results, only 7.2% of the strains were resistant to fluconazole. It would be beneficial to monitor the ICU patients who are at high risk of invasive Candida infection.