Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: 10.5-year analysis of susceptibilities of noncandidal yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing

Identification of Trichosporon yeast isolates from superficial infections in male patients from Central Brazil: an approach to the diversity of infections caused by this basidiomycete fungus

The genus Trichosporon are currently recognized as opportunistic pathogens capable of causing superficial "white piedra" infections and potentially fatal invasive diseases (Trichosporonosis). In this work, determine the agent Trichosporon spp. isolated from the skin and appendages of a male population group in the Central-West region of Brazil. The isolates were analyzed by phenotypic, biochemical and molecular methods. Twenty-five strains of Trichosporon were isolated: T. asahii (18; 72%), followed by T. inkin (4; 16%) and T. faecale (3; 12%). Skin infections were the most affected (16; 64%) and the genitocrural region (13; 52%) was the most affected. The highest rate of isolation occurred between the ages of 21 and 30 years (9; 36%), with black men (African descent) (13; 52%) being the most affected by this type of superficial infection. After the advent of molecular techniques, more than 50 subspecies and about 16 different strains have been reported to cause human disease. In this series, three species of the genus Trichosporon of medical importance were highlighted, colonizing the genital and perigenital region of the studied population. For the identifications, classical phenotypic methods associated with genotypic identification were carried out, using molecular techniques based on the study of DNA; using sequence analysis of the DNA intergenic spacer region 1 (IGS1).

A review of the epidemiology of invasive fungal infections in Asian patients with hematological malignancies (2011-2021)

The incidence of invasive fungal infection (IFI) is increasing, especially among patients diagnosed with hematological malignancies due to their immunocompromised nature. Other risk factors include advanced age, exposure to immunosuppressants, neutropenia, and catheter use. Some of the most common IFI organisms reported are Candida and Aspergillus species, and other fungal species, including Scedosporium, Trichosporon, Cryptococcus, and Fusarium have also increasingly been reported in the past years. However, the epidemiologic data on IFI among patients with hematological malignancies in Asian countries are lacking. Therefore, we investigated published epidemiologic data on such cases from the past 10 years (2011-2021) and discuss the challenges faced in the diagnosis and management of IFIs in Asia.

Epidemiology of cryptococcal meningitis and fluconazole heteroresistance in Cryptococcus neoformans isolates from a teaching hospital in southwestern China

Cryptococcal meningitis (CM), a common and serious opportunistic infection mostly caused by Cryptococcus neoformans, is primarily treated with fluconazole. Nevertheless, Cryptococcus neoformans strains that undergo repeated exposure to azoles can gradually acquire heteroresistance to fluconazole. The management of this specific CM infection poses a substantial challenge. Determining a globally accepted definition for fluconazole heteroresistance and developing effective and prompt methods for identifying heteroresistance is of utmost importance. We collected data on the clinical and epidemiological characteristics of patients diagnosed with CM. All the available Cryptococcus neoformans strains isolated from these patients were collected and subjected to antifungal susceptibility testing and evaluation of fluconazole heteroresistance. AIDS was present in 40.5% of the patients, whereas 24.1% did not have any underlying diseases. Patients with chronic diseases or impaired immune systems are susceptible to infection by Cryptococcus neoformans, a fungus that frequently (39.6%, 19/48) shows heteroresistance to fluconazole, as confirmed by population analysis profile (PAP).IMPORTANCEFluconazole heteroresistance poses a significant threat to the efficacy of fluconazole in treating cryptococcal meningitis (CM). Unfortunately, the standard broth microdilution method often misses the subtle percentages of subpopulations exhibiting heteroresistance. While the population analysis profile (PAP) method is esteemed as the gold standard, its time-consuming and labor-intensive nature makes it impractical for routine clinical use. In contrast, the Kirby-Bauer (KB) disk diffusion method offers a simple and effective screening solution. Our study highlights the value of KB over PAP and minimum inhibitory concentration (MIC) by demonstrating that when adjusting the inoculum concentration to 1.0 McFarland and subjecting samples to a 72-hour incubation period at 35°C, the KB method closely mirrors the outcomes of the PAP approach in detecting fluconazole heteroresistance. This optimization of the KB method not only enhances assay efficiency but also provides a blueprint for developing a timely and effective strategy for identifying heteroresistance.

Aneuploidy underlies brefeldin A-induced antifungal drug resistance in Cryptococcus neoformans

Cryptococcus neoformans is at the top of the list of "most wanted" human pathogens. Only three classes of antifungal drugs are available for the treatment of cryptococcosis. Studies on antifungal resistance mechanisms are limited to the investigation of how a particular antifungal drug induces resistance to a particular drug, and the impact of stresses other than antifungals on the development of antifungal resistance and even cross-resistance is largely unexplored. The endoplasmic reticulum (ER) is a ubiquitous subcellular organelle of eukaryotic cells. Brefeldin A (BFA) is a widely used chemical inducer of ER stress. Here, we found that both weak and strong selection by BFA caused aneuploidy formation in C. neoformans, mainly disomy of chromosome 1, chromosome 3, and chromosome 7. Disomy of chromosome 1 conferred cross-resistance to two classes of antifungal drugs: fluconazole and 5-flucytosine, as well as hypersensitivity to amphotericin B. However, drug resistance was unstable, due to the intrinsic instability of aneuploidy. We found overexpression of AFR1 on Chr1 and GEA2 on Chr3 phenocopied BFA resistance conferred by chromosome disomy. Overexpression of AFR1 also caused resistance to fluconazole and hypersensitivity to amphotericin B. Furthermore, a strain with a deletion of AFR1 failed to form chromosome 1 disomy upon BFA treatment. Transcriptome analysis indicated that chromosome 1 disomy simultaneously upregulated AFR1, ERG11, and other efflux and ERG genes. Thus, we posit that BFA has the potential to drive the rapid development of drug resistance and even cross-resistance in C. neoformans, with genome plasticity as the accomplice.

Comparison of fungemia caused by Candida and non-Candida rare yeasts: a retrospective study from a tertiary care hospital

Although Candida species are the most common cause of fungemia, non-Candida rare yeasts (NCY) have been increasingly reported worldwide. Although the importance of these yeast infections is recognized, current epidemiological information about these pathogens is limited, and they have variable antifungal susceptibility profiles. In this study, we aimed to evaluate the clinical characteristics for fungemia caused by NCY by comparing with candidemia. The episodes of NCY fungemia between January 2011 and August 2023 were retrospectively evaluated in terms of clinical characteristics, predisposing factor, and outcome. In addition, a candidemia group, including patients in the same period was conducted for comparison. Antifungal susceptibility tests were performed according to the reference method. A total of 85 patients with fungemia episodes were included: 25 with NCY fungemia and 60 with candidemia. Fluconazole had high minimal inhibitory concentration (MIC) values against almost all NCY isolates. The MIC values for voriconazole, posaconazole, and amphotericin B were ≤ 2 µg/ml, and for caspofungin and anidulafungin were ≥ 1 µg/ml against most of isolates. Hematological malignancies, immunosuppressive therapy, neutropenia and prolonged neutropenia, polymicrobial bacteremia/fungemia, preexposure to antifungal drugs, and breakthrough fungemia were associated with NCY fungemia, whereas intensive care unit admission, diabetes mellitus, urinary catheters, and total parenteral nutrition were associated with candidemia. In conclusion, the majority of fungemia due to NCY species was the problem, particularly in hematology units and patients with hematological malignancy. Preexposure to antifungal drugs likely causes a change in the epidemiology of fungemia in favor of non-albicans Candida and/or NCY.

Molecular Epidemiology and Antifungal Susceptibility Profile in Nakaseomyces glabrata Species Complex: A 5-Year Countrywide Study

BACKGROUND

The current study aimed to identify Iranian Nakaseomyces (Candida) glabrata complex species in the clinical isolates and determine their antifungal susceptibility profile.

METHODS

In total, 320 N. glabrata clinical isolates were collected from patients hospitalized in different geographical regions of Iran. The initial screening was performed by morphological characteristics on CHROMagar Candida. Each isolate was identified by targeting the D1/D2 rDNA using a multiplex-PCR method. To validate the mPCR method and determine genetic diversity, the ITS-rDNA region was randomly sequenced in 40 isolates. Additionally, antifungal susceptibility was evaluated against nine antifungal agents following the CLSI M27-A4 guidelines.

RESULTS

All clinical isolates from Iran were identified as N. glabrata. The analysis of ITS-rDNA sequence data revealed the presence of eight distinct ITS clades and 10 haplotypes among the 40 isolates of N. glabrata. The predominant clades identified were Clades VII, V, and IV, which respectively accounted for 22.5%, 17.5%, and 17.5% isolates. The widest MIC ranges were observed for voriconazole (0.016-8 μg/mL) and isavuconazole (0.016-2 μg/mL), whereas the narrowest ranges were seen with itraconazole and amphotericin B (0.25-2 μg/mL).

CONCLUSION

Haplotype diversity can be a valuable approach for studying the genetic diversity, transmission patterns, and epidemiology of the N. glabrata complex.

Complex Decisions in HIV-Related Cryptococcosis: Addressing Second Episodes of Cryptococcal Meningitis

PURPOSE OF REVIEW

This review highlights the difficulties in diagnosing and treating persons with a prior history of cryptococcal meningitis who improve but suffer from a recurrence of symptoms. This scenario is well known to those who frequently care for patients with cryptococcal meningitis but is not well understood. We highlight major gaps in knowledge.

RECENT FINDINGS

We recently summarized our experience with 28 persons with paradoxical immune reconstitution inflammatory syndrome (IRIS) and 81 persons with microbiological relapse. CD4 count and cerebrospinal fluid white blood cell count were higher in IRIS than relapse but neither was reliable enough to routinely differentiate these conditions. Second-episode cryptococcal meningitis remains a difficult clinical scenario as cryptococcal antigen, while excellent for initial diagnosis has no value in differentiating relapse of infection from other causes of recurrent symptoms. Updated research definitions are proposed and rapid, accurate diagnostic tests are urgently needed.

Minimum inhibitory concentrations of antifungals against invasive isolates of Cryptococcus species worldwide: Global antifungal antimicrobial testing leadership and surveillance program, 2010-2020

This study examined the geographic distribution of minimum inhibitory concentrations (MICs) of antifungals against Cryptococcus isolates. Data were collected on the MICs of specific antifungals (amphotericin B, 5-flucytosine, fluconazole, voriconazole, posaconazole, and isavuconazole) against various Cryptococcus species for the period 2010 to 2020 from the Antimicrobial Testing Leadership and Surveillance database. Cryptococcus isolates were collected from samples of blood and cerebrospinal fluid (CSF) from patients hospitalized in different regions worldwide. We applied the epidemiological cutoff values (ECVs) of antifungals against various Cryptococcus species to distinguish wild-type (WT) from non-WT Cryptococcus isolates. A total of 395 isolates of Cryptococcus species cultured from blood (n = 201) or CSF (n = 194) were analyzed. C. grubii (n = 270), C. neoformans (n = 111), and C. gattii (n = 11) were the three predominant species causing bloodstream infections (BSI) or meningitis/meningoencephalitis (MME). The proportion of MICs above the ECV (1 mg/L) for amphotericin B among C. neoformans isolates was significantly lower than that among C. gattii isolates (MICs >0.5 mg/L; P < 0.001), as evaluated using the chi-square test. For most isolates of the three predominant Cryptococcus species, the MICs of new triazoles were ≤0.25 mg/L. The MICs of fluconazole and amphotericin B in the BSI/MME-causing Cryptococcus isolates collected from patients hospitalized in the Asia-Western Pacific region and Europe were significantly lower (i.e., the distributions were more leftward) than those in North America and Latin America. Ongoing monitoring of MIC data for important antifungals against cryptococcosis is crucial.

In vitro activity of manogepix and comparators against infrequently encountered yeast and mold isolates from the SENTRY Surveillance Program (2017-2022)

Manogepix is a potent new antifungal agent targeting the fungal Gwt1 enzyme. Manogepix has previously demonstrated potent in vitro activity against clinical isolates of both Candida (except Candida krusei) and Aspergillus species. This study determined the in vitro activity of manogepix and comparators against a large collection of infrequently encountered yeast and molds. Manogepix demonstrated potent in vitro activity against infrequently encountered yeasts exhibiting elevated MIC values to other drug classes, including Candida spp. (MIC50/90, 0.008/0.12 mg/L), Saprochaete clavata (Magnusiomyces clavatus) (MIC50/90, 0.03/0.06 mg/L), Magnusiomyces capitatus (MICrange, 0.016-0.06 mg/L), Rhodotorula minuta (MIC, 0.016 mg/L), and Rhodotorula mucilaginosa (MIC50/90, 0.03/0.12 mg/L). Similarly, manogepix was active against infrequently encountered mold isolates and strains exhibiting elevated MIC/MEC values to echinocandins, azoles, and amphotericin B, including Coprinopsis cinerea (MEC, 0.004 mg/L), Fusarium spp. (MEC50/90, 0.016/0.06 mg/L), Fusarium (Gibberella) fujikuroi species complex (MEC50/90, 0.016/0.03 mg/L), Lomentospora prolificans (MEC50/90, 0.03/0.06 mg/L), Microascus cirrosus (MEC, 0.008 mg/L), Paecilomyces spp. (MEC50/90, ≤0.008/0.016 mg/L), Pleurostomophora richardsiae (MEC, 0.06 mg/L), Sarocladium kiliense (MEC range, 0.016-0.12 mg/L), and Scedosporium spp. (MEC50/90, 0.03/0.06 mg/L). Manogepix demonstrated potent activity against a majority of the infrequently encountered yeast and mold isolates tested including strains with elevated MIC/MEC values to other drug classes. Additional clinical development of manogepix (fosmanogepix) in difficult-to-treat, resistant fungal infections is warranted.

Genotypic diversity and antifungal susceptibility of Cryptococcus neoformans species complex from China, including the diploid VNIII isolates from HIV-infected patients in Chongqing region

Although previous studies on the genotypic diversity and antifungal susceptibility of the Cryptococcus neoformans species complex (CNSC) isolates from China revealed ST5 genotype isolates being dominant, the information about the CNSC isolates from Chinese HIV-infected patients is limited. In this study, 171 CNSC isolates from HIV-infected patients in the Chongqing region of Southwest China were genotyped using the International Society for Human and Animal Mycology-multilocus sequence typing consensus scheme, and their antifungal drug susceptibilities were determined following CLSI M27-A3 guidelines. Among 171 isolates, six sequence types (STs) were identified, including the dominant ST5 isolates, the newly reported ST15, and four diploid VNIII isolates (ST632/ST636). Moreover, a total of 1019 CNSC isolates with STs and HIV-status information were collected and analyzed from Mainland China in the present study. A minimum spanning analysis grouped these 1019 isolates into three main subgroups, which were dominated by the ST5 clonal complex (CC5), followed by the ST31 clonal complex (CC31) and ST93 clonal complex (CC93). The trend of resistance or decreasing susceptibility of clinical CNSC isolates to azole agents within HIV-infected patients from the Chongqing region is increasing, especially resistance to fluconazole.

Differences of clinical characteristics and outcome in proven invasive Trichosporon infections caused by asahii and non-asahii species

BACKGROUND

Trichosporon is an emerging yeast that causes invasive infections in immunocompromised patients experiencing prolonged hospitalisation, indwelling venous catheters and neutropenia.

METHODS

This retrospective observational cohort study analysed invasive Trichosporon infections (ITIs) occurring between January 2005 and December 2022 at three tertiary hospitals and compared the clinical characteristics and prognostic factors of ITIs caused by Trichosporon asahii and non-T. asahii spp. After evaluating 1067 clinical isolates, we identified 46 patients with proven ITIs, defined as cases in which Trichosporon was isolated from blood, cerebrospinal fluid, or sterile tissues.

RESULTS

The patients were separated into T. asahii and non-T. asahii groups containing 25 and 21 patients, respectively, all of which except one were immunocompromised. During this period, both the number of clinical isolates and patients with ITIs (mainly T. asahii) increased; whereas, cases involving non-T. asahii spp. decreased. Compared with the non-T. asahii group, the T. asahii group had more patients with multiple catheters (84% vs. 33%, p = .001) and those receiving renal replacement therapy (48% vs. 14%, p = .005). The all-cause 28-day mortality rate after ITI in the T. asahii group (44%) was significantly higher than in the non-T. asahii group (10%, Log-rank p = .014). The multivariate Cox regression model revealed that T. asahii (reference, non-T. asahii spp.; aHR = 4.3; 95% CI = 1.2-15.2, p = .024) and neutropenia for 5 days or more (aHR = 2.2, 95% CI = 1.5-3.6, p = .035) were independent factors in the 28-day mortality after ITI.

CONCLUSION

The proven ITIs due to T. asahii produced more unfavourable outcomes compared with ITIs caused by non-T. asahii spp.

Fungemia due to rare non-Candida yeasts between 2018 and 2021 in a Greek tertiary care university hospital

INTRODUCTION

Non-Candida yeasts, although rare, are increasingly encountered and recognized as a growing threat.

METHODS

Cases of bloodstream infections (BSIs) due to non-Candida yeasts (NCYs) during the last four years (2018-2021) are presented.

RESULTS

During the study period, 16 cases caused by non-Candida yeasts out of 400 cases of yeast BSIs were recorded, corresponding to an incidence of 4%. Yeasts that were isolated included Cryptococcus spp (4 isolates-25%), Rhodotorula mucilaginosa (2 isolates-12.5%), Trichosporon asahii (7 isolates-43.75%) and Saccharomyces cerevisiae (3 isolates-18.75%). Predisposing factors involved mostly hematological malignancies, long term hospitalization or major surgical interventions. Most isolates, 15 out of 16 were susceptible to amphotericin B. Voriconazole was the most active azole in vitro. All isolates, except Saccharomyces spp., were resistant to echinocandins.

DISCUSSION

Early recognition of rare yeasts as causative agents of BSIs and prompt initiation of appropriate treatment based on current guidelines and expertise remain crucial in efficient patient management.

Cryptococcosis in Southern China: Insights from a Six-Year Retrospective Study in Eastern Guangdong

Objective

Cryptococcosis is a fatal infection that can affect both immunocompetent and immunocompromised patients, and it is little understood in China's various regions. This research aimed to look at the epidemiology, risk factors, and antifungal susceptibility pattern of Cryptococcus neoformans in eastern Guangdong, China.

Methods

A six-year (2016-2022) retrospective study was conducted at Meizhou People's Hospital, China. Demographical, clinical, and laboratory data of cryptococcal patients were collected from hospital records and statistically analyzed using the chi-square and ANOVA tests.

Results

Overall, 170 cryptococcal infections were recorded, of which meningitis accounted for 78 (45.88%), cryptococcemia for 50 (29.41%), and pneumonia for 42 (24.7%). The number of cases increased 8-fold during the study duration. The median age of patients was 58 years (Inter quartile range: 47-66), and the high proportion of cases was from the male population (n = 121, 71.17%). The underlying diseases were identified only in 60 (35.29%) patients, of which 26 (15.29%) were severely immunocompromised, and 26 (15.29%) others were mildly immunocompromised. A statistically significant difference was reported for chronic renal failure, and anemia (p < 0.05) persisted in cases of three infection types. A high number of non-wild type (NWT) isolates were found against amphotericin B (n=13/145, 8.96%), followed by itraconazole (n=7/136, 5.15%) and voriconazole (n=4/158, 2.53%). Only six isolates (3.79%) were multidrug-resistant, four of which were from cryptococcemia patients. Compared to meningitis and pneumonia, cryptococcemia revealed a higher percentage of NWT isolates (p < 0.05).

Conclusion

In high-risk populations, cryptococcal infections require ongoing monitoring and management.

Differentiated extracts from freshwater and terrestrial mollusks inhibit virulence factor production in Cryptococcus neoformans

The human fungal pathogen, Cryptococcus neoformans, is responsible for deadly infections among immunocompromised individuals with the evolution of antifungal resistance driving the solution to discover new compounds that inhibit fungal virulence factors rather than kill the pathogen. Recently, exploration into natural sources (e.g., plants, invertebrates, microbes) of antifungal agents has garnered attention by integrating a One Health approach for new compound discovery. Here, we explore extracts from three mollusk species (freshwater and terrestrial) and evaluate effects against the growth and virulence factor production (i.e., thermotolerance, melanin, capsule, and biofilm) in C. neoformans. We demonstrate that clarified extracts of Planorbella pilsbryi have a fungicidal effect on cryptococcal cells comparable to fluconazole. Similarly, all extracts of Cipangopaludina chinensis affect cryptococcal thermotolerance and impair biofilm and capsule production, with clarified extracts of Cepaea nemoralis also conveying the latter effect. Next, inhibitory activity of extracts against peptidases related to specific virulence factors, combined with stress assays and quantitative proteomics, defined distinct proteome signatures and proposed proteins driving the observed anti-virulence properties. Overall, this work highlights the potential of compounds derived from natural sources to inhibit virulence factor production in a clinically important fungal pathogen.

Lack of Association between YEASTONE Antifungal Susceptibility Tests and Clinical Outcomes of Cryptococcus Meningitis

The relation between antifungal susceptibility and treatment outcomes is not well-characterized. There is paucity of surveillance data for cerebrospinal fluid (CSF) isolates of cryptococcus investigated with YEASTONE colorimetric broth microdilution susceptibility testing. A retrospective study of laboratory-confirmed cryptococcus meningitis (CM) patients was conducted. The antifungal susceptibility of CSF isolates was determined using YEASTONE colorimetric broth microdilution. Clinical parameters, CSF laboratory indices, and antifungal susceptibility results were analyzed to identify risk factors for mortality. High rates of resistance to fluconazole and flucytosine were observed in this cohort. Voriconazole had the lowest MIC (0.06 µg/mL) and lowest rate of resistance (3.8%). In a univariate analysis, hematological malignancy, concurrent cryptococcemia, high Sequential Organ Failure Assessment (SOFA) score, low Glasgow coma scale (GCS) score, low CSF glucose level, high CSF cryptococcal antigen titer, and high serum cryptococcal antigen burden were associated with mortality. In a multivariate analysis, meningitis with concurrent cryptococcemia, GCS score, and high CSF cryptococcus burden, were independent predictors of poor prognosis. Both early and late mortality rates were not significantly different between CM wild type and non-wild type species.

SARS-CoV-2 Post-Infection and Sepsis by Saccharomyces cerevisiae: A Fatal Case Report-Focus on Fungal Susceptibility and Potential Virulence Attributes

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for approximately 6.8 million deaths worldwide, threatening more than 753 million individuals. People with severe coronavirus disease-2019 (COVID-19) infection often exhibit an immunosuppression condition, resulting in greater chances of developing co-infections with bacteria and fungi, including opportunistic yeasts belonging to the Saccharomyces and Candida genera. In the present work, we have reported the case of a 75-year-old woman admitted at a Brazilian university hospital with an arterial ulcer in the left foot, which was being prepared for surgical amputation. The patient presented other underlying diseases and presented positive tests for COVID-19 prior to hospitalization. She received antimicrobial treatment, but her general condition worsened quickly, leading to death by septic shock after 4 days of hospitalization. Blood samples collected on the day she died were positive for yeast-like organisms, which were later identified as Saccharomyces cerevisiae by both biochemical and molecular methods. The fungal strain exhibited low minimal inhibitory concentration values for the antifungal agents tested (amphotericin B, 5-flucytosine, caspofungin, fluconazole and voriconazole), and it was able to produce important virulence factors, such as extracellular bioactive molecules (e.g., aspartic peptidase, phospholipase, esterase, phytase, catalase, hemolysin and siderophore) and biofilm. Despite the activity against planktonic cells, the antifungals were not able to impact the mature biofilm parameters (biomass and viability). Additionally, the S. cerevisiae strain caused the death of Tenebrio molitor larvae, depending on the fungal inoculum, and larvae immunosuppression with corticosteroids increased the larvae mortality rate. In conclusion, the present study highlighted the emergence of S. cerevisiae as an opportunistic fungal pathogen in immunosuppressed patients presenting several severe comorbidities, including COVID-19 infection.

Synergistic effect of pyrvinium pamoate and posaconazole against Cryptococcus neoformans in vitro and in vivo

Background

Cryptococcosis is a global invasive mycosis with high rates of morbidity and mortality, especially in AIDS patients. Its treatment remains challenging because of the limited antifungals and their unavoidable toxicity, and as such more efforts need to focus on the development of novel effective drugs. Previous studies have indicated that pyrvinium pamoate (PP) has individual and synergistic fungistatic effect. In this study, the effects of PP alone and in combination with azoles [fluconazole (FLU), itraconazole (ITR), voriconazole (VOR), posaconazole (POS)] or amphotericin B (AmB) were evaluated against Cryptococcus neoformans both in vitro and in vivo.

Methods

A total of 20 C. neoformans strains collected from cryptococcal pneumonia and cryptococcal meningitis were studied. The effects of PP alone, PP-azoles and PP-AmB interactions against C. neoformans were evaluated via the microdilution chequerboard technique, adapted from broth microdilution method according to the CLSI M27-A4. The in vivo antifungal activity of PP alone and in combination with azoles and AmB against C. neoformans infections was evaluated by Galleria mellonella survival assay.

Results

The in vitro results revealed that PP individually was ineffective against C. neoformans (MIC>16 μg/ml). Nevertheless, the synergistic effects of PP with ITR, VOR, POS, FLU or AmB was observed in 13 (65.0%, FICI 0.188-0.365), 3 (15.0%, FICI 0.245-0.301), 19 (95.0%, FICI 0.188-0.375), 7 (35.0%, FICI 0.188-0.375), and 12(60.0%, FICI 0.281-0.375) strains of C. neoformans, respectively. There was no antagonism. The survival rates of larvae treated with PP (3.33%) showed almost no antifungal effective, but the larvae survival rates improved when PP combined with AmB (35% vs. 23.33%), FLU (40% vs. 25%), ITR (48.33% vs. 33.33%), VOR (48.33% vs. 53.33%) and POS (56.67% vs. 36.67%) comparison with AmB or azoles alone, and statistical significance was observed when PP combined with POS versus POS alone (P = 0.04).

Conclusions

In summary, the preliminary results indicated the potential of PP in reduction the MICs of azoles and AmB, also itself against C. neoformans; the combination of PP with AMB, FLU, ITR, VOR and POS improve the survival rates of C. neoformans infection larvae, compared with they are alone. The in vitro and in vivo data show that PP could enhance the activity of POS against C. neoformans. This study contributes with data of PP in combination with classical drugs of choice for cryptococcosis treatment.

JMM Profile: Trichosporon yeasts: from superficial pathogen to threat for haematological-neutropenic patients

Trichosporon yeasts are classical agents of superficial mycoses, and they are ranked as the first to second predominant basidiomycetous yeast able to cause invasive infections. The clinical presentation of Trichosporon infections varies with the affected anatomical site, with fungaemia present in the majority of invasive trichosporonosis cases. Only a limited number of antifungal compounds can be used to treat Trichosporon infections. Azoles are the first choice due to their intrinsic resistance to echinocandins. Better laboratory methods and up-to-date databases of commercial platforms are required to improve identification, susceptibility testing and surveillance of this potentially threating infection.

Lack of Association between Fluconazole Susceptibility and ERG11 Nucleotide Polymorphisms in Cryptococcus neoformans Clinical Isolates from Uganda

Fluconazole is the drug of choice for cryptococcal meningitis (CM) monoprophylaxis in resource-limited settings such as Uganda. Emerging fluconazole resistance linked to mutations in the Cryptococcus neoformansERG11 gene (CYP51) has been observed in clinical isolates. Currently, the single nucleotide polymorphisms [SNPs] in the Cryptococcus spp. ERG11 gene that could be responsible for fluconazole resistance are poorly characterized within Ugandan C. neoformans clinical isolates. If available, this information would be useful in the management of cryptococcosis among HIV patients. This cross-sectional study investigates the SNPs present in the coding region of the C. neoformansERG11 gene to determine the relationship between the SNPs identified and fluconazole susceptibility of the clinical isolates. 310 C. neoformans isolates recovered from the Cerebrospinal Fluid (CSF) of patients with HIV and cryptococcal meningitis were examined. The fluconazole half-maximal inhibitory concentrations (IC50 range: 0.25−32 μg/mL) was determined using the microbroth dilution method. A total of 56.1% of the isolates had low IC50 values of <8 μg/mL while 43.9% had high IC50 values ≥ 8 μg/mL. We amplified and sequenced 600 bp of the ERG11 coding sequence from 40 of the clinical isolates. Novel synonymous and 2 missense mutations, S460T and A457V, were identified in the ERG11 gene. The identified SNPs were not associated with differences in fluconazole IC50 values in vitro (p = 0.179).

Drug Resistance and Biofilm Formation in Candida Species of Vaginal Origin

BACKGROUND

Candida species are normal vaginal flora in healthy women, which can cause vulvovaginal candid-iasis (VVC). The formation of biofilm is a cause of drug resistance in Candida species of vaginal origin. We aimed to specify Candida species cause VVC, detect their biofilm-forming ability, and antifungal susceptibility pattern.

METHODS

Overall 150 vaginal samples were collected from suspected cases of referring to Bahar Hospital of Shahroud, Iran between Jan 2018 and Jan 2019. Samples were cultured on Sabouraud dextrose agar (SDA), Chrome gar Candida and Corn meal agar (CMA). PCR-RFLP was performed to confirm the identification. Bio-film formation of the identified species was measured by the Crystal Violet method. The susceptibility to fluconazole, clotrimazole, and miconazole was determined based on the CLSI document M27-A3.

RESULTS

Of 50 women (33.3%) were suffering from VVC. C.albicans was the predominant species isolated in this study (n=39, 78%) followed by C. glabratia (n=11, 22%). In addition, in 25 (50%) of positive samples, bio-film formation was determined. The mean MIC of fluconazole and clotrimazole for C. albicans was 5.02 μg/mL and 3.92 μg/mL, respectively. Furthermore, the mean MIC related to these drugs for C. glabrata was 12.45 μg / mL and 4.1μg / mL, respectively. The mean diameter of miconazole inhibition zone for C. albicans and C. glabra isolates was 25.13 mm and 24.5mm, respectively and all of them were susceptible to this drug.

CONCLUSION

C.albicans was the predominant Candida species isolated from patients with VVC and also was the predominant biofilm producer species.

Isolation of Candida auris in Clinical Specimens

Candida auris is a multidrug-resistant yeast causing healthcare-associated outbreaks of blood stream infections worldwide. Currently, C. auris isolation and identification is complicated by issues such as misidentification and long turnaround time associated with application of commonly used diagnostic tools. Based on phenotypic characteristics, differentiation of C. auris from related Candida haemulonii complex spp. is problematic. Candida auris can be misidentified using biochemical-based systems such as VITEK 2 YST, API 20C, BD Phoenix yeast identification system, and MicroScan. C. auris growth at 42 °C and in the presence of 10% NaCl helps in presumptive identification of this yeast from related Candida haemulonii complex spp. A new CHROMagar™ Candida Plus agar is an excellent alternative to current conventional mycological media for the screening of patients colonized/infected with Candida auris. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) can differentiate C. auris from other Candida species, but not all the reference databases included in MALDI-TOF devices allow for detection. Currently, accurate identification of C. auris can be performed using the updated FDA-approved libraries or "research use-only" libraries. Molecular techniques have greatly enhanced the diagnosis of C. auris. Sequencing of rDNA genetic loci, namely, internal transcribed spacer and D1/D2 region of large subunit (LSU), and PCR/qPCR assays has successfully been applied for identification of C. auris. Real-time PCR assays bear incomparable potential of being the most efficient tool for high-throughput screening of surveillance samples. If properly validated, they can deliver the diagnostic result within several hours, since the DNA can be isolated directly from the patient specimen without the need of obtaining a colony. In this chapter we detailed the isolation of Candida auris from various clinical specimens and its currently available identification methods and hitches.

Global guideline for the diagnosis and management of rare yeast infections: an initiative of the ECMM in cooperation with ISHAM and ASM

Uncommon, or rare, yeast infections are on the rise given increasing numbers of patients who are immunocompromised or seriously ill. The major pathogens include those of the genera Geotrichum, Saprochaete, Magnusiomyces, and Trichosporon (ie, basidiomycetes) and Kodamaea, Malassezia, Pseudozyma (ie, now Moesziomyces or Dirkmeia), Rhodotorula, Saccharomyces, and Sporobolomyces (ie, ascomycetes). A considered approach to the complex, multidisciplinary management of infections that are caused by these pathogens is essential to optimising patient outcomes; however, management guidelines are either region-specific or require updating. In alignment with the One World-One Guideline initiative to incorporate regional differences, experts from diverse geographical regions analysed publications describing the epidemiology and management of the previously mentioned rare yeasts. This guideline summarises the consensus recommendations with regards to the diagnostic and therapeutic options for patients with these rare yeast infections, with the intent of providing practical assistance in clinical decision making. Because there is less clinical experience of patients with rare yeast infections and studies on these patients were not randomised, nor were groups compared, most recommendations are not robust in their validation but represent insights by use of expert opinions and in-vitro susceptibility results. In this Review, we report the key features of the epidemiology, diagnosis, antifungal susceptibility, and treatment outcomes of patients with Geotrichum, Saprochaete, Magnusiomyces, and Trichosporon spp infections.

A global view on fungal infections in humans and animals: opportunistic infections and microsporidioses

After cardiovascular diseases, infectious diseases are the second most common cause of death worldwide. Although these infections are caused mainly by viruses or bacteria, a systematically growing prevalence of human and animal opportunistic fungal infections is noticeable worldwide. More attention is being paid to this problem, especially due to the growing frequency of recalcitrant and recurrent mycoses. The latter are classically divided into superficial, which are the most common type, subcutaneous, and systemic. This work discusses opportunistic fungal pathogens without proven horizontal transmission between different animal species including humans and microsporidia as spore-forming unicellular parasites related to fungi; however, with a yet undetermined taxonomic position. The review also mentions aetiological agents, risk factors, epidemiology, geographical distribution, and finally symptoms characteristic for individual disease entities. This paper provides insight into fungal infections from a global perspective and simultaneously draws attention to emerging pathogens, whose prevalence is continuously increasing. Finally, this work also takes into consideration the correct nomenclature of fungal disease entities and the importance of secondary metabolites in the pathogenesis of fungal infections.

In vitro Antifungal Susceptibility Profiles of Cryptococcus neoformans var. grubii and Cryptococcus gattii Clinical Isolates in Guangxi, Southern China

This study analyzed the in vitro drug sensitivity of Cryptococcus spp. from Guangxi, Southern China. One hundred three strains of Cryptococcus were recovered from 86 patients; 14 were HIV positive and 72 were HIV negative. Ninety-two strains were identified as Cryptococcus neoformans var. grubii, while 11 strains were identified as Cryptococcus gattii (5 C. gattii sensu stricto and 6 Cryptococcus deuterogattii). The recovered strains were tested against commonly used antifungal drugs (fluconazole, amphotericin B, 5-fluorocytosine, itraconazole, and voriconazole) and to novel antifungal drugs (posaconazole and isavuconazole) using CLSI M27-A4 method. The results showed that all isolates were susceptible to most antifungal drugs, of which the minimum inhibitory concentration (MIC) ranges were as follows: 0.05-4 μg/ml for fluconazole, 0.25-1 μg/ml for amphotericin B; 0.0625-2 μg/ml for 5-fluorocytosine, 0.0625-0.25 μg/ml for itraconazole, 0.0078-0.25 μg/ml for voriconazole, 0.0313-0.5 μg/ml for posaconazole, 0.0020-0.125 μg/ml for isavuconazole for C. neoformans var. grubii isolates, and 1-16 μg/ml for fluconazole, 0.125-1 μg/ml for 5-fluorocytosine, 0.25-1 μg/ml for amphotericin B, 0.0625-0.25 μg/ml for itraconazole, 0.0156-0.125 μg/ml for voriconazole, 0.0156-0.25 μg/ml for posaconazole, and 0.0078-0.125 μg/ml for isavuconazole for C. gattii isolates. Furthermore, some C. neoformans var. grubii isolates were found to be susceptible-dose dependent to 5-fluorocytosine and itraconazole. In addition, a reduction in the potency of fluconazole against C. gattii is possible. We observed no statistical differences in susceptibility of C. neoformans var. grubii and C. gattii in the tested strains. Continuous observation of antifungal susceptibility of Cryptococcus isolates is recommended to monitor the emergence of resistant strains.

Comprehensive Analysis and Risk Identification of Pulmonary Cryptococcosis in Non-HIV Patients

Pulmonary cryptococcosis in the non-human immunodeficiency virus-infected population is uncommon. We aimed to explore the relevance between clinical presentations, radiological findings, and comorbidities and identify the outcome predictors. A total of 321 patients at Taichung Veterans General Hospital between 2005 and 2019 were included; of them, 204 (63.6%) had at least one comorbidity, while 67 (20.9%) had two or more. The most common comorbidities were diabetes mellitus (27.4%), malignant solid tumor (19.6%), autoimmune disease (15.6%), and chronic kidney disease (8.4%). Patients experiencing comorbidity, particularly those with multiple comorbidities, had a higher multilobar and extrapulmonary involvement, which could explain these patients being more symptomatic. In the overall population, extrapulmonary involvement independently predicted disease recurrence and death. Amongst patients with isolated pulmonary cryptococcosis, age, cryptococcal antigen (CrAg) titer in blood, and comorbidities not only predicted the extent of disease, but also its outcome. Of note, patients simultaneously with age ≥ 65 years, CrAg test ≥ 1:128, and multiple comorbidities had the lowest disease control of antifungal treatment (76.9%) and the highest rate of disease recurrence or death from any cause (40.0%). In conclusion, approximately two-thirds of patients had at least one underlying comorbidity. In addition to extrapulmonary involvement, old age, high CrAg titer in blood, and multiple comorbidities could act as risk factors for predicting the extent of disease and outcome.

Antifungal susceptibility testing with YeastONE™ is not predictive of clinical outcomes of Cryptococcus neoformans var. grubii fungemia

Mortality rates due to Cryptococcus neoformans var. grubii fungemia remain significant despite treatment with antifungal drugs. The predictive function of antifungal susceptibility and its correlation with treatment outcome remains controversial. A retrospective study was conducted from January 1, 2009, to December 31, 2016, on 85 patients with C. neoformans var. grubii fungemia confirmed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Antifungal drug susceptibility was determined using the YeastONE™ colorimetric broth microdilution method coupled with Vizion™ System following the Clinical and Laboratory Standards Institute guidelines. Six antifungal agents-amphotericin B, fluconazole, flucytosine, itraconazole, posaconazole, and voriconazole-were tested. The patients' demographic data and clinical information were abstracted for further analyses. Antifungal regimens consisting of amphotericin B with or without fluconazole or flucytosine were administered for induction treatment of these patients, followed with intravenous or oral fluconazole for maintenance therapy. Clinical outcomes were defined by 14- and 30-day mortality rates. Risk factors associated with outcomes were fitted in a logistic regression model by univariate or multivariate method. Eighty-five patients with C. neoformans var. grubii fungemia were enrolled in the study. The Sequential Organ Failure Assessment Score, Glasgow Coma Scale, Charlson comorbidity score, and adequate duration of therapy for amphotericin B were predictors for mortality in univariate analysis. Antifungal susceptibility testing with YeastONE™ does not predict clinical outcomes of C. neoformans var. grubii fungemia. Greater disease severity, high comorbidities, poor consciousness level, and inappropriate treatment were associated with increased mortality in cryptococcemia cases.

LAY ABSTRACT

Cryptococcus neoformans is an encapsulated yeast living in both plants and animals that is composed of three main serotypes: C. neoformans var. grubii, C. neoformans var. gattii, and C. neoformans var. neoformans. C. neoformans var. grubii is the most common disease-causing Cryptococcus species worldwide. C. neoformans var. gattii is more prevalent than C. neoformans var. neoformans in both tropical and subtropical regions of Asia. C. neoformans causes severe, even fatal, diseases such as pulmonary infection, bloodstream infection, skin and soft tissue infection, bone and joint infection, central nervous system infection, and disseminated infection, regardless of host immunocompetence. We conducted a retrospective study on 85 patients who contracted cryptococcemia from January 1, 2009, to December 31, 2016. This work conducted both microbiological and clinical studies involving in vitro susceptibility testing, demographic data, comorbidities, treatment modalities, and treatment outcomes. We utilized a modern medical technique-based instrument, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS; Biotyper, Bruker Daltonics, Inc.), which determines the unique proteomic fingerprint of an organism, to identify the C. neoformans serotype. We utilized Thermo Fisher Scientific™ Sensititre™ YeastONE™ colorimetric broth microdilution plates coupled with a Vizion™ Digital MIC Viewing System (a computer-assisted optical reading machine) to determine the in vitro susceptibility of amphotericin B, flucytosine, fluconazole, itraconazole, posaconazole, and voriconazole against 85 C. neoformans var. grubii blood isolates. In conclusion, the susceptibility patterns of these antifungal agents did not correlate significantly with treatment outcomes. However, a lower disease severity score, a lower Glasgow Coma Scale score, fewer comorbidities, and adequate amphotericin B treatment duration were predictors for treatment success in univariate analysis.

The Potential Role of Clinical Metagenomics in Infectious Diseases: Therapeutic Perspectives

Clinical metagenomics (CMg) is the process of sequencing nucleic acid of clinical samples to obtain clinically relevant information such as the identification of microorganisms and their susceptibility to antimicrobials. Over the last decades, sequencing and bioinformatic solutions supporting CMg have much evolved and an increasing number of case reports and series covering various infectious diseases have been published. Metagenomics is a new approach to infectious disease diagnosis that is currently being developed and is certainly one of the most promising for the coming years. However, most CMg studies are retrospective, and few address the potential impact CMg could have on patient management, including initiation, adaptation, or cessation of antimicrobials. In this narrative review, we have discussed the potential role of CMg in bacteriology, virology, mycology, and parasitology. Several reports and case-series confirm that CMg is an innovative tool with which one can (i) identify more microorganisms than with conventional methods in a single test, (ii) obtain results within hours, and (iii) tailor the antimicrobial regimen of patients. However, the cost-efficiency of CMg and its real impact on patient management are still to be determined.

Successful Treatment of Cryptococcal Meningitis and Cryptococcoma with Isavuconazole in a Patient Living with HIV

We describe the successful use of isavuconazole for treatment of an HIV-positive patient with cryptococcal meningitis following induction therapy with liposomal amphotericin B and flucytosine. Because the Cryptococcus neoformans isolate from cerebrospinal fluid had a borderline minimum inhibitory concentration of 8 mg/L, initial consolidation therapy was given with a daily dose of fluconazole 1200 mg based on area under the curve to minimum inhibitory concentration modelling data. Toxicity, and the radiological emergence of a cryptococcoma in the setting of immune reconstitution inflammatory syndrome, prompted a therapeutic switch to isavuconazole. Subsequent imaging after 19 weeks of isavuconazole shows a significant reduction in cryptococcoma size from 11 mm to complete resolution. The patient remains well after 210 days of therapy with a view to completion of treatment after 1 year.

Implication of efflux pumps and ERG11 genes in resistance of clinical Trichosporon asahii isolates to fluconazole

Introduction. Trichosporon asahii has been recognized as an opportunistic agent having a limited sensitivity to antifungal treatment.Hypothesis/Gap Statement. Molecular mechanisms of azole resistance have been rarely reported for Trichosproron asahii. Similar to other fungi, we hypothesized that both ERG11 gene mutation and efflux pumps genes hyper-expression were implicated.Aim. The current work aimed to study the sensitivity of clinical T. asahii isolates to different antifungal agents and to explore their resistance mechanisms by molecular methods including real-time PCR and gene sequencing.Methods. The sensitivity of T. asahii isolates to fluconazole, amphotericin B and voriconazole was estimated by the Etest method. Real-time PCR was used to measure the relative expression of Pdr11, Mdr and ERG11 genes via the ACT1 housekeeping gene. Three pairs of primers were also chosen to sequence the ERG11 gene. This exploration was followed by statistical study including the receiver operating characteristic (ROC) curve analysis to identify a relationship between gene mean expression and the sensitivity of isolates.Results. In 31 clinical isolates, the resistance frequencies were 87, 16.1 and 3.2 %, respectively, for amphotericin B, fluconazole and voriconazole. Quantitative real-time PCR demonstrated that only Mdr over-expression was significantly associated with FCZ resistance confirmed by univariate statistical study and the ROC curve analysis (P <0.05). The ERG11 sequencing revealed two mutations H380G and S381A in TN325U11 (MIC FCZ=8 µg ml^-1) and H437R in TN114U09 (MIC FCZ=256 µg ml^-1) in highly conserved regions (close to the haem-binding domain) but their involvement in the resistance mechanism has not yet been assigned.Conclusion. T. asahii FCZ resistance mechanisms are proven to be much more complex and gene alteration sequence and/or expression can be involved. Only Mdr gene over-expression was significantly associated with FCZ resistance and no good correlation was observed between FCZ and VCZ MIC values and relative gene expression. ERG11 sequence alteration seems to play a major role in T. asahii FCZ resistance mechanism but their involvement needs further confirmation.

Biotechnological applications of the non-conventional yeast Meyerozyma guilliermondii

Unconventional yeasts have attracted increased attentions owning to their unique biochemical properties and potential application in the biotechnological process. With the rapid development of microbial isolation tools and synthetic biology, more promising industrial yeasts have been isolated and characterized. Meyerozyma guilliermondii (anamorph Candida guilliermondii) is an ascomycetous yeast with several unique characteristics and physiology, such as the wide substrates spectrum and capability of various chemicals synthesis. The potential physiological and metabolic capabilities of M. guilliermondii, which can utilize various carbon sources including typical hydrophilic and hydrophobic materials were first reviewed in this review. Moreover, the wide applications of M. guilliermondii, such as for industrial enzymes production, metabolites synthesis and biocontrol were also reviewed. With the development of system and synthetic biology, M. guilliermondii will provide new opportunities for potential applications in biotechnology sectors in the future.

Clinical analysis in immunocompetent and immunocompromised patients with pulmonary cryptococcosis in western China

Cryptococcosis is a systemic infection and it may occur in immunocompromised and immunocompetent hosts. In order to better understand the clinical characteristics of patients with PC in different immune status, we retrospectively investigated the clinical, radiological, and treatment profiles of immunocompetent and immunocompromised patients with PC during a 10-year period (2008–2017). As a result, out of 136 patients, 94 (69.1%) were immunocompromised hosts. For the PC patients without CNS involvement, higher percentage of immunocompetent patients (39.5%, 15/38) had asymptomatic presentation than immunocompromised patients (6.3%, 3/48) (P < 0.05). Multiple pulmonary nodules (72.7%, 56/77), ground-glass attenuation/interstitial changes (94.4%, 17/18) and cavitation (88.6%, 31/35) were significantly frequent in immunocompromised patients (P < 0.05). A total of 47 patients were misdiagnosed as tuberculosis or tumors based on CT signs. PC was likely to be misdiagnosed as tuberculosis in immunocompromised patients (88.2%, 15/17), and tumor was more likely to be considered in immunocompetent patients (43.3%, 13/30). Immunocompetent patients accounted for 80% (24/30) of patients with definite diagnosis on surgical lung biopsy. Fluconazole monotherapy can achieve good clinical outcome in most PC patients without central nervous system (CNS) involvement (91.5%, 54/59). After 3 months of treatment, 92.7% (38/41) patients have improved imaging findings. In conclusion, PC has diverse imaging manifestations and it is easily misdiagnosed. Lobectomy should be carefully selected in immunocompetent patients with a single lung lesion. Fluconazole monotherapy is preferred for PC patients without CNS involvement.

Phenolic composition and biological activities of geographically different type of propolis and black cottonwood resins against oral streptococci, vaginal microbiota and phytopathogenic Fusarium species

AIMS

A multidisciplinary approach was used to compare phenolic composition, radical scavenging and antimicrobial activity of propolis samples from different geographical localities, and plant resin against various microorganisms.

METHODS AND RESULTS

Using UHPLC-qqqMS quantitative analysis, 28 phenolic compounds were determined. Caffeic and p-coumaric acids were identified as main phenolic acids in poplar propolis samples, except samples from Russia (P6) and China (P7). Radical scavenging activity (applying DPPH spectrophotometric assay) showed the highest activity of Serbian (40·51%) and Chinese (53·21%) propolis samples. Broth microdilution method was used for the oral cavity, fungal phytopathogenic and human vaginal isolates which have been identified at a molecular level. The most sensitive bacterial isolates were Lactobacillus acidophilus (MIC of 0·03-0·13 mg ml^-1 ) and the oral streptococci isolates (MIC values of 0·19-0·13 mg ml^-1 ). The most sensitive fungal phytopathogenic isolate was Fusarium oxysporum (MIC 0·003 mg ml^-1 ). All samples, except propolis from Serbia (P4) and Turkey (P5), showed a strong antifungal activity against Fusarium sporotrichioides, Fusarium subglutinans and Fusarium proliferatum.

CONCLUSION

The results of various tests indicate good radical scavenging and antimicrobial activity against important human and plant pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

A detailed propolis analysis is important when proposing a preparation of new biological antimicrobial products which have a positive impact on human health and reduce antibacterial resistance.

MIC distributions for amphotericin B, fluconazole, itraconazole, voriconazole, flucytosine and anidulafungin and 35 uncommon pathogenic yeast species from the UK determined using the CLSI broth microdilution method

Background

Epidemiological cut-off values and clinical interpretive breakpoints have been developed for a number of antifungal agents with the most common Candida species that account for the majority of infections due to pathogenic yeasts species. However, less-common species, for which susceptibility data are limited, are increasingly reported in high-risk patients and breakthrough infections.

Methods

The UK National Mycology Reference Laboratory performs routine antifungal susceptibility testing of clinical yeast isolates submitted from across the UK. Between 2002 and 2016, &gt;32 000 isolates representing 94 different yeast species were referred to the laboratory. Here we present antifungal susceptibility profiles generated over this period for amphotericin B, fluconazole, voriconazole, itraconazole, anidulafungin and flucytosine against 35 species of uncommon yeast using CLSI methodologies. MIC data were interpreted against epidemiological cut-off values and clinical breakpoints developed with Candida albicans, in order to identify species with unusually skewed MIC distributions that potentially indicate resistance.

Results

Potential resistance to at least one antifungal agent (&gt;10% of isolates with MICs greater than the epidemiological cut-off or clinical breakpoint) was evidenced for 29/35 species examined here. Four species exhibited elevated MICs with all of the triazole antifungal drugs against which they were tested, and 21 species exhibited antifungal resistance to agents from at least two different classes of antifungal agent.

Conclusions

This study highlights a number of yeast species with unusual MIC distributions and provides data to aid clinicians in deciding which antifungal regimens may be appropriate when confronted with infections with rarer yeasts.

Necessity to identify candida species accurately with minimum inhibitory concentration determination in each case of bloodstream infections

BACKGROUND

Bloodstream Candida infection is a life-threatening event among ICU admitted patients. This infection is caused by a diverse range of Candida species having varied minimum inhibitory concentrations.

OBJECTIVES

To identify Candida species causing bloodstream infections with their antifungal susceptibility determination.

METHODS

Candida species isolated from the blood of ICU admitted patients were identified by phenotypic as well as by molecular methods including PCR-RFLP using MspI restriction enzyme and MALDI TOF MS. The minimum inhibitory concentration of fluconazole, voriconazole, amphotericin B and caspofungin was determined against isolated Candida species by CLSI M27A₃ guidelines.

RESULTS

A total of 119 Candida species were isolated. Among them, C. tropicalis(n=29) was the predominant isolate followed by C. parapsilosis(n=18), C. glabrata (n=12), C. krusei (n=11) and C. albicans(n=11). Uncommon Candida species isolated were; Wickerhamomyces anomalus(n=15), Kodaemia ohmeri(n=8), C. lusitaniae (n=5) and C. auris (n=2). A varied antifungal MIC values were observed. Caspofungin had the lowest MIC among the tested antifungals. Increased fluconazole MIC was observed against the isolated Candida species including C. tropicalis. All the isolated C. lusitaniae and C. auris strains have ≥1mcg/ml amphotericin B MIC. In comparison to fluconazole, voriconazole was more effective when tested in vitro.

CONCLUSION

Emergence of uncommon Candida species having varied antifungal MIC warns the physicians to have a prompt, accurate identification with antifungal MIC determination in each case of bloodstream Candida infections.

Molecular identification and antifungal susceptibility testing of Pucciniomycotina red yeast clinical isolates from Rio de Janeiro, Brazil

Infections caused by Rhodotorula spp. are increasing worldwide. This study identified, through the light of the new taxonomic advances on the subphylum Pucciniomycotina, 16 isolates from blood cultures and compared their antifungal susceptibility on microdilution and gradient diffusion methods. Internal transcriber spacer sequencing identified Rhodotorula mucilaginosa (n = 12), Rhodotorula toruloides (n = 2), Rhodotorula dairenensis (n = 1), and Cystobasidium minutum (n = 1). Amphotericin B was the most effective drug. A good essential agreement was observed on MIC values of amphotericin B and voriconazole determined by the two methods. Therefore, the gradient method is useful for susceptibility tests of R. mucilaginosa against these drugs.

First Isolation, Antifungal Susceptibility, and Molecular Characterization of Cryptococcus neoformans from the Environment in Croatia

The purpose of this study was to investigate the presence of Cryptococcus neoformans species complex isolates from environmental sources in Croatia and to determine their molecular types and antifungal susceptibility. Swab samples of tree hollows and bird excreta in the soil beneath trees were collected. Samples included 472 (92.73%) samples obtained from tree hollows and 37 (7.27%) samples from bird excreta. Four C. neoformans species complex isolates were recovered from tree hollow swabs along the Mediterranean coast, while there were no isolates recovered from bird excreta or from the continental area. Three isolates were identified as molecular types VNI and one as VNIV. All tested antifungals showed high in vitro activity against the four isolates. This is the first report proving the presence of C. neoformans species complex in the environment of Croatia. The results of the study suggest a major risk of exposure for inhabitants living along the Croatian coast and that both VNI and VNIV molecular types can be expected in clinical cases of cryptococcosis. Susceptibility to antifungals confirmed that no resistance should be expected in patients with cryptococcosis at the present time.

Pulmonary cryptococcosis: A review of pathobiology and clinical aspects

Pulmonary cryptococcosis is an important opportunistic invasive mycosis in immunocompromised patients, but it is also increasingly seen in immunocompetent patients. The main human pathogens are Cryptococcus neoformans and C. gattii, which have a worldwide distribution. In contrast to cryptococcal meningitis, pulmonary cryptococcosis is still underdiagnosed because of limitations in diagnostic tools. It can mimic lung cancer, pulmonary tuberculosis, bacterial pneumonia, and other pulmonary mycoses both clinically and radiologically. Pulmonary nodules are the most common radiological feature, but these are not specific to pulmonary cryptococcosis. The sensitivity of culture of respiratory samples for Cryptococcus is poor and a positive result may also reflect colonisation. Cryptococcal antigen (CrAg) with lateral flow device is a fast and sensitive test and widely used on serum and cerebrospinal fluid, but sera from patients with pulmonary cryptococcosis are rarely positive in the absence of disseminated disease. Detection of CrAg from respiratory specimens might assist the diagnosis of pulmonary cryptococcosis but there are very few data. Molecular detection techniques such as multiplex reverse transcription polymerase chain reaction (RT-PCR) could also provide better sensitivity but these still require validation for respiratory specimens. The first line of treatment for pulmonary cryptococcosis is fluconazole, or amphotericin B and flucytosine for those with central nervous system involvement. Pulmonary cryptococcosis worsens the prognosis of cryptococcal meningitis. In this review, we summarize the biological aspects of Cryptococcus and provide an update on the diagnosis and management of pulmonary cryptococcosis.

Cell Envelope Integrity and Capsule Characterization of Rhodotorula mucilaginosa Strains from Clinical and Environmental Sources

Currently, there is very little known about the phenotypic variability within species of Rhodotorula strains and the role of their capsule. Cryptococcus neoformans has been considered the only encapsulated human fungal pathogen, but as more individuals come to live in states of immunocompromised health, they are more susceptible to fungal infections, including those by Rhodotorula. R. mucilaginosa species are some of those most commonly associated with clinical infections. We wanted to know if clinical and environmental strains of R. mucilaginosa demonstrated disparate capsule phenotypes. With limited antifungal options available and clinical Rhodotorula spp. often resistant to common antifungal drugs such as fluconazole, caspofungin (1, 2), and voriconazole (2), a better understanding of the fungal biology could inform the design and use of future antifungal drugs. The generation of an antibody specific to Rhodotorula fungi could be a useful diagnostic tool, and this work presents the first mention of such in the literature.

Rhodotorula yeasts are pink, encapsulated basidiomycetes isolated from a variety of environments and clinical settings. They are increasingly linked with disease, particularly central venous catheter infections and meningitis, in immunocompromised patients. Eight clinical and eight environmental strains molecularly typed as Rhodotorula mucilaginosa were compared to six Cryptococcus neoformans strains for phenotypic variability. Growth on cell integrity-challenging media suggested that R. mucilaginosa cells possess differences in signaling pathways, cell wall composition, or assembly and that their membranes are more susceptible to perturbations than those of C. neoformans. All 16 R. mucilaginosa strains produced urease, while none produced melanin with l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. India ink staining reveals that clinical R. mucilaginosa capsules are larger than environmental capsules but that both are generally smaller than C. neoformans capsules. All R. mucilaginosa strains were resistant to fluconazole. Only two clinical strains were susceptible to voriconazole; all of the environmental strains were resistant. We generated an anticapsular antibody (Rh1) to R. mucilaginosa; Rh1 did not bind C. neoformans control strains, was specific to Rhodotorula species, and bound to all tested Rhodotorula strains. Binding assays performed with wheat germ agglutinin (WGA), concanavalin A (ConA), calcofluor white (CFW), and eosin Y dye (EY) cell surface probes suggested that chitin may be more accessible in R. mucilaginosa but that the total abundance of chitooligomers is less than in C. neoformans. This report describes a novel reagent that can be used to identify Rhodotorula species and lays the foundation for future cell envelope composition analysis.

IMPORTANCE Currently, there is very little known about the phenotypic variability within species of Rhodotorula strains and the role of their capsule. Cryptococcus neoformans has been considered the only encapsulated human fungal pathogen, but as more individuals come to live in states of immunocompromised health, they are more susceptible to fungal infections, including those by Rhodotorula. R. mucilaginosa species are some of those most commonly associated with clinical infections. We wanted to know if clinical and environmental strains of R. mucilaginosa demonstrated disparate capsule phenotypes. With limited antifungal options available and clinical Rhodotorula spp. often resistant to common antifungal drugs such as fluconazole, caspofungin (1, 2), and voriconazole (2), a better understanding of the fungal biology could inform the design and use of future antifungal drugs. The generation of an antibody specific to Rhodotorula fungi could be a useful diagnostic tool, and this work presents the first mention of such in the literature.

Species distribution and antifungal susceptibility of 358 Trichosporon clinical isolates collected in 24 medical centres

OBJECTIVES

To provide species distribution and antifungal susceptibility profiles of 358 Trichosporon clinical isolates collected from 24 tertiary-care hospitals.

METHODS

Species identification was performed by sequencing the IGS1 region of rDNA. Antifungal susceptibility testing for amphotericin B, fluconazole, voriconazole and posaconazole followed the Clinical and Laboratory Standards Institute reference method. Tentative epidemiologic cutoff values (97.5% ECVs) of antifungals for Trichosporon asahii were also calculated.

RESULTS

Isolates were cultured mostly from urine (155/358, 43.3%) and blood (82/358, 23%) samples. Trichosporon asahii was the most common species (273/358, 76.3%), followed by T. inkin (35/358, 9.7%). Isolation of non-T. asahii species increased substantially over the last 11 years [11/77 (14.2%) from 1997 to 2007 vs. 74/281, (26.3%) from 2008 to 2018, p0.03]. Antifungal susceptibility testing showed high amphotericin B minimum inhibitory concentrations against Trichosporon isolates, with higher values for T. faecale. The ECV for amphotericin B and T. asahii was set at 4 μg/mL. Among the triazole derivatives, fluconazole was the least active drug. The ECVs for fluconazole and posaconazole against T. asahii were set at 8 and 0.5 μg/mL, respectively. Voriconazole showed the strongest in vitro activity against the Trichosporon isolates; its ECV for T. asahii was set at 0.25 μg/mL after 48 hours' incubation.

CONCLUSIONS

Trichosporon species diversity has increased over the years in human samples, and antifungal susceptibility profiles were species specific. Trichosporon asahii antifungal ECVs were proposed, which may be helpful to guide antifungal therapy.

Fluconazole resistance is not a predictor of poor outcome in patients with cryptococcosis

BACKGROUND

Cryptococcus isolates with high MICs to fluconazole are increasingly reported, and a potential clinical impact has been advocated. However, there are different methods to evaluate fluconazole MICs and comparative analysis among such techniques and their comprehensive correlation with clinical outcome are not available.

METHODS

Over a 13-year period (2000-2013), fluconazole MICs were determined for 62 cryptococcal isolates recovered from 22 patients with cryptococcosis using CLSI M27-A3, EUCAST, E test and Sensititre YeastOne, simultaneously. The relationship between the fluconazole MICs and the clinical outcome at week 10 was assessed in patients who received fluconazole as induction or maintenance therapy (n = 16).

RESULTS

The percentage of cryptococcal strains with MIC values ≥16 μg/mL according to different methods was CLSI 1.6%, EUCAST 16.1%, E test 31.6% and Sensititre YeastOne 53.2%. Among the 16 patients treated with fluconazole, no correlation between clinical outcome and any MIC value obtained with either method was observed. The only variable independently associated with a poor outcome was having a disseminated disease.

CONCLUSIONS

There is a weak correlation between fluconazole MICs against Cryptococcus spp. as determined by CLSI, EUCAST, E test and Sensititre YeastOne. Neither procedure could predict the clinical outcome of patients with cryptococcosis receiving fluconazole-based therapy. With present methods, fluconazole resistance in Cryptococcus may be clinically misleading.

Antifungal susceptibility of Saccharomyces cerevisiae and therapy in a murine model of disseminated infection

BACKGROUND

The incidence of systemic infections by Saccharomyces cerevisiae has increased in recent years, especially among immunocompromised patients. Amphotericin B, voriconazole or echinocandins have been used with favorable outcome against systemic infections by this fungus. However, clinical experience is limited and no in vivo studies have been conducted.

AIMS

We evaluated the in vitro activity of nine antifungal compounds against S.cerevisiae and the in vivo efficacy of those three antifungals showing the highest in vitro activity by using a murine model of systemic infection.

METHODS

Minimal inhibitory concentrations (MICs) were determined by the microdilution method against three strains of S. cerevisiae. After intravenous infection with 5×10⁷ CFUs, animals received liposomal amphotericin B (5mg/kg), voriconazole (25mg/kg) or anidulafungin (5mg/kg). Treatment efficacy was assessed by determining of CFUs/g in liver, kidney, brain, lung and spleen.

RESULTS

5-Fluorocytosine was the most in vitro active compound followed by amphotericin B, voriconazole and anidulafungin. The in vivo study showed that liposomal amphotericin B was the most effective drug driving highest fungal clearance.

CONCLUSIONS

All treatments reduced the fungal load in comparison to the control group, being liposomal amphotericin B the most effective drug followed by anidulafungin and finally voriconazole.

Novel multiplex real-time quantitative PCR detecting system approach for direct detection of Candida auris and its relatives in spiked serum samples

The multidrug-resistant opportunistic yeast species of Candida auris, Candida haemulonii, Candida duobushaemulonii and Candida pseudohaemulonii continue to endanger the healthcare settings around the globe. Due to the lack of a specific qPCR assay for detection of these species from clinical samples, we developed a multiplex qPCR assay. Analytical specificity and sensitivity showed 100% specificity and the sensitivity of up to ten genomes of target species with a high value of reproducibility (R² >0.99). Subsequently, from spiked serum samples, our qPCR specifically could detect up to ten genomes of C. auris and one genome of C. haemulonii, C. duobushaemulonii and C. pseudohaemulonii (R² >0.98). Lack of cross reaction with the human DNA, a high degree of specificity and sensitivity, showed the potential of our multiplex PCR for direct detection of C. auris and closely related species from serum samples of suspected patients. Future studies are warranted to assure its applicability in clinical settings.

In Vitro and In Vivo Assessment of FK506 Analogs as Novel Antifungal Drug Candidates

FK506 (tacrolimus) is an FDA-approved immunosuppressant indicated for the prevention of allograft rejections in patients undergoing organ transplants. In mammals, FK506 inhibits the calcineurin-nuclear factor of activated T cells (NFAT) pathway to prevent T-cell proliferation by forming a ternary complex with its binding protein, FKBP12, and calcineurin. FK506 also exerts antifungal activity by inhibiting calcineurin, which is essential for the virulence of human-pathogenic fungi. Nevertheless, FK506 cannot be used directly as an antifungal drug due to its immunosuppressive action. In this study, we analyzed the cytotoxicity, immunosuppressive activity, and antifungal activity of four FK506 analogs, 31-O-demethyl-FK506, 9-deoxo-FK506, 9-deoxo-31-O-demethyl-FK506, and 9-deoxo-prolyl-FK506, in comparison with that of FK506. The four FK506 analogs generally possessed lower cytotoxicity and immunosuppressive activity than FK506. The FK506 analogs, except for 9-deoxo-prolyl-FK506, had strong antifungal activity against Cryptococcus neoformans and Candida albicans, which are two major invasive pathogenic yeasts, due to the inhibition of the calcineurin pathway. Furthermore, the FK506 analogs, except for 9-deoxo-prolyl-FK506, had strong antifungal activity against the invasive filamentous fungus Aspergillus fumigatus Notably, 9-deoxo-31-O-demethyl-FK506 and 31-O-demethyl-FK506 exhibited robust synergistic antifungal activity with fluconazole, similar to FK506. Considering the antifungal efficacy, cytotoxicity, immunosuppressive activity, and synergistic effect with commercial antifungal drugs, we selected 9-deoxo-31-O-demethyl-FK506 for further evaluation of its in vivo antifungal efficacy in a murine model of systemic cryptococcosis. Although 9-deoxo-31-O-demethyl-FK506 alone was not sufficient to treat the cryptococcal infection, when it was used in combination with fluconazole, it significantly extended the survival of C. neoformans-infected mice, confirming the synergistic in vivo antifungal efficacy between these two agents.

The epidemiology of non-Candida yeast isolated from blood: The Asia Surveillance Study

Background

Current guidelines recommend echinocandins as first‐line therapy for candidemia. However, several non‐Candida yeast are non‐susceptible to echinocandins (echinocandin non‐susceptible yeast, ENSY), including Cryptococcus, Geotrichum, Malassezia, Pseudozyma, Rhodotorula, Saprochaete, Sporobolomyces and Trichosporon. In laboratories that are not equipped with rapid diagnostic tools, it often takes several days to identify yeast, and this may lead to inappropriate presumptive use of echinocandins in patients with ENSY fungemia. The aim of this study was to determine the distribution of ENSY species during a 1‐year, laboratory surveillance programme in Asia.

Methods

Non‐duplicate yeast isolated from blood or bone marrow cultures at 25 hospitals in China, Hong Kong, India, Singapore, Taiwan and Thailand were analysed. Isolates were considered to be duplicative if they were obtained within 7 days from the same patient.

Results

Of 2155 yeast isolates evaluated, 175 (8.1%) were non‐Candida yeast. The majority of non‐Candida yeast were ENSY (146/175, 83.4%). These included Cryptococcus (109 isolates), Trichosporon (23), Rhodotorula (10) and Malassezia (4). The proportion of ENSY isolates (146/2155, 6.7%) differed between tropical (India, Thailand and Singapore; 51/593, 8.6%) and non‐tropical countries/regions (China, Hong Kong and Taiwan; 95/1562, 6.1%, P = 0.038). ENSY was common in outpatient clinics (25.0%) and emergency departments (17.8%) but rare in intensive care units (4.7%) and in haematology‐oncology units (2.9%). Cryptococcus accounted for the majority of the non‐Candida species in emergency departments (21/24, 87.5%) and outpatient clinics (4/5, 80.0%).

Conclusions

Isolation of non‐Candida yeast from blood cultures was not rare, and the frequency varied among medical units and countries.

Five-year China Hospital Invasive Fungal Surveillance Net (CHIF-NET) study of invasive fungal infections caused by noncandidal yeasts: species distribution and azole susceptibility

Purpose

In this study, we report results from a 5-year surveillance for noncandidal yeast species causing invasive infections from 65 hospitals in China.

Materials and methods

Species identification was carried out by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) supplemented by rDNA sequencing, and fluconazole and voriconazole susceptibilities of yeasts were determined by Clinical and Laboratory Standards Institute (CLSI) disk diffusion methods.

Results

Overall, 884 noncandidal isolates belonging to 38 species were collected. Cryptococcus neoformans was the most common (75.6%), which also comprised 96.5% of the isolates from cerebrospinal fluid (CSF) and 62.6% from blood, followed by Trichosporon asahii (6.9%) and Rhodotorula mucilaginosa (5.1%). Fluconazole susceptibility and resistant rates were 74.1% and 9.7% for C. neoformans and 81.0% and 5.2% for T. asahii. Voriconazole exhibited good activity in comparison to these two species (99.5% and 98.3% of the isolates, were susceptible). However, 100% of the R. mucilaginosa isolates were resistant to both azoles. Other noncandidal yeast species showed reduced susceptibility to fluconazole (53.3%) but most were susceptible to voriconazole (94.3%). Over the 5 years, a decrease in the proportion of fluconazole-susceptible isolates was observed for C. neoformans (90%-67%, P<0.001) and other noncandidal yeast species (91%-66%, P<0.001). Moreover, the prevalence of azole-resistant R. mucilaginosa increased from 1% to 7% (P<0.001).

Conclusion

The shift in azole susceptibilities in mainland China calls for continued surveillance for noncandidal yeasts.

YEAST PANEL multiplex PCR for identification of clinically important yeast species: stepwise diagnostic strategy, useful for developing countries

Identification of opportunistic yeasts in developing countries is mainly performed by phenotypic assays, which are time-consuming and prone to errors. Wrong species identification may result in suboptimal treatment and inaccurate epidemiological data. To improve rapidity and accuracy of species identification, a diagnostic strategy using a stepwise "YEAST PANEL multiplex PCR assays" targeting 21 clinically important yeast species of Candida, Trichosporon, Rhodotorula, Cryptococcus, and Geotrichum was designed. Four hundred CBS reference strains were used for optimization and specificity testing. Eight hundred clinical species were prepared in blinded sets for multiplex polymerase chain reaction (PCR) and matrix-assisted laser desorption time of flight mass spectrophotometry (MALDI-TOF MS) investigation. Results obtained from YEAST PANEL multiplex PCR assay were 100% consistent with those of MALDI-TOF MS. Utilization of pure colony testing showed distinct amplicons for each species, thus eliminating the need for DNA extraction. The targeted yeast species of this assay are responsible for 95% of the yeast infections. In conclusion, due to the high accuracy and coverage of a broad range of yeasts, this assay could be useful for identification in routine laboratories and epidemiological studies.