Voriconazole Minimum Inhibitory Concentrations Research Articles

Isolate distribution and antifungal susceptibility of Saccharomyces cerevisiae in the national regional medical center of Southwest China for women and children during 2018–2023

BackgroundSaccharomyces cerevisiae has been considered a harmless yeast, but in recent years, increasing evidence has shown that it can cause disease in humans, especially invasive infections in infants/children and vulvovaginal infections in women. This study aimed to investigate the clinical information and antifungal susceptibility of clinical cases with S. cerevisiae and establish a foundation for the prevention and treatment of fungal infections.MethodsThis study was conducted from May 2018 to May 2023 at a national regional medical center in Southwest China for women and children. The demographic and clinical characteristics of patients isolated with S. cerevisiae were collected and analyzed. All the isolates were cultured on Sabouraud medium plates and identified by MALDI-TOF MS. The antifungal susceptibility of S. cerevisiae to 10 agents (amphotericin B, fluconazole, itraconazole, voriconazole, micafungin, caspofungin, terbinafine and 5-flucytosine) was determined via the microdilution broth method to determine the minimum inhibitory concentrations (MICs).ResultsA total of 75 cases of S. cerevisiae isolated from patients with vulvovaginal candidiasis (VVC, 44 cases), pneumonia (13 cases), or diarrhea (18 cases) were included after data review. The MICs of voriconazole and flucytosine for S. cerevisiae isolated from different body sites differed, with higher resistance in intestinal isolates. In this study, S. cerevisiae caused VVC, but there was no clear evidence that it was involved in pneumonia or diarrhea. Compared with those of Candida albicans, the primary pathogen of VVC, the MICs of fluconazole (11.96 ± 5.78 µg/mL vs. 67.64 ± 16.62 µg/mL, p = 0.002), itraconazole (0.77 ± 0.19 µg/mL vs. 2.31 ± 0.53 µg/mL, p = 0.008), voriconazole (0.22 ± 0.09 µg/mL vs. 5.02 ± 1.09 µg/mL, p < 0.001), and terbinafine (10.41 ± 0.84 µg/mL vs. 14.93 ± 4.77 µg/mL, p < 0.001) for S. cerevisiae (isolated from the genital tract) were significantly lower, while those of micafungin (0.14 ± 0.01 µg/mL vs. 0.06 ± 0.01 µg/mL, p < 0.001) and caspofungin (0.27 ± 0.04 µg/mL vs. 0.06 ± 0.01 µg/mL, p < 0.001) were significantly greater.ConclusionAzoles remain the recommended regimen for S. cerevisiae-related VVC, and the use of amphotericin B vaginal effervescent tablets could be considered for the treatment of azole-resistant isolates. The antifungal susceptibility of S. cerevisiae varies according to the isolated source, and the pathogenicity trend of S. cerevisiae should be studied.

Association between in vitro susceptibility and clinical outcomes in fungal keratitis

PurposeThe purpose of this study was to assess the association between antifungal susceptibility as measured by minimum inhibitory concentration (MIC) and clinical outcomes in fungal keratitis.MethodsThis pre-specified secondary analysis of the Mycotic Ulcer Treatment Trial II (MUTT II) involved patients with filamentous fungal keratitis presenting to Aravind Eye Hospitals in South India. Antifungal susceptibility testing for natamycin and voriconazole was performed on all samples with positive fungal culture results according to Clinical and Laboratory Standards Institute Guidelines. The relationship between MIC and clinical outcomes of best-corrected visual acuity, infiltrate or scar size, corneal perforation, need for therapeutic penetrating keratoplasty, and time to re-epithelialization were assessed.ResultsWe obtained MIC values from 141 patients with fungal keratitis. The most commonly cultured organisms were Aspergillus (46.81%, n = 66) and Fusarium (44.68%, n = 63) species. Overall, there was no association between antifungal MICs and clinical outcomes. Subgroup analysis revealed that among Fusarium-positive cases, higher voriconazole MIC was correlated with worse three-month best-corrected visual acuity (p = 0.03), increased need for therapeutic penetrating keratoplasty (p = 0.04), and time to re-epithelialization (p = 0.03). No significant correlations were found among Aspergillus-positive cases. There were no significant correlations found between natamycin MIC and clinical outcomes among organism subgroups.ConclusionsDecreased susceptibility to voriconazole was associated with increased odds of requiring a therapeutic penetrating keratoplasty in Fusarium-positive cases. Susceptibility to natamycin was not associated with any of the measured outcomes.

Genetic diversity and antifungal susceptibilities of environmental Cryptococcus neoformans and Cryptococcus gattii species complexes

Cryptococcosis is an opportunistic systemic mycosis caused by Cryptococcus neoformans and C. gattii species complexes and is of increasing global importance. Maintaining continued surveillance of the antifungal susceptibility of environmental C. neoformans and C. gattii isolates is desirable for better managing cryptococcosis by identifying resistant isolates and revealing the emergence of intrinsically resistant species. Relevant research data from Egypt are scarce. Thus, this study aimed to report the genetic diversity of C. neoformans and C. gattii species complexes originating from different environmental sources in Egypt, antifungal susceptibility profiles, antifungal combinations, and correlations of susceptibility with genotypes. A total of 400 environmental samples were collected, 220 from birds and 180 from trees. Cryptococcus spp. were found in 58 (14.5%) of the samples, 44 (75.9%) of the isolates were recovered from birds and 14 (24.1%) from trees. These isolates were genotyped using M13 polymerase chain reaction-fingerprinting and URA5 gene restriction fragment length polymorphism analysis. Of the 31 C. neoformans isolates, 24 (77.4%), 6 (19.4%) and one (4.4%) belonged to VNI, VNII, and VNIII genotypes, respectively. The 27 C. gattii isolates belonged to VGI (70.4%), VGII (18.5%), and VGIII (11.1%) genotypes. Non-wild type C. neoformans and C. gattii isolates that may have acquired resistance to azoles, amphotericin B (AMB), and terbinafine (TRB) were observed. C. gattii VGIII was less susceptible to fluconazole (FCZ) and itraconazole (ITZ) than VGI and VGII. C. neoformans isolates showed higher minimum inhibitory concentrations (MICs) to FCZ, ITZ, and voriconazole (VRZ) than those of C. gattii VGI and VGII. Significant (P < 0.001) correlations were found between the MICs of VRZ and ITZ (r = 0.64) in both C. neoformans and C. gattii isolates, FCZ and TRB in C. neoformans isolates, and FCZ and TRB (r = 0.52) in C. gattii isolates.There is no significant differences in the MICs of TRB in combination with FCZ (P = 0.064) or in combination with AMB (P = 0.543) and that of TRB alone against C. gattii genotypes. By calculating the fractional inhibitory concentration (FIC) index, the combination of FCZ + AMB was synergistic against all tested genotypes. These findings expand our knowledge of ecological niches, genetic diversity, and resistance traits of C. neoformans and C. gattii genotypes in Egypt. Further investigations into how they are related to clinical isolates in the region are warranted.

Genome-wide analysis of in vivo-evolved Candida auris reveals multidrug-resistance mechanisms.

Candida auris, an emerging and multidrug-resistant fungal pathogen, has led to numerous outbreaks in China. While the resistance mechanisms against azole and amphotericin B have been studied, the development of drug resistance in this pathogen remains poorly understood, particularly in invivo-generated drug-resistant strains. This study employed pathogen whole-genome sequencing to investigate the epidemiology and drug-resistance mutations of C. auris using 16 strains isolated from two patients. Identification was conducted through Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibilities were assessed using broth microdilution and Sensititre YeastOne YO10. Whole-genome sequencing revealed that all isolates belonged to the South Asian lineage, displaying genetic heterogeneity. Despite low genetic variability among patient isolates, notable mutations were identified, including Y132F in ERG11 and A585S in TAC1b, likely linked to increased fluconazole resistance. Strains from patient B also carried F214L in TAC1b, resulting in a consistent voriconazole minimum inhibitory concentration of 4µg/mL across all isolates. Furthermore, a novel frameshift mutation in the SNG1 gene was observed in amphotericin B-resistant isolates compared to susceptible ones. Our findings suggest the potential transmission of C. auris and emphasize the need to explore variations related to antifungal resistance. This involves analyzing genomic mutations and karyotypes, especially in vivo, to compare sensitive and resistant strains. Further monitoring and validation efforts are crucial for a comprehensive understanding of the mechanisms of drug resistance in C. auris.

Alarming Increase of Azole-Resistant Candida Causing Blood Stream Infections in Oncology Patients in Egypt

Candidemia is a life-threatening invasive fungal infection in immunocompromised patients. The widespread use of azoles and the shift toward non-albicans Candida (NAC) species remarkably increase azole resistance in developing countries. We aimed to study candidemia trends and associated risk factors in oncology patients since they vary geographically, and rapid and appropriate treatment improves outcomes. Vitek 2 was used to identify the Candida species, and the E-test determined their susceptibility to azoles. Candida was the cause of 3.1% (n = 53/1701) of bloodstream infections (BSIs) during a 1-year study. Candida tropicalis was the most predominant species among the 30 candidemia episodes studied (36.7%), followed by C. albicans (33.3%). However, C. krusei, C. guilliermondii, C. pelliculosa, C. parapsilosis, C. famata, and C. inconspicua accounted for 30.0% of the isolates. An increased risk of NAC BSI was significantly associated with chemotherapy and leucopenia (P = 0.036 and 0.016, respectively). However, the multivariable analysis revealed that leucopenia was the only independent risk factor (P = 0.048). Fluconazole and voriconazole resistance were 58.3% and 16.7%, with NAC species showing higher resistance rates than C. albicans. Both fluconazole and voriconazole minimum inhibitory concentration (MIC) median values were higher in NAC than in C. albicans, but only voriconazole was significantly higher (0.220 versus 0.048 μg/ml, P = 0.047). In conclusion, the increased prevalence of NAC BSIs and incredibly high fluconazole resistance rates in cancer patients emphasize the necessity of antifungal stewardship to preserve voriconazole effectiveness, continued surveillance of candidemia, and future studies into azole resistance molecular mechanisms.

Effect of the 1064 nm Nd: YAG Laser on the MICs of Antifungals Used in Clinical Practice for the Treatment of Fungal Nail Infections.

Introduction: The fungal nail infection (onychomycosis) involves 18%-40% of all nail disorders, which, although not fatal, can cause mechanical, aesthetic, occupational, and economic problems. Drug treatments due to prolonged treatment periods, drug interactions, adverse effects, and slow progression may associate with numerous negative outcomes. This study aimed to evaluate the long-pulsed 1064-nm Nd: YAG laser effect on fungal colonies and subsequently possible change in the minimum inhibitory concentrations (MICs) of common antifungals compared with the same non-lasered colonies as a novel way to investigate laser and antifungal interaction. Methods: Sixty onychomycosis samples consisting of saprophyte (n=20), dermatophyte (n=20), and yeast (n=20) duplicate colonies were isolated. A series was treated by a long-pulsed 1064-nm Nd: YAG laser. Afterward, the MIC (CLSI-M38-A2 and CLSI-M27-A3) of two series against common antifungals were compared. Results: After 1064-nm Nd: YAG laser irradiation in all 20 tested saprophytes, the MICs of terbinafine (P value<0.035) were changed, and in all 20 tested dermatophytes, the MICs of voriconazole (P value<0.021) were changed. Also, in all 20 tested yeasts, the MICs of caspofungin (P value<0.037) were changed. Moreover, in saprophytes, dermatophytes, and yeasts, significant changes in the MICs of itraconazole (P value<0.032), terbinafine (P value<0.025), and caspofungin (P value<0.037) were detected. Our result showed the GM MICs of the 1064-nm Nd: YAG laser in all saprophyte, dermatophyte, and yeast groups were lower than in the control group. Conclusion: The present study indicated that the long-pulsed 1064-nm Nd: YAG laser significantly changes the MICs of antifungals in onychomycosis clinical samples.

Spectrum and functional properties of &lt;i&gt;ERG11&lt;/i&gt; gene mutations in fluconazole-resistant &lt;i&gt;Candida albicans&lt;/i&gt; strains isolated from HIV-infected patients

Rationale. The low efficacy of azole antimycotics in treatment of Candida infections, especially in HIV-infected patients, is often associated with overexpression of the ERG11 gene in Candida spp., which results in increased production of ergosterol the target of the above antimycotic drugs. Researchers have found ERG11 gene mutations that can modify its overexpression effects by increasing or decreasing it. However, the findings reported by different laboratories and countries are highly contradictory.&#x0D; The purpose of the study is to explore the spectrum and functional properties of ERG11 gene mutations in fluconazole-resistant Candida albicans strains isolated from HIV-infected patients.&#x0D; Materials and methods. The study was performed using 10 C. albicans strains inherently resistant to fluconazole and voriconazole and isolated from the oropharynx of HIV-infected patients; the strains were provided from the collection of the Gabrichevsky Moscow Research Institute of Epidemiology and Microbiology. The strains were assessed by their sensitivity to antimycotic agents: anidulafungin, micafungin, caspofungin, posaconazole, voriconazole, itraconazole, fluconazole, amphotericin B, 5-flucytosine. Expression levels of the ERG11 gene were measured by quantitative PCR. ERG11 gene mutations were identified by Sanger sequencing.&#x0D; Results. Five mutations (E266D, G464S, I471L, D116E, and V488I) were detected in the ERG11 gene in seven C. albicans strains; six strains carried non-associated co-occurring mutations. Increased expression of the ERG11 gene was found in six C. albicans strains. The V488I mutation demonstrated a strong negative association with the increased expression of the ERG11 gene (r = 0.845; p 0.05). The minimum inhibitory concentration (MIC) in strains carrying mutations was a hundred times as low (p 0.05) as MIC in strains without mutations. In mutation carriers, posaconazole and itraconazole MICs were on average 16.5 times as low as MICs of voriconazole and fluconazole (p 0.001). The presence of mutations in the ERG11 gene had almost no effect on MICs of the tested antimycotics of the echinocandin, polyene, and pyrimidine groups.&#x0D; Conclusion. Multiple mutations were detected in the ERG11 gene in most of the C. albicans strains isolated from HIV-infected patients and resistant to fluconazole and voriconazole. Except for the V488I mutation, the detected mutations were not associated with the overexpression of the ERG11 gene and decreased the effects of overexpression of the ERG11 gene by up to 100 times, though they did not eliminate the inherent resistance to triazole antimycotics.

Clinical manifestations and susceptibility of Scedosporium/Lomentospora infections at a tertiary medical centre in Taiwan from 2014 to 2021: A retrospective cohort study.

Scedosporiosis/lomentosporiosis is a globally emerging and crucial fungal infection. However, clinical data on Scedosporium/Lomentospora infections in Taiwan are scarce. This study aimed to explore the clinical characteristics of Scedosporium/Lomentospora-infected patients and evaluate the susceptibility of these isolates to antifungal agents. The clinical features of Scedosporium/Lomentospora-infected patients at a tertiary teaching hospital in Northern Taiwan between 2014 and 2021 were retrospectively reviewed; isolates from these patients were identified to species level for antifungal susceptibility testing. Among 44 patients, 27 (61.4%) had scedosporiosis/lomentosporiosis, whereas 17 (38.6%) were colonised with Scedosporium/Lomentospora species. Scedosporium apiospermum was the main coloniser; scedosporiosis was primarily caused by S. boydii. Trauma history, steroid and immunosuppressant use were the most common risk factors for developing these infections. Among 27 patients with scedosporiosis/lomentosporiosis, one was lost to follow-up and seven (7/26, 26.9%) died. Most patients with S. apiospermum infection have a history of trauma, leading to cutaneous, bone and ocular infections. Pulmonary, sinus and disseminated infections and mortality were frequently reported in patients with S. boydii infection. Voriconazole's minimum inhibitory concentration was low for S. boydii, S. apiospermum and S. aurantiacum. Caspofungin, micafungin and anidulafungin were active against S. boydii and S. apiospermum. A potentially novel Scedosporium species was identified in this study, with distinct clinical manifestations and antifungal susceptibility. At our centre, S. boydii is the main causative species of scedosporiosis; voriconazole could be the first-line treatment in Taiwan. Our study supports the importance of speciation, rather than only categorising these isolates into S. apiospermum species complex.

Elucidating the clinical, microbiological and molecular diagnostic aspects of Macrophomina phaseolina keratitis.

This study reports the clinico-microbiological features of Macrophomina phaseolina keratitis. Clinically diagnosed as microbial keratitis, six patients underwent microbiological evaluation. Fungal culture isolates from cornea were subjected to DNA sequencing of the ITS region, phylogenetic analysis and reconfirmation by polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) of six antifungal drugs were determined by microbroth dilution method against the six isolates. All patients were treated with antifungals. Failed medical therapy necessitated therapeutic penetrating keratoplasty (TPK). Corneal buttons were processed for histopathology. In all patients, the corneal scraping showed septate hyaline fungal filaments. The BLAST analysis for ITS sequences of all six fungal isolates suggested M. phaseolina, however, when limited to sequences from type material, they matched M. pseudophaseolina. Phylogenetic analysis could not differentiate between these two species and clustered in a single clade. PCR assay of specific gene sequence [MpCal (calmodulin)] reconfirmed all isolates as M. phaseolina. The MICs of voriconazole and posaconazole were lowest (0.03 to 2 and 0.1 to 2µg/mL respectively) and all isolates were susceptible to natamycin. Except for case 1, which healed with a scar on treatment, all other cases worsened, despite medical treatment, necessitating TPK. Histopathology of 3 out of 4 buttons showed the presence of fungal filaments. While direct microscopic examination of corneal scrapings is helpful in diagnosis, identification of M. phaseolina in culture is challenging. Although MICs of commonly used antifungals are low response to medical therapy is not encouraging; patients may require TPK for resolution of infection in M. phaseolina keratitis.

&lt;em&gt;Scedosporium&lt;/em&gt; species and &lt;em&gt;Lomentospora&lt;/em&gt; prolificans in Italian cystic fibrosis patients: prevalence and distribution in seven centers using a selective medium

Background and aims. Scedosporium species and Lomentospora prolificans are the filamentous fungi isolated more frequently from the cystic fibrosis (CF) lower airways, after Aspergillus fumigatus. Previous studies showed that, in CF patients, Scedosporium species and Lomentospora prolificans are responsible for airways colonization/ infection, enhancing pulmonary deterioration, and for severe invasive infections in CF patients undergoing lung transplantation. Aims of our project were to evaluate the prevalence of Scedosporium and Lomentospora species in Italian patients with CF, and to evaluate the interest of the Scedosporium-selective colture medium SceSel compared to routinely used agar-based culture media, in order to improve laboratory diagnostic performances.Materials and methods. A total of 1977 sputum samples from 1154 CF patients were collected and processed according to CF Italian recommendations in the year 2017 (January 1st to December 31st). The SceSel agar was used in addition to the routine culture procedures to burst growth and isolation of Scedosporium/ Lomentospora species. The fungal isolates were identified by classical mycological methods and polymerase chain reaction-based DNA sequencing of ITS1 and ITS4 regions. Susceptibility of the isolates to antifungal drugs was investigated by E-test method. Results. Among the 1154 enrolled patients, 62 (5.3%) were positive for Scedosporium/Lomentospora species (median age: 27y; range 8-64y; 33 male). Out of 1977 samples, 93 were positive for Scedosporium/Lomentospora species, and 13 (13.9%) were recovered only on SceSel agar. According to molecular analyses, isolation rates of each species were: S. apiospermum 53.1%, S. boydii 37.5%, L. prolificans 6.3% and S. aurantiacum 3.1%. Amphotericin B minimum inhibitory concentration (MIC) values were above or equal to 2 mg/L in all strains. Voriconazole MIC values were below or equal to 0.38 mg/L in almost all strains, proving this drug to be the most effective antimycotic for members of Scedosporium species. Otherwise, Lomentospora prolificans showed to be resistant to all considered antifungal drugs, only Voriconazole seems to be active on some Lomentospora prolificans isolates. Conclusions. Our results suggest that SceSel agar should be used in combination with routine media as standard microbiological protocol and procedures are not always adequate to isolate Scedosporium and Lomentospora species in CF respiratory samples. Molecular identification and susceptibility tests are needed, especially for strains isolated from critical patients and those considered for transplantation, as they might develop invasive scedosporiosis.

Exophiala lecanii-corni keratitis presenting as a serpiginous pigmented superficial lesion: a case report

Rationale:Patients with bullous keratopathy (BK) treated by Descemet stripping automated endothelial keratoplasty (DSAEK) have a compromised cornea, due to the administration of topical steroid, postsurgical use of contact lenses, and impaired barrier function of the corneal epithelium by BK. We report a case of Exophiala lecanii-corni (E lecanii-corni) keratitis presenting as a serpiginous pigmented superficial lesion after DSAEK.Patient concerns:An 81-year-old woman who had undergone cataract surgeries, suffered from decreased vision in the left eye. She was diagnosed BK and she underwent DSAEK. Two months after DSAEK, a pigmented superficial lesion developed on the left cornea. The lesion migrated and recurred repeatedly and she was referred to our department. Best corrected vision was 20/220.Diagnoses:Light microscopy of a corneal scraping revealed branching fungal hyphae. Fungal culture showed growth of a black colony, identified as E lecanii-corni by ribosomal DNA sequencing.Interventions:We started topical treatment with 1% voriconazole and 1.5% levofloxacin. Antifungal susceptibility testing showed that the minimum inhibitory concentration of voriconazole was 0.06 μg/mL.Outcomes:The lesion scarred after treatment for 3 months, and left best corrected vision improved to 20/40.Lessons:Genus Exophiala is known as 1 of the “black molds” and a cause of chromomycosis. This is the first description of E lecanii-corni keratitis, and pigmented corneal epithelial lesions may be characteristic of this fungal genus.

A 23 bp cyp51A Promoter Deletion Associated With Voriconazole Resistance in Clinical and Environmental Isolates of Neocosmospora keratoplastica.

In the fungal pathogen Aspergillus fumigatus, resistance to azole antifungals is often linked to mutations in CYP51A, a gene that encodes the azole antifungal drug target lanosterol 14α-demethylase. The aim of this study was to investigate whether similar changes could be associated with azole resistance in a Malaysian Fusarium solani species complex (FSSC) isolate collection. Most (11 of 15) clinical FSSC isolates were Neocosmospora keratoplastica and the majority (6 of 10) of environmental isolates were Neocosmospora suttoniana strains. All 25 FSSC isolates had high minimum inhibitory concentrations (MICs) for itraconazole and posaconazole, low MICs for amphotericin B, and various (1 to >32 mg/l) voriconazole susceptibilities. There was a tight association between a 23 bp CYP51A promoter deletion and high (>32 mg/l) voriconazole MICs; of 19 FSSC strains sequenced, nine isolates had voriconazole MICs > 32 mg/l, and they all contained the 23 bp CYP51A promoter deletion, although it was absent in the ten remaining isolates with low (≤12 mg/l) voriconazole MICs. Surprisingly, this association between voriconazole resistance and the 23 bp CYP51A promoter deletion held true across species boundaries. It was randomly distributed within and across species boundaries and both types of FSSC isolates were found among environmental and clinical isolates. Three randomly selected N. keratoplastica isolates with low (≤8 mg/l) voriconazole MICs had significantly lower (1.3–7.5 times) CYP51A mRNA expression levels than three randomly selected N. keratoplastica isolates with high (>32 mg/l) voriconazole MICs. CYP51A expression levels, however, were equally strongly induced (~6,500-fold) by voriconazole in two representative strains reaching levels, after 80 min of induction, that were comparable to those of CYP51B. Our results suggest that FSSC isolates with high voriconazole MICs have a 23 bp CYP51A promoter deletion that provides a potentially useful marker for voriconazole resistance in FSSC isolates. Early detection of possible voriconazole resistance is critical for choosing the correct treatment option for patients with invasive fusariosis.

Invasive Aspergillosis by Aspergillus flavus: Epidemiology, Diagnosis, Antifungal Resistance, and Management.

Aspergillus flavus is the second most common etiological agent of invasive aspergillosis (IA) after A. fumigatus. However, most literature describes IA in relation to A. fumigatus or together with other Aspergillus species. Certain differences exist in IA caused by A. flavus and A. fumigatus and studies on A. flavus infections are increasing. Hence, we performed a comprehensive updated review on IA due to A. flavus. A. flavus is the cause of a broad spectrum of human diseases predominantly in Asia, the Middle East, and Africa possibly due to its ability to survive better in hot and arid climatic conditions compared to other Aspergillus spp. Worldwide, ~10% of cases of bronchopulmonary aspergillosis are caused by A. flavus. Outbreaks have usually been associated with construction activities as invasive pulmonary aspergillosis in immunocompromised patients and cutaneous, subcutaneous, and mucosal forms in immunocompetent individuals. Multilocus microsatellite typing is well standardized to differentiate A. flavus isolates into different clades. A. flavus is intrinsically resistant to polyenes. In contrast to A. fumigatus, triazole resistance infrequently occurs in A. flavus and is associated with mutations in the cyp51C gene. Overexpression of efflux pumps in non-wildtype strains lacking mutations in the cyp51 gene can also lead to high voriconazole minimum inhibitory concentrations. Voriconazole remains the drug of choice for treatment, and amphotericin B should be avoided. Primary therapy with echinocandins is not the first choice but the combination with voriconazole or as monotherapy may be used when the azoles and amphotericin B are contraindicated.

Outbreak of Candida auris in Spain: A comparison of antifungal activity by three methods with published data

Candida auris is an emerging pathogen causing candidaemia outbreaks in several countries for which azole, amphotericin B (AmB) and echinocandin resistance has been reported. In this study, the antifungal susceptibilities of 73 Spanish C. auris isolates (56 bloodstream and 17 urine) to eight antifungal agents were determined using three methods. Isolates were identified by internal transcribed spacer (ITS) sequencing, and minimum inhibitory concentrations (MICs) of fluconazole, isavuconazole, itraconazole, posaconazole, voriconazole, anidulafungin, micafungin and AmB were determined by EUCAST methodology and Sensititre® YeastOne® (SYO) (bloodstream isolates) and Liofilchem® MIC Test Strip (all isolates). Agreement between the methods was analysed and the MICs (ours and published data) were categorised using recently proposed epidemiological cut-off values (ECVs). Fluconazole MICs were >64 mg/L, whilst >60% of voriconazole MICs were >1 mg/L by the three methods. Posaconazole was the most active azole (EUCAST geometric mean MIC, 0.053 mg/L), followed by isavuconazole (0.066 mg/L) and itraconazole (0.157 mg/L). Echinocandins MICs were ≤0.5 mg/L by SYO and EUCAST. The overall lowest AmB MICs (≤0.25 mg/L) were obtained by EUCAST. Essential agreement (±2 dilutions) between EUCAST and SYO was >93% for the eight antifungals. For this new C. auris clade, all isolates were resistant to fluconazole, and MICs for anidulafungin, micafungin and AmB were ≤1 mg/L using dilution methods. Voriconazole MICs were method-dependent. The number of non-wild-type (non-WT) isolates depended on the ECV applied; by the 97.5% ECV all isolates were WT except for isavuconazole (1.8% non-WT). Good essential agreement (>93%) was observed between EUCAST and SYO.

Microsatellite Typing and Resistance Mechanism Analysis of Voriconazole-Resistant Aspergillus flavus Isolates in South Korean Hospitals.

A recent surveillance study in South Korea revealed that 14% (7/50) of Aspergillus flavus clinical isolates had a voriconazole minimum inhibitory concentration of ≥4 μg/ml. Of seven non-wild-type (non-WT) isolates, six ear isolates from four hospitals shared the same microsatellite genotype. None of the non-WT isolates showed cyp51 mutations associated with azole resistance. However, the mean expression levels of efflux pump (MDR2, atrF, and mfs1) and target (cyp51A) genes exhibited significant differences between non-WT and other isolates.

In vitro activity of four triazole antifungal drugs against clinically common and uncommon yeast species.

Background and Purpose:Incidence of fungal infections caused by opportunistic fungal pathogens, such as yeasts and yeast-like species, has undergone an increase in otherwise healthy individuals. These pathogens account for high mortality and show reduced susceptibility to the routine antifungal drugs. Accordingly, antifungal susceptibility testing is an urgent need in the determination of the susceptibility spectrum of antifungals and selection of appropriate antifungal agents for the management of patients with fungal infection.Materials and Methods:The present study was conducted on 110 yeast strains belonging to 15 species recovered from clinical specimens. Susceptibility of the isolates to four antifungal drugs (i.e., fluconazole, itraconazole, voriconazole, and posaconazole) was tested according to the Clinical and Laboratory Standards Institute guidelines M27-A3 and M27-S4.Results:Fluconazole exhibited no activity against 4.3% (n=2) of C. albicans isolates, whereas the remaining 44 isolates had a minimum inhibitory concentration (MIC) range of 0.125-4 μg/ml. Voriconazole had the lowest geometric mean MIC (0.03 µg/ml) against all isolated yeast species, followed by posaconazole (0.07 µg/ml), itraconazole (0.10 µg/ml), and fluconazole (0.60 µg/ml). Overall, all of the isolates had reduced voriconazole MICs with a MIC range of 0.016-0.5 μg/ml, except for one isolate of C. albicans that had a MIC of 1 μg/ml. Candida haemulonii as a multidrug-resistant fungus showed a fluconazole MIC of > 64 μg/ml.Conclusion:The current study provides insight into the antifungal susceptibility profiles of clinically common and uncommon yeast species to four triazole antifungal agents. According to our findings, voriconazole was the most active agent. Awareness about antifungal susceptibility patterns is highly helpful in the selection of appropriate antifungal drugs and identification of the efficiency of the currently used agents.

Correlation between antifungal resistance and virulence factors in Candida albicans recovered from vaginal specimens

Candida albicans is considered as the leading species causing vulvovaginal candidiasis. Numerous virulence determinants and escalating resistance to antifungal therapy have contributed to its pathogenicity. However, correlation between resistance profiles and virulence patterns of C. albicans is not very well-investigated, which was the main focus of the current study. C. albicans isolates (n = 65) were recovered from vaginal swab specimens and identified to the species level. Antifungal susceptibilities of isolates were performed against (amphotericin B, nystatin, clotrimazole, fluconazole, voriconazole, and micafungin), and their minimum inhibitory concentrations (MICs) were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Virulence patterns including secreted hydrolases (phospholipase, aspartyl protease, and haemolysin), cell surface hydrophobicity, and biofilm production were evaluated. Associations between resistance profiles and virulence patterns of tested C. albicans isolates were analyzed. Isolates showed variable levels of resistance and virulence patterns. Furthermore, there are significant (p < 0.05) positive correlations between amphotericin B MICs and biofilm production. However, significant (p < 0.05) negative correlations are found between fluconazole and voriconazole MICs and cell surface hydrophobicity as well as biofilm production. Moreover, significant (p < 0.05) negative correlations are detected between voriconazole MICs and aspartyl protease production. This study revealed significant correlations between resistance profiles and virulence patterns of C. albicans isolates recovered from vulvovaginal specimens.

Antifungal susceptibility of Aspergillus spp., Scedosporium spp. and Exophiala spp. isolated from patients with cystic fibrosis

Background: Moulds are frequently recovered from respiratory samples of cystic fibrosis (CF) patients. During the last decade, antifungal resistance in non-Candida species is increasingly reported. Azole resistance in Aspergillus fumigatus is a well-known problem and it was firstly reported in 1997 in three itraconazole-resistant clinical isolates. Since then, the main azole resistance mechanism reported are mutations at the CYP51A gene which encodes the azole drug target, the 14-α-sterol demethylase. The aims of this study were to overview the susceptibility profile from different fungal species isolated from respiratory secretions of Argentinean CF patients and to describe the molecular mechanisms of azole resistance in the isolated Aspergillus fumigatus strains. Methods & Materials: Amphotericin B, itraconazole, posaconazole and voriconazole minimum inhibitory concentrations (MICs) for 41 fungal strains: 34 Aspergillus spp. (22 A. fumigatus, 3 Aspergillus flavus, 2 Aspergillus niger, 6 Aspergillus terreus and 1 Aspergillus lentulus), 6 Scedosporium spp. (4 Scedosporium apiospermum and 2 Scedosporium auarnticum) and 1 Exophiala dermatitidis recovered from 20 CF patients were determined by using the CLSI M38-A2 document and Etest. The study of the azole mechanism of resistance in A. fumigatus, the full CYP51A coding sequences and its 5́UTR regions were amplified and sequenced. Results: For amphotericin B, MICs were above the epidemiological cut-off values (ECV) in 100% of A. lentulus, 100% of S. auranticum and 50% of S. apiospermum. For voriconazole, MICs were above the ECV in 4.5% of A. fumigatus, 16.7% of A. terreus and 100% of A. lentulus. For posaconazole, MICs were above the ECV in 13.6% of A. fumigatus and 100% A. lentulus. For itraconazole, MICs were above the ECV in 13.6% A. fumigatus, 100% A. lentulus, 75% S. apiospermum and 100% S. auranticum. Three A. fumigatus strains showing mutations in their CYP51A genes were isolated. Conclusion: Azole drugs are one of the few therapeutic options to treat invasive fungal infections. The emergence of resistance is a problem that should be continuously monitored specially in CF patients.

In vitro synergy of natamycin and voriconazole against clinical isolates of Fusarium, Candida, Aspergillus and Curvularia spp

AimTo determine the minimum inhibitory concentrations (MICs) of voriconazole and natamycin, alone and in combination, against the clinical isolates of Fungus and to evaluate the synergy between the drugs in...

Screening of antifungal susceptibility in cave-dwelling aspergilli and report of an amphotericin B-resistant Aspergillus flavus

Caves are stable environments that favour the development of several microorganisms. The aspergilli represent a large number of species isolated from caves including strains capable of causing serious invasive opportunistic infections in humans. Considering that caves may harbour resistant strains to many antibiotics, investigation on the response of opportunistic aspergilli, isolated from pristine and tourist caves to antifungal agents and the mechanisms involved in resistance might be clinically relevant. A total of 32 strains of the species Aspergillus candidus, A. flavus, A. fumigatus, A. niger, A. tamarii, and A. terreus were isolated from caves in the iron quadrangle in Brazil. The strains were tested for their susceptibility to amphotericin B (AMB), itraconazole, voriconazole and terbinafine. One strain was analysed for the mechanism involved in the AMB-resistance, i.e., ergosterol content, lipid peroxidation and enzymatic activity of the antioxidant system. Terbinafine minimum inhibitory concentrations (MICs) ranged between 0.003 and 1.0 µg/mL; voriconazole MICs ranged between 2.0 and >16.0 µg/mL; itraconazole MICs ranged between 0.25 and 8.0 µg/mL and amphotericin B MICs ranged between 0.03 and 4.0 µg/mL. The AMB-resistant strain of A. flavus was detected with MIC value of 4 µg/mL. Resistance to AMB relied on higher ergosterol levels and increased enzymatic activity of the peroxidase and superoxide-dismutase, with lower lipid peroxidation. These results enhance the knowledge of natural antifungal resistance in the subterranean ecosystem, and broaden the knowledge about the subterranean microbiota.