Voriconazole Resistance Research Articles

Clinical Features and Outcomes of Invasive Fusariosis in Pediatric Patients with Acute Lymphoblastic Leukemia (ALL): A Case Series in a Single Tertiary Center in North-Eastern Mexico

Abstract Background Fusariosis is a pathology that is of great clinical concern in certain at-risk patient groups. Pediatric patients with ALL are in the greatest at-risk population as they are frequently in a post-chemotherapy state. The diagnosis for IFIs can be carried out by the criteria established in the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) and the notable intrinsic resistance of the Fusarium species to most of the antifungal agents available lead to high mortality rates in immunocompromised patients. Starting in 2002, the use of voriconazole was approved as empiric monotherapy as a first line therapy for the treatment of disseminated fusariosis. Other options are liposomal amphotericin B (LAB), Posaconazole or Isavuconazole. There are a few reports combined antifungal treatment in a pediatric population. In pediatric patients, the empirical and specific antifungal treatment is mostly inferred from clinical experience in adult patients. Methods We identified six patients with culture-proven fusariosis at a tertiary healthcare center in North-Eastern Mexico from May 2018- August 2021. We reported six cases of fusariosis categorized according to the EORTC/MSG. B cell ALL diagnosis was defined as a positive result in a B-cell leukemia panel. In terms of the descriptive statistics, continuous variables were reported as medians and [Interquartile range], while categorical variables were described via counts, frequencies, and (prevalence). Results The median age was 8 [6-12], 2 of the patients were female. All of the included patients were in the remission induction phase of their therapy and all patients had a confirmed B cell ALL and all patients presented with neutropenia. Four patients had a central venous catheter present, 3 of patients had a bacterial co-infection (E. coli, S. pneumoniae, Klebsiella blee). LAB was given as empirical therapy in 3 of patients while one patient received a combination of amphotericin B and voriconazole and the remaining patient received voriconazole monotherapy. Five patients had resistance to LAB, two patients showed voriconazole resistance. The definitive treatment was LAB plus Voriconazole in 5 (83.3%) patients. Five (83.3%) patients survived. Conclusions There are no clearly established guidelines for treatment options for fusariosis in pediatric patients. The majority of our reported patients presented with LAB-resistance and the combination of LAB with voriconazole has been used to control this pathology. There is still much more to explore and further research is needed into the indicated treatment plan and the susceptibility and therapeutic strategy for this specific population.

Comparative analysis of the biological characteristics and mechanisms of azole resistance of clinical Aspergillus fumigatus strains.

Aspergillus fumigatus is a common causative pathogen of aspergillosis. At present, triazole resistance of A. fumigatus poses an important challenge to human health globally. In this study, the biological characteristics and mechanisms of azole resistance of five A. fumigatus strains (AF1, AF2, AF4, AF5, and AF8) were explored. There were notable differences in the sporulation and biofilm formation abilities of the five test strains as compared to the standard strain AF293. The ability of strain AF1 to avoid phagocytosis by MH-S cells was significantly decreased as compared to strain AF293, while that of strains AF2, AF4, and AF5 were significantly increased. Fungal burden analysis with Galleria mellonella larvae revealed differences in pathogenicity among the five strains. Moreover, the broth microdilution and E-test assays confirmed that strains AF1 and AF2 were resistant to itraconazole and isaconazole, while strains AF4, AF5, and AF8 were resistant to voriconazole and isaconazole. Strains AF1 and AF2 carried the cyp51A mutations TR34/L98H/V242I/S297T/F495I combined with the hmg1 mutation S541G, whereas strains AF4 and AF8 carried the cyp51A mutation TR46/Y121F/V242I/T289A, while strain AF5 had no cyp51A mutation. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis revealed differences in the expression levels of genes associated with ergosterol synthesis and efflux pumps among the five strains. In addition, transcriptomics, RT-qPCR, and the NAD+/NADH ratio demonstrated that the mechanism of voriconazole resistance of strain AF5 was related to overexpression of genes associated with energy production and efflux pumps. These findings will help to further elucidate the triazole resistance mechanism in A. fumigatus.

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.

Azole-Containing Agar Plates and Antifungal Susceptibility Testing for the Detection of Azole-Resistant Aspergillus Species in Hospital Environmental Samples.

The indoor environment of hospitals should be considered as an important reservoir of azole resistant Aspergillus species. In this study, we evaluated azole-containing agar plates (ACAPs) and antifungal susceptibility testing (AFST) for the detection of azole-resistant Aspergillus species in hospital environmental samples. Between September 2021 and January 2022, environmental samples (108 instruments and 12 air) were collected from different wards of 4 educational hospitals in Mazandaran province, Iran. All samples were cultured using ACAPs. Recovered Aspergillus isolates were molecularly identified at species level using partial DNA sequencing of beta-tubulin gene. AFST of Aspergillus species was performed using the Clinical and Laboratory Standards Institute M38-A3 guideline. Screening for cyp51A mutations was also done. Overall, 18 (15.0%) isolates of Aspergillus species were recovered from ACAPs, of which Aspergillus tubingensis (50%) and Aspergillus fumigatus (38.9%) were the commonest species. No isolate of Aspergillus species grew on posaconazole (PCZ)-containing agar plates. Among the 18 Aspergillus isolated species from ACAPs, 83.3% were related to samples from instruments. Of the nine isolates of A. tubingensis, 22.2% and 44.4% isolates showed minimum inhibitory concentration (MIC) = 2 μg/mL against voriconazole (VCZ) and itraconazole, respectively; and 44.4% isolates showed MIC = 1 μg/mL against PCZ. Of the seven isolates of A. fumigatus, one (14.3%) was resistant to VCZ. This isolate showed F46Y, G54E, G138C, M172V, M220I, D255E, T289F, G432C, and G448S mutation in cyp51A. Our finding showed the emergence of high MICs in cryptic and non-fumigatus species of Aspergillus such as A. tubingensis and VCZ resistance in A. fumigatus in indoor environment of hospitals.

Diversity of Fungal Colonization in Respiratory Tract of Naïve Lung Cancer and The Emergence of Voriconazole Resistant Aspergillus

Fungal spores in the air can be inhaled and enter the human respiratory tract. The entry of fungi into the respiratory tract can cause colonization or infection depending on the host immune response. Fungal colonization is the first step into debilitating fungal disease in humans, especially in immunocompromised groups. The increased rate of drug-resistant fungi has been reported in human disease and the environment. This study aims to examine the diversity of fungal colonization in humans and the rate of fungal resistance to voriconazole. This cross-sectional study was done in patients with naïve lung cancer who had not been previously treated with any cancer therapy nor given antifungal agent. Induced sputum from 70 subjects was collected and inoculated in the Sabouraud Dextrose Agar medium. Macroscopic and microscopic examinations were performed to identify fungal species. Voriconazole susceptibility tests were done using the disc diffusion method. This study found Candida albicans, Aspergillus niger, Aspergillus fumigatus, and Penicillium sp. among the most common lower respiratory tract colonies. This study also found the colonization of up to 5 species in a single subject. A high rate of voriconazole-resistant Aspergillus sp. was found (42.4%) among 59 isolates tested. Given that these subjects had never taken antifungal agents previously, the high rate of voriconazole resistance might be attributed to the environment, such as community and agriculture. Mitigation of antifungal use in the agricultural sector, fungal diversity in the environment, and clinical study of fungal colonization/ infection in other high-risk groups are needed.

Biofilm Formation and Aspartyl Proteinase Activity and Their Association with Azole Resistance Among Candida albicans Causing Vulvovaginal Candidiasis, Egypt.

Candida albicans (C. albicans) is a major cause of vulvovaginal candidiasis (VVC), a condition that is commonly treated with azole agents. Biofilm formation and aspartyl proteinase production are important virulence factors that could be linked to azole resistance in C. albicans impeding therapy. To find out the association of both factors with azole resistance among C. albicans isolated from VVC cases in Egyptian nonpregnant women of childbearing age. In a cross-sectional study, C. albicans was isolated from nonpregnant females diagnosed clinically as having VVC during a 1-year study period. Susceptibility to azole agents was tested using the disc diffusion method. Biofilm formation and aspartyl proteinase production were assessed phenotypically. Additionally, two biofilm-related genes (ALS1 and HWP1) and three proteinase genes (SAP2, SAP4, and SAP6) were screened for using polymerase chain reaction (PCR). Among 204 C. albicans isolates, azole resistance ratios were as follows: voriconazole (30.4%), itraconazole (17.6%), fluconazole (11.3%) and econazole (6.4%). Biofilm-producing capacity was detected in 63.2% of isolates, and 63.2% were proteinase producers. The frequencies of ALS1 and HWP1 were 69.6% and 74.5%, respectively, while SAP2, SAP4, and SAP6 were 69.2%, 88.7%, and 64.7%, respectively. Biofilm formation was significantly associated with azole resistance (P < 0.001 for each tested azole agent) as was proteinase production (P < 0.001 for fluconazole, voriconazole, and econazole resistance and P = 0.047 for itraconazole). Among nonpregnant Egyptian women of childbearing age, azole resistance in C. albicans causing VVC is significantly associated with biofilm formation and proteinase production. The development of new therapeutic agents that can target these factors is warranted.

Clinical epidemiology of pulmonary aspergillosis in hospitalized patients and contribution of Cyp51A, Yap1, and Cdr1B mutations to voriconazole resistance in etiologic Aspergillus species.

Pulmonary aspergillosis is a life-threatening fungal infection with worldwide distribution. In the present study, clinical epidemiology of pulmonary aspergillosis and antifungal susceptibility of etiologic Aspergillus species were evaluated in one-hundred fifty patients with special focus on the frequency of voriconazole resistance. All the cases were confirmed by the clinical pictures, laboratory findings, and isolation of etiologic Aspergillus species which belonged to two major species, i.e., A. flavus and A. fumigatus. Seventeen isolates displayed voriconazole MIC greater than or equal to the epidemiological cutoff value. Expression of cyp51A, Cdr1B, and Yap1 genes was analyzed in voriconazole-intermediate/resistant isolates. In A. flavus, Cyp51A protein sequencing showed the substitutions T335A and D282E. In the Yap1 gene, A78C replacement led to Q26H amino acid substitution that was not reported previously in A. flavus resistant to voriconazole. No mutations associated with voriconazole resistance were found in the three genes of A. fumigatus. The expression of Yap1 was higher than that of two other genes in both A. flavus and A. fumigatus. Overall, voriconazole-resistant strains ofbothA. fumigatusand A. flavus demonstrated overexpression of Cdr1B, Cyp51A, and Yap1 genescompared tovoriconazole-susceptible strains.Although there are still ambiguous points about the mechanisms of azole resistance, our results showed that mutations were not present in majority of resistant and intermediate isolates, while all of these isolates showed overexpression in all three genes studied. As a conclusion, it seems that the main reasonof the emergence of mutation in voriconazole-resistant isolates of A. flavus and A. fumigatus is previous or prolonged exposure to azoles.

Afu-Emi1 Contributes to Stress Adaptation and Voriconazole Susceptibility in Aspergillus fumigatus.

Invasive aspergillosis (IA) is the second most common invasive fungal disease and is associated with high mortality rates. Aspergillus fumigatus is the predominant causal agent of this life-threatening infection. Triazoles are still the cornerstone of antifungal treatment, and voriconazole remains the first-line choice. However, voriconazole resistance has been increasingly reported, which results in significantly higher mortality rates for IA and is particularly problematic. In the present study, we report the identification and functional study of a protein with previously unknown function that is encoded by the gene designated Afu-emi1 (AFUA_1G07360). High-throughput gene replacement technology was applied to construct the knockout ΔAfu-emi1 strain and a revertant strain. The MICs for azoles, including posaconazole, itraconazole, and voriconazole, were evaluated via the broth microdilution method and E-tests, which revealed that disruption of Afu-emi1 resulted in 4-fold increased susceptibility to voriconazole. Colony growth in the presence of oxidants, namely, H2O2 and menadione, and osmotic pressure-altering agents, namely, NaCl and d-sorbitol, was measured. The Afu-emi1 mutant strain exhibited a significant growth defect under oxidative and osmotic stress. The reactive oxygen species (ROS) production levels with or without voriconazole pretreatment were determined, and the Afu-emi1 mutant strain exhibited significantly lower ROS production levels. The effects of Afu-emi1 disruption on voriconazole susceptibility, growth under stress, and ROS production were restored in the revertant strain. In addition, the expression of cyp51A, AfuMDR2, AfuMDR3, AfuMDR4, and cdr1b in the ΔAfu-emi1 strain was significantly reduced. In conclusion, deletion of the gene Afu-emi1 resulted in increased voriconazole susceptibility, attenuated ability for oxidative and osmotic stress adaptation, decreased ROS production, and downregulation of cyp51A, AfuMDR2, AfuMDR3, AfuMDR4, and cdr1b expression, suggesting that Afu-Emi1 is an important regulator of stress adaptation and cyp51A and efflux pump expression in this medically important fungus. IMPORTANCE Voriconazole is the first-line choice for IA, a life-threatening disease. Therefore, voriconazole resistance has become particularly problematic. Disruption of Afu-emi1 resulted in increased susceptibility to voriconazole, a significant growth defect under oxidative and osmotic stress, and downregulation of target enzyme Cyp51A and efflux pump expression, suggesting that Afu-Emi1 is an important regulator of stress adaptation and cyp51A and efflux pump expression in this medically important fungus. Targeting Afu-Emi1 might help to enhance azole therapeutic efficacy and impede azole resistance.

P001 Characteristics and dynamics of azole-resistant Aspergillus fumigatus variants emerging over a 28-year period in the Netherlands

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMBackground Aspergillus fumigatus, a globally distributed opportunistic pathogen, is the main cause of invasive aspergillosis, especially in immunocompromised patients with high mortality. The emergence of azole-resistant A. fumigatus isolates has been a significant concern worldwide and an important clinical problem.ObjectivesWe aim to determine the presence of variants in a large collection of clinical A. fumigatus isolates from the Netherlands, if the number of variants increased over time and if the presence of additional short nucleotide polymorphisms (SNPs) or tandem repeats (TR) variations impacted on the triazole phenotype.MethodsThe Radboud University Medical Center has collected 11 813 clinical A. fumigatus isolates since 1994. The collection includes isolates cultured from patients admitted to our own center, isolates sent from other hospitals for identification and in vitro susceptibility testing, and isolates sent from five university medical centers and five teaching hospitals that contribute to the national Aspergillus resistance surveillance. The genotypes were detected by Cyp51A Sanger sequencing. All isolates were subjected to in vitro susceptibility testing using the EUCAST microdilution reference method. Minimal inhibitory concentrations (MICs) were determined for itraconazole, voriconazole, posaconazole, in all isolates and for isavuconazole in isolates cultured in 2015 and thereafter.ResultsIn total, 1826 A. fumigatus isolates harbored azole-resistant mutations in the Cyp51A-gene with 92 genotypes. Tandem Repeat-associated resistance genotypes accounted for 55.43% of the variants and were involved in 1728 isolates (94.63%). TR34/L98H and TR46/Y121F/T289A resistance mutations remained dominant, and increasingly additional SNPs in the Cyp51A-gene or changes to the gene promoter were observed. The G448S mutation was relatively common and present in various genetic backgrounds. This SNP was most often found in isolates harboring the TR46 resistance mechanism (8 variants) and was also observed in two variants in the TR34 genetic background. TR34 and TR46 resistance mutations are associated with 1170 (64.07%) isolates that exhibited a pan-azole resistance phenotype, 547 (29.96%) a multi-azole resistance phenotype, and 75 (4.11%) resistance to a single azole. TR34/L98H confers high itraconazole resistance, while T289A confers high voriconazole resistance in the TR46 background. Isolates with a G448S point mutation show high MICs for both voriconazole and itraconazole. The TR34/L98H/T289A/G448S isolate showed low itraconazole MICs but high voriconazole resistance, and mutations in the promoter region, TR34/C-86 G/L98H, and (T-66 G)/TR34/L98H variants, showed increased voriconazole and isavuconazole MIC compared with the parent phenotype. TR46/Y121F/M172I/T289A/G448S variant was observed with an increased itraconazole (GM MIC 16 mg/L, 1→16 mg/l) and decreased voriconazole (GM MIC 18.664 mg/l, 4→16 mg/l) compared with the parent MIC of TR46/Y121F/T289A, while TR92/Y121F/M172I/T289A/G448S and TR46/Y121F/ T289A/G448S variants showed the consistent MIC distribution with parent genotype. The variants with more combination mutations showed pan-azole resistance with increased MIC distribution.ConclusionOur survey showed a significant increase in resistance genotypes in clinical A. fumigatus over a period of 28 years. Azoles resistance phenotypes vary from resistant variants in clinical isolates; it is an implication for clinical A. fumigatus infection treatment options and antifungal stewardship.

S9.2d Directed evolution of voriconazole resistance in Aspergillus fumigatus identifies novel mutations responsible for triazole resistance

S9.2 Azole resistance in Aspergillus fumiagatus: how hot is your hotspot?, September 23, 2022, 4:45 PM - 6:15 PM Aspergillus fumigatus is the leading invasive mold pathogens in humans. The first line of treatment for invasive A. fumigatus infections are the triazole antifungals that inhibit Erg11/Cyp51 lanosterol demethylase activity, blocking ergosterol biosynthesis. In recent years, triazole resistance of A. fumigatus has been increasingly reported, both as a result of widespread agricultural use of fungicidal triazoles and long-term treatment in patients with chronic aspergillosis. To date, the most common triazole resistance mechanisms in A. fumigatus are alterations in the erg11A/cyp51A gene or promoter, followed by overexpression of efflux pumps and mutations in hmg1, encoding HMG-CoA reductase. To identify novel triazole resistance mechanisms, we passaged A. fumigatus wild type and cyp51A-null strains under increasing concentrations of voriconazole (0.25 μg/ml-20 μg/ml) to generate resistant strains. Resistant isolates were whole-genome sequenced and compared with untreated controls. We identified known cyp51A and cyp51B mutations, and novel mutations in HMG1 and in previously uncharacterized genes in the ergosterol biosynthesis pathway as well as several efflux pumps. We identified at which stage of evolution each of the mutations occurred as well as their contribution to the resistance phenotype by re-introduction, alone and in combination, into the susceptible parental strain. Our study identified novel genes conferring triazole resistance and helps outline the complex stepwise evolutionary paths by which A. fumigatus develops resistance.

Species characterization and antifungal susceptibility profile of yeast isolates from blood cultures of fungemic patients in Thammasat University Hospital, Thailand

Background: Candida albicans is the most isolated fungal agent in a worldwide health system. Species distribution of Candida infection is different according to geographical regions. However, a shift in favor of non-albicans Candida species with antifungals resistance have increased as an important cause of candidemia. Objectives: This study aimed to identify the species of yeasts isolated from the blood samples of patients at the university hospital and to determine in vitro susceptibilities of three most common isolates against nine antifungal agents. Materials and methods:In total, 130 yeast isolates from 130 patients were defined the species using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Antifungal susceptibility testing was carried out using broth dilution Sensititre YeastOne panels included amphotericin B, 5-fucytosine, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, micafungin, and caspofungin. Results: The most common species in all age groups was C. tropicalis (n=48, 36.9%), followed by C. albicans (n=38, 29.2%). C. glabrata (n=23, 17.7%) was more common among elderly patients, while C. parapsilosis (n=9, 6.9%) was more frequently isolated from younger patients. Antifungal susceptibility testing in Candida species expressed MIC in the low level of almost antifungal drug except for reduced fluconazole susceptibility against C. glabrata and C. tropicalis isolates. Conclusion: C. tropicalis is the most common infection in candidemic patients. Fluconazole resistance strains were found in C. glabrata and C. tropicalis, respectively. In addition, voriconazole resistance strains were found in C. tropicalis.

Impact of COVID-19 on the antifungal susceptibility profiles of isolates collected in a global surveillance program that monitors invasive fungal infections.

Studies demonstrated the impact of the COVID-19 pandemic in the prevalence and susceptibility profiles of bacterial and fungal organisms. We analyzed 4821 invasive fungal isolates collected during 2018, 2019, and 2020 in 48 hospitals worldwide to evaluate the impact of this event in the occurrence and susceptibility rates of common fungal species. Isolates were tested using the CLSI broth microdilution method. While the percentage of total isolates that were C. glabrata (n = 710 isolates) or C. krusei (n = 112) slightly increased in 2020, the percentage for C. parapsilosis (n = 542), A. fumigatus (n = 416), and C. lusitaniae (n = 84) significantly decreased (P < .05). Fluconazole resistance in C. glabrata decreased from 5.8% in 2018–2019 to 2.0% in 2020, mainly due to fewer hospitals in the US having these isolates (5 vs. 1 hospital). Conversely, higher fluconazole-resistance rates were noted for C. parapsilosis (13.9 vs. 9.8%) and C. tropicalis (3.5 vs. 0.7%; P < .05) during 2020. Voriconazole resistance also increased for these species. Echinocandin resistance was unchanged among Candida spp. Voriconazole susceptibility rates in A. fumigatus were similar in these two periods (91.7% in 2018 and 2019 vs. 93.0% in 2020). Changes were also noticed in the organisms with smaller numbers of collected isolates. We observed variations in the occurrence of organisms submitted to a global surveillance and the susceptibility patterns for some organism-antifungal combinations. As the COVID-19 pandemic is still ongoing, the impact of this event must continue to be monitored to guide treatment of patients affected by bacterial and fungal infections.Lay SummarySecondary infections were documented in COVID-19 patients. We compared the prevalence of invasive fungal isolates consecutively collected in 48 worldwide hospitals and their susceptibility patterns between 2020, the year of the global COVID-19 pandemic, and the two prior years.

Differential Functions of Individual Transcription Factor Binding Sites in the Tandem Repeats Found in Clinically Relevant cyp51A Promoters in Aspergillus fumigatus.

ABSTRACTAspergillus fumigatus is the major filamentous fungal pathogen in humans. The gold standard treatment of A. fumigatus is based on azole drug use, but the appearance of azole-resistant isolates is increasing at an alarming rate. The cyp51A gene encodes the enzymatic target of azole drugs, and azole-resistant alleles of cyp51A often have an unusual genetic structure containing a duplication of a 34- or 46-bp region in the promoter causing enhanced gene transcription. These tandem repeats are called TR34 and TR46 and produce duplicated binding sites for the SrbA and AtrR transcription factors. Using site-directed mutagenesis, we demonstrate that both the SrbA (sterol response element [SRE]) and AtrR binding sites (AtrR response element [ATRE]) are required for normal cyp51A gene expression. Loss of either the SRE or ATRE from the distal 34-bp repeat of the TR34 promoter (further 5′ from the transcription start site) caused loss of expression of cyp51A and decreased voriconazole resistance. Surprisingly, loss of these same binding sites from the proximal 34- or 46-bp repeat led to increased cyp51A expression and voriconazole resistance. These data indicate that these duplicated regions in the cyp51A promoter function differently. Our findings suggest that the proximal 34- or 46-bp repeat in cyp51A recruits a corepressor that requires multiple factors to act while the distal repeat is free of this repression and provides the elevated cyp51A expression caused by these promoter duplications.

Fluconazole-resistant Candida parapsilosis clonally related genotypes: first report proving the presence of endemic isolates harbouring the Y132F ERG11 gene substitution in Spain

ObjectivesWe report here for the first time the presence of Candida parapsilosis isolates harbouring the Y132F ERG11 gene substitution in patients admitted to a Spanish hospital. MethodsWe studied the available (n = 104) C parapsilosis isolates from patients admitted to the Son Espases reference hospital in the Balearic Islands from 1 April 2019 to 30 November 2020. Isolates were sourced from 70 patients: catheter (n = 41), blood cultures (n = 37), lower respiratory tract (n = 15), intra-abdominal (n = 8), and other samples (n = 3). Isolates were genotyped and tested for antifungal susceptibilities to amphotericin B, triazoles, anidulafungin, and micafungin using EUCAST E.Def 7.3.2. The ERG11 gene was sequenced in fluconazole-resistant isolates. ResultsAmong the 104 isolates, fluconazole and voriconazole resistance was found in 87 (84%) and 30 (29%) isolates, respectively; all isolates were fully susceptible to echinocandins and amphotericin B. All fluconazole-resistant isolates harboured the Y132F substitution in the ERG11 gene and were grouped into 11 clonally related genotypes. A genotype accounted for 70% (61/87) of fluconazole-resistant isolates. Genotypes involving the fluconazole-resistant isolates were different from those found in the remaining fluconazole-susceptible genotypes. Fifty-six patients harboured fluconazole-resistant genotypes, and 35 of the 56 had candidaemia (48%), abdominal candidiasis (17%), or other forms of candidiasis (35%). Only 20% of the study patients infected by fluconazole-resistant genotypes had a history of azole use. DiscussionFluconazole resistance in C parapsilosis isolates from patients admitted to this reference hospital is not attributable to prior azole use, but rather to the presence of a group of fluconazole-resistant C parapsilosis genotypes that have become endemic.

Farklı Klinik Örneklerden İzole Edilen Candida Türlerinin Dağılımı ve Antifungal Duyarlılık Profilleri: 5 Yıllık Retrospoektif Analiz

Objective: In this study it was aimed to evaluate the distribution of Candida species and their antifungal susceptibility profiles in Kocaeli University Hospital, Kocaeli, Turkey. Methods: A retrospective study on the distribution of Candida species and antifungal susceptibility profile were conducted from January 2017 to December 2021 in our laboratory. Different clinical samples collected were cultured on Sabouraud dextrose agar and incubated for an appropriate time. Candida spp. were identification by MALDI-TOF MS. And their antifungal susceptibility profile were determined by the VITEK 2 Compact system (BioMérieux, France). Results: Totally 1667 clinical samples isolated from 1046 patients were included in this study. Of Clinical samples, 83.4% were from adults (≥ 18years) and 16.6% from pediatric group (&amp;lt; 18 years). Among all isolates, 1072 (64.3%) were C. albicans and 596 (35.7%) were non albicans Candida (NAC) species. C. albicans was mostly isolated from adults, whereas C. parapsilosis was mostly isolated from pediatric group. Regardless of Candida species identified, 88.7% were susceptible and 9.3% were resistant to fluconazole. The highest fluconazole resistance rate (25.4%) was observed in C. parapsilosis isolated from all departments. Voriconazole resistance ratio was 4.9%. The susceptibility rate of caspofungin and micafungin were 94.7% and 96%, respectively. The resistance rates of flucytosine and amphotericin B were 1.4% and 4.5%, respectively. Conclusion: In present study, the most common NAC species was determined as C. parapsilosis. The high prevalence and high fluconazole resistance of C. parapsilosis in our hospital may demonstrate that empirical fluconazole treatment is debatable.

Patterns of Antifungal Resistance in Adult Patients With Fungal Keratitis in South India

Antifungal resistance has been shown to impact treatment success, but research analyzing antifungal resistance is scarce. To evaluate changes in antifungal resistance over time. Ad hoc analysis of 3 randomized clinical trials including consecutive patients 18 years and older presenting with smear-positive fungal ulcers to Aravind Eye Hospitals in Madurai, Coimbatore, Pondicherry, and Tirunelveli in South India who participated in 1 of 3 clinical trials: the Mycotic Ulcer Treatment Trials (MUTT) I (2010 to 2011) or II (2010 to 2015) or the Cross-Linking Assisted Infection Reduction (CLAIR) trial (2016 to 2018). This post hoc analysis was designed in March 2021 and data were analyzed in May and November 2021. Minimum inhibitory concentration (MIC) of natamycin and voriconazole was determined from corneal cultures obtained using standardized methods outlined in the Clinical and Laboratory Standards Institute. The primary outcome of this post hoc analysis was MIC of natamycin and voriconazole. A total of 890 fungal isolates were obtained from 651 patients (mean [SD] age, 49.6 [13.0]; 191 [43.3%] female) from 2010 to 2018. MICs were available for 522 samples in 446 patients. Fungal isolates overall demonstrated a 1.02-fold increase per year in voriconazole resistance as measured by MICs (95% CI, 1.00-1.04; P = .06). In subgroup analyses, Fusarium species demonstrated a 1.04-fold increase in voriconazole resistance per year (95% CI, 1.00-1.06; P = .01). Fungal isolates showed a 1.06-fold increase in natamycin resistance per year overall (95% CI, 1.03-1.09; P < .001). Fusarium species had a 1.06-fold increase in natamycin resistance (95% CI, 1.05-1.08; P < .001), Aspergillus had a 1.09-fold increase in resistance (95% CI, 1.05-1.15; P < .001), and other filamentous fungi had a 1.07-fold increase in resistance to natamycin per year (95% CI, 1.04-1.10; P < .001). This post hoc analysis suggests that susceptibility to both natamycin and voriconazole may be decreasing over the last decade in South India. While a trend of increasing resistance could impact treatment of mycoses in general and infectious fungal keratitis in particular, further study is needed to confirm these findings and determine their generalizability to other regions of the world. ClinicalTrials.gov Identifiers: NCT00996736 and NCT02570321.

Epidemiology and Risk Factors of Candidemia Among Hospitalized Patients in a Turkish Tertiary Care Hospital.

Candidemia, which constitutes 50 - 70% of invasive Candida infections, is an important clinical condition with high mortality and difficulty in diagnosis and treatment. Our objective was to determine the epidemiology, risk factors of candidemia, the distribution, and antifungal susceptibilities of Candida spp. responsible for candidemia among hospitalized patients in Gazi University Medical Faculty Hospital. This was a laboratory-based, prospective observational study conducted between 2009 and 2010. The definition of nosocomial candidemia was based on CDC criteria. All relevant demographic and clinical data were collected from patient files. Candida spp. were identified by API ID32C system. Antifungal susceptibility testing was performed using broth microdilution method according to CLSI. Seventy-one candidemia episodes were identified with the incidence of 0.94 cases/1,000 hospital admissions. C. albicans was isolated in 47.9% of the admissions and in 52.1% of non-albicans Candida admissions. Among the latter, C. parapsilosis and C. tropicalis were the most frequent species. The most common risk factors were use of antibiotics (94.4%), hospitalization in the last 1 month (93%), history of hospitalization in ICU (74.6%), and CVC use (70.4%). Abdominal surgery, urethral catheter insertion, and use of piperacillin/tazobactam was found to increase the risk of C. albicans. A history of hospitalization within the last 3 months increased the risk of developing candidemia with non-albicans Candida spp. In total, fluconazole resistance was 20% (24.2% for C. albicans and 16.2% for non-albicans Candida strains) and voriconazole resistance was 5.7% (12.1% for C. albicans and 0% for non- albicans Candida). This study provided a relevant source of information for the prediction of high-risk patients and the implementation of prevention strategies for nosocomial candidemia.

Delineation of the Direct Contribution of Candida auris ERG11 Mutations to Clinical Triazole Resistance.

ABSTRACTResistance to fluconazole is one of clinical characteristics most frequently challenging the treatment of invasive Candida auris infections, and is observed among >90% of all characterized clinical isolates. In this work, the native C. auris ERG11 allele in a previously characterized fluconazole-susceptible clinical isolate was replaced with the ERG11 alleles from three highly fluconazole-resistant clinical isolates (MIC ≥256 mg/L), encoding the amino acid substitutions VF125AL, Y132F, and K143R, using Cas9-ribonucleoprotein (RNP) mediated transformation system. Reciprocally, the ERG11WT allele from the same fluconazole-susceptible clinical isolate, lacking any resistance-associated mutation, was introduced into a previously characterized fluconazole-resistant clinical isolate, replacing the native ERG11K143R allele, using the same methods. The resulting collection of strains was subjected to comprehensive triazole susceptibility testing, and the direct impact each of these clinically-derived ERG11 mutations on triazole MIC was determined. Introduction of each of the three mutant ERG11 alleles was observed to increase fluconazole and voriconazole MIC by 8- to 16-fold. The MIC for the other clinically available triazoles were not significantly impacted by any ERG11 mutation. In the fluconazole-resistant clinical isolate background, correction of the K143R encoding mutation led to a similar 16-fold decrease in fluconazole MIC, and 8-fold decrease in voriconazole MIC, while the MIC of other triazoles were minimally changed. Taken together, these findings demonstrate that mutations in C. auris ERG11 significantly contribute to fluconazole and voriconazole resistance, but alone cannot explain the substantially elevated MIC observed among clinical isolates of C. auris.IMPORTANCE Candida auris is an emerging multidrug-resistant and health care-associated pathogen of urgent clinical concern. The triazoles are the most widely prescribed antifungal agents worldwide and are commonly utilized for the treatment of invasive Candida infections. Greater than 90% of all C. auris clinical isolates are observed to be resistant to fluconazole, and nearly all fluconazole-resistant isolates of C. auris are found to have one of three mutations (encoding VF125AL, Y132F, or K143R) in the gene encoding the target of the triazoles, ERG11. However, the direct contribution of these mutations in ERG11 to fluconazole resistance and the impact these mutations may have the susceptibility of the other triazoles remains unknown. The present study seeks to address this knowledge gap and potentially inform the future application the triazole antifungals for the treatment of infections caused by C. auris.

The natural occurring Y129F polymorphism in Rhizopus oryzae (R. arrhizus) Cyp51Ap accounts for its intrinsic voriconazole resistance.

Rhizopus oryzae is intrinsically resistant to voriconazole, a commonly used antifungal agent. In this work, we analyze the role of two natural polymorphisms present in the target of azole drugs. We established that F129 residue is responsible of the intrinsic voriconazole resistance in this species.

Prevalence, epidemiology and clinical outcome of Candida auris infections: Experience from a tertiary care hospital in Jaipur.

Candida auris is identified as an emerging pathogen worldwide. It is multidrug resistant and causes invasive healthcare-associated infections. Our retrospective study was conducted to determine the prevalence and epidemiology of C. auris infections in a tertiary care hospital in Jaipur. 24 clinical C. auris strains were included, most being from urine. The majority patients needed intensive care and had at least one underlying co-morbid condition. A history of broad-spectrum antibiotic or antifungal usage was present in 85%. Fluconazole, voriconazole, amphotericin B and 5-fluorocytosine resistance was seen in 96, 42, 33 and 8% isolates respectively. No echinocandin resistance was noted.