Fluconazole Minimum Inhibitory Concentrations Research Articles

SPECIES DISTRIBUTION AND ANTIFUNGAL SUSCEPTIBILITY OF VAGINAL <i>CANDIDA</i> ISOLATES

Introduction: Vulvovaginal candidiasis (VVC) is the most common Candida infection in females of reproductive age. Data concerning the species identification and antifungal susceptibility of vaginal Candida isolates are of great importance for the infection management. Aim: The aim of the present study was to determine the species distribution and antifungal susceptibility of Candida isolates obtained from vaginal samples of women with VVC. Material and methods: A total of 125 vaginal Candida isolates were collected and tested. The definitive species identification was performed by VITEC2 Compact (Bio Merieux, France) using YST ID cards. The minimum inhibitory concentrations (MICs) of nine antifungal agents were determined by the commercial system Micronaut-AM (Merlin Diagnostika GmbH, Germany). Results: Overall, 8 Candida species were established among the vaginal yeast isolates. The most common was C. albicans (77.6%), followed by C. glabrata (12%), C. krusei (4%), C. kefyr (2.4%), C. spherica (1.6%), C. lusitaniae, C. utilis, and C. sake (each one 0.8%). All C. albicans and 20 non-albicans Candida (NAC) were susceptible to nine antifungal agents. In the group of NAC, 8 isolates were resistant to fluconazole – 5 C. krusei with intrinsic resistance, 2 C. spherica, and 1 C. sake. The fluconazole MICs of C. spherica and C. sake were 32 - 128 μg/mL, and 16 μg/mL, respectively. Conclusions: C. albicans was the main causative agent of VVC. Among NAC, C. glabrata was the predominant species. In general, vaginal C. albicans and non-albicans Candida were susceptible to azoles as well as echinocandins, amphotericin B and 5-fluorocytosine. Of particular interest was the detection of rare non-albicans Candida isolates with acquired resistance to azoles.

Antimicrobial properties of Clausena anisata (Rutaceae) essential oil from Bafou area against the pathogenic fungus Candida albicans and antioxidant activity

The aim of the present work was to determine the antimicrobial and antioxidant activities of Clausena anisata essential oil. The extraction of essential oils was performed by the hydro distillation method with a Clevenger apparatus. The determination of essential oils chemical composition was conducted by gas chromatography and gas chromatography coupled with mass spectrometry. Then the antimicrobial activity was assessed using disk diffusion method and micro titration. In order to determine the antioxidant activity 2 methods were carried out: the free radical scavenging assay was performed using the DPPH+ radical (2,2-diphenyl-1-picrylhydrazyl) and the method with ABTS radical reagents (acid2, 2'-azynobis-[3-ethylbenzothiazoline-6 ​​sulfonic acid]). The yield of extraction of the essential oil was 0.77%. The study of its chemical composition revealed E- anethol (70.77%), methyl iso eugenol (13.85) as major compounds. The anti-radical DPPH test revealed a SC50 of 1g/L; 0.265g/L respectively for DPPH and ABTS tests. The results also highlighted a potent antimicrobial property. An antimicrobial screening study revealed a susceptibility of Candida albicans isolates at a concentration of 8000 ppm. This activity was characterized by minimum inhibitory concentrations of 2000 ppm for all the tested pathogenic yeasts Sab1, Sab2, Sab3, Sab250, Sab2501, Sab256, Sab259 and Sab290. The essential oil minimum inhibitory concentration (MIC) was lower than the MIC of fluconazole. The same observations were resulted with the fungicidal effect. These data can be used as a starting point for subsequent studies to produce antifungal and antioxidant drugs to face the challenge of the antimicrobial resistance and oxidative stress.

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.

Fluconazole-resistant Candida parapsilosis complex candidemia and analysis of mutations in the ERG11 gene from Pakistan.

Recent reports of the emergence of fluconazole resistance in Candida parapsilosis species complex poses a challenge, more specifically in settings where echinocandin-based treatment regime is not feasible. This study reported emergence of fluconazole resistance in C. parapsilosis species complex strains isolated from blood cultures. This retrospective observational study was conducted from 2018 to 2020 at a tertiary care laboratory from Pakistan. Fluconazole-resistant C. parapsilosis species complex fungemia cases were identified from laboratory database and clinical details were collected. Identification of C. parapsilosis species complex was done using API 20C AUX and Cornmeal Tween80 agar morphology. Minimum inhibitory concentrations (MICs) were determined using Sensititre YeastONE and interpretation was done with CLSI M60 ED1:2017. ERG11 gene region was amplified and sequenced by Sanger sequencing and analysed by MEGA 11 Software. A total of 13 (8.5%) fluconazole-resistant isolates were identified from 152 C. parapsilosis species complex candidemia cases. Fluconazole MICs of resistant isolates ranged between 8 and 256 μg/mL. Analysis of ERG11 gene revealed nonsynonymous mutations at position Y132F in 86% of the fluconazole-resistant isolates. Diabetes and hospitalization were important risk factors for candidemia with fluconazole-resistant C. parapsilosis complex. This is the first report of the emergence and molecular mechanisms of fluconazole resistance in C. parapsilosis species complex from Pakistan. Y132F mutation in the ERG11 gene was the most common mutation in fluconazole-resistant strains. These findings are concerning and necessitate better diagnostics, newer antifungals, ongoing surveillance and further insights on resistance mechanisms in the country.

Antifungal susceptibility of clinically isolated invasive Candida tropicalis in East China from 2017 to 2021

Objective: To explore the epidemiological characteristics of sample distribution and antifungal susceptibilities of clinically invasive C. tropicalis isolates from 2017 to 2021 in East China. Methods: Using a retrospective analysis, the East China Invasive Fungal Infection Group (ECIFIG) collected C. tropicalis clinically isolated from 32 hospitals in East China between January 2017 and December 2021. The identification results of the strains were reviewed using mass spectrometry by the central laboratory of the Shanghai East Hospital. The minimum inhibitory concentrations (MICs) of the strains against fluconazole (FLU), voriconazole (VOR), itraconazole (ITR), Posaconazole (POS), isavuconazole (ISA), anidulafungin (ANI), caspofungin (CAS), micafungin (MICA) and 5-fluorocytosine (FCT) were tested by the ThermoFisher CMC1JHY colorimetric microdilution method. The MIC of amphotericin B (AMB) was tested by the broth microdilution method. The MIC results were analyzed based on the clinical breakpoints and epidemiological cutoff values (ECV) published by the Clinical and Laboratory Standards Institute (CLSI) M27 Ed3 and M57 Ed4 documents. Data analysis was conducted using the Kruskal-Wallis test and paired t-test. Results: In total, 305 C. tropicalis isolates were collected. There were 38.0% (116/305) strains isolated from blood, 11.5% (35/305) ascites, 8.9% (27/305) catheter and 8.9% (27/305) drainage fluid. The resistance rate of C. tropicalis to FLU was 32.5%, to VOR was 28.5%, and the cross-resistance rate to FLU and VOR was 28.5%. The wild-type proportions for ITR and POS were 79.3% and 29.2% respectively. There was no significant difference in resistance rates, MIC50, and MIC90 of FLU and VOR, or in the wild-type rates of ITR and POS over five years. More than 95.0% of the isolates were susceptible to echinocandins. However, one strain was identified as being multi-drug resistant. In azole antifungals, voriconazole, itraconazole, posaconazole, and isavuconazole have similar GM MIC values. The GM MIC of fluconazole is significantly higher than that of itraconazole (t=9.95, P<0.05), posaconazole (t=9.99, P<0.05), and voriconazole (t=10.01, P<0.05), Meanwhile, among echinocandins, the GM MIC of ANI was comparable to that of CAS (t=1.17, P>0.05), both of which were significantly higher than MICA (t=11.56, P<0.05; t=4.15, P<0.05). Conclusion: The clinical isolates of C. tropicalis in East China from 2017 to 2021 were relatively susceptible to echinocandins. However, there was consistently high resistance to fluconazole and voriconazole. More intensive efforts should be made on the monitoring of drug resistance in C. tropicalis.

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.

Mutations in TAC1 and ERG11 are major drivers of triazole antifungal resistance in clinical isolates of Candida parapsilosis

ObjectivesThe aim of this study was to determine how mutations in CpERG11 and CpTAC1 contribute to fluconazole resistance in a collection of clinical isolates. MethodsSequences of CpERG11 and CpTAC1 were determined for 35 resistant Candida parapsilosis clinical isolates. A plasmid-based CRISPR-Cas9 system was used to introduce mutations leading to amino acid substitution in CpTac1 and CpErg11. Triazole susceptibility was determined by broth microdilution and E-test. Differential expression of genes mediated by CpTAC1 mutation was determined by RNA sequencing, and relative expression of individual transporter genes was assessed with RT-qPCR. ResultsSix isolates carried a mutation in CpTAC1 in combination with the CpERG11 mutation, leading to the CpErg11Y132F substitution. When introduced into susceptible isolates, this CpERG11 mutation led to a 4- to 8-fold increase in fluconazole minimum inhibitory concentrations (MIC; 0.125 μg/mL vs. 0.5 μg/mL, 0.125 μg/mL vs. 0.5 μg/mL, and 0.5 μg/mL vs. 4 μg/mL). When introduced into a susceptible isolate, the CpTAC1 mutation leading to the G650E substitution resulted in an 8-fold increase in fluconazole MIC (0.25 μg/mL vs. 2 μg/mL), whereas correction of this mutation in resistant isolates led to a 16-fold reduction in MIC (32 μg/mL vs. 2 μg/mL). CpCDR1, CpCDR1B, and CpCDR1C were overexpressed in the presence CpTac1G650E. Disruption of these genes in combination resulted in a 4-fold reduction in fluconazole MIC (32 μg/mL vs. 8 μg/mL). DiscussionThese results define the specific contribution made by the Y132F substitution in CpERG11 and demonstrate a role for activating mutations in CpTAC1 in triazole resistance in C. parapsilosis.

Development of a high-resolution melt-based assay to rapidly detect the azole-resistant Candida auris isolates.

Candida auris is a multidrug-resistant yeast that rapidly spreads, making it the leading Candidate for the next pandemic. One main leading cause of emerging resistant C. auris isolates is nonsynonymous mutations. This study aimed to detect the Y132F mutation, one of the most important azole resistance-associated mutations in the ERG-11 gene of C. auris, by developing a reliable high-resolution melt (HRM)-based method. Five C. auris isolates from Iran, plus three control isolates from other Clades were used in the study. The antifungal susceptibility testing through micro broth dilution was performed to recheck their susceptibility to three azole antifungals, including fluconazole, itraconazole, and voriconazole. Moreover, the polymerase chain reaction (PCR) sequencing of the ERG-11 gene was performed. Following the bioinformatic analysis and HRM-specific primer design, an HRM-based assay was developed and evaluated to detect ERG-11 mutations. The minimum inhibitory concentrations of fluconazole among Iranian C. auris isolates ranged from 8 to 64 μg/mL. The PCR-sequencing of the ERG-11 gene and bioinformatic analyses revealed the mutation of Y132F, a substitution consequence of A to T on codon 395 in one fluconazole-resistant isolate (IFRC4050). The developed HRM assay successfully differentiated the targeted single nucleotide polymorphism between mutant and wild types (temperature [Tm]: 81.79 ℃ - cycle threshold [CT]: 20.06 for suspected isolate). For both mutant and non-mutant isolates, the mean Tm range was 81.79-82.39 °C and the mean CT value was 20.06-22.93. These results were completely in accordance with the findings of DNA sequencing. The fast-track HRM-based method successfully detected one of the most common mechanisms of resistance in the ERG-11 gene of C. auris within 3 h. Finally, the development of more panels of HRM assays for the detection of all azole resistance mutations in C. auris ERG-11 is recommended to expand the scope of the field and facilitate the elaboration of rapid and accurate methods of antifungal resistance assessment.

In vitro sensitivity of Malassezia furfur isolates from HIV-positive and negative patients to antifungal agents

Malassezia is a lipophilic and lipid-dependent yeast genus belonging to the skin microbiota of humans and other animals. However, due to dysbiosis processes or other factors in the host, this yeast can cause different pathologies, ranging from skin diseases, such as seborrheic dermatitis, to fungemia. Isolation of Malassezia furfur has been reported in HIV-positive patients with or without skin lesions. Due to its opportunistic nature and its variable resistance to antifungal compounds, it is relevant to know the Malassezia sensitivity profiles. To determine the sensitivity to different antifungal agents, of clinical isolates of M. furfur obtained from HIV-positive or negative patients, with or without seborrheic dermatitis. Assessment of isolates sensitivity to itraconazole, voriconazole, fluconazole, and amphotericin B was performed by two techniques: (1) Broth microdilution using Clinical and Laboratory Standards Institute (CLSI) protocol M27-A3 with modifications; and (2) agar tests using Etest®. Isolates obtained from HIV patients showed an increase in the minimum inhibitory concentration of fluconazole, voriconazole, and amphotericin B, compared with those of non-HIV patients. Itraconazole was the antifungal with the lowest minimum inhibitory concentration (MIC) in most isolates. We observed differences in the sensitivity profiles of M. furfur isolates according to the context of the patient. High MIC of antifungals like fluconazole, commonly used for treating pathologies caused by Malassezia, were identified.

Clinical, Microbiological, and Molecular Characterization of Candia (Starmera) stellimalicola, a Rare Fungal Pathogen Causing Human Infections.

Candia (Starmera) stellimalicola is a yeast species spread worldwide and recovered from varieties of ecological reservoirs, but human infections are rarely reported. In this study, we reported an intra-abdominal infection case caused by C. stellimalicola and described its microbiological and molecular characteristics. C. stellimalicola strains were isolated from ascites fluid of an 82-year-old male patient having diffuse peritonitis with fever and elevated WBC counts. Routine biochemical and MALDI-TOF MS methods failed to identify the pathogenic strains. Phylogenetic analysis of 18S, 26S and internal transcribed space (ITS) rDNA regions, as well as whole-genome sequence identified the strains as C. stellimalicola. Compared with other Starmera species, C. stellimalicola had unique physiological characteristics including thermal tolerance (able to grow at 42°C), which may prompt its environmental adaptability and potential for opportunistic human infection. Fluconazole minimum inhibitory concentration (MIC) values of the strains identified in this case was 2mg/L, and the patient had a favorable outcome after receiving fluconazole treatment. In comparison, the majority of C. stellimalicola strains previously documented had high MIC values (≥ 16mg/L) to fluconazole. In conclusion, with the raise in human infections caused by rare fungal pathogens, molecular diagnostic remains the most efficient way for accurate species identification; and antifungal susceptibility testing is essential to guide proper patient management.

Investigation of fluconazole susceptibility to Candida albicans by MALDI-TOF MS and real-time PCR for CDR1, CDR2, MDR1 and ERG11

BackgroundC. albicans is a pathogenic yeast that is the most common cause of fungal infections in humans. Unfortunately, the yeast’s resistance to the antifungal medication fluconazole (FLC) is increasing; furthermore, testing its susceptibility to FLC by conventional methods takes time, resulting in treatment failure. The susceptibility of C. albicans to FLC was investigated using MALDI-TOF Mass Spectrometry and Real-time PCR tests for CDR1, CDR2, MDR1 and ERG11. Overall, 32 C. albicans strains made up of four reference strains (three FLC susceptible [S] and one FLC resistant [R], one spontaneous mutant strain [FLC susceptible-dose-dependent (SDD)] and 27 clinical strains obtained from two Thai University Hospitals) were tested for susceptibility to FLC. The following tests were performed: SensititreYeastOne and broth microdilution method, FLC resistant expression mechanism by Real-time PCR, and the major peak determination by MALDI-TOF MS.ResultsThe change of CDR1 and CDR2 mRNA expression was only significantly observed in SDD and R strains. MALDI-TOF MS was performed after incubation for six hours; the change of mass spectral intensity at range 3376–3382 m/z (major peak) was significantly related to FLC susceptibility as SDD (decreased at 4 µg/mL and increased at 8 µg/mL), S (all increased), and R (all slightly decreased or no change). All 27 clinical strains showed FLC minimum inhibitory concentrations (MIC range 0.25-2 µg/mL), no change in CDR1 and CDR2 expression and S major peak type. The FLC resistant C. albicans with CDR1and CDR2 expression may possibly affect the change of mass spectral intensity at range 3376–3382 m/z.ConclusionsThe MALDI-TOF MS may be used to simultaneously classify and predict FLC resistant C. albicans strains associated with CDR1 and CDR2 expression. Further studies are essential to clarify the methodology and improve the reliability of this assay for routine diagnosis.

Epidemiological and Clinical Characteristics, Antifungal Susceptibility, and MLST-Based Genetic Analysis of Cryptococcus Isolates in Southern Taiwan in 2013-2020.

Cryptococcal meningoencephalitis (CM) is a treatable condition, but it leads to excessive morbidity and mortality. We collected 115 non-duplicated Cryptococcus clinical isolates during 2013–2020 in southern Taiwan to perform antifungal susceptibility testing. Multi-locus sequence typing was performed on 96 strains from patients with CM (n = 47) or cryptococcemia (n = 49). In addition, the epidemiological and clinical characteristics of patients with CM during 2013–2020 (n = 47) were compared with those during 2000–2010 (n = 46). During 2013–2020, only one C. neoformans isolate (0.9%) had a fluconazole minimum inhibitory concentration of >8 μg/mL. Amphotericin B (AMB), flucytosine (5FC), and voriconazole were highly active against all C. neoformans/C. gattii isolates. The most common sequence type was ST5. Among these 47 patients with CM, cerebrospinal fluid cryptococcal antigen (CSF CrAg) titer >1024 was a significant predictor of death (odds ratio, 48.33; 95% CI, 5.17–452.06). A standard induction therapy regimen with AMB and 5FC was used for all patients during 2013–2020, but only for 2.2% of patients in 2000–2010. The in-hospital CM mortality rate declined from 39.1% during 2000–2010 to 25.5% during 2013–2020, despite there being significantly younger patients with less CSF CrAg >1024 during 2000–2010. The study provides insight into the genetic epidemiology and antifungal susceptibility of Cryptococcus strains in southern Taiwan. The recommended antifungal drugs, AMB, 5FC, and FCZ, remained active against most of the Cryptococcus strains. Early diagnosis of patients with CM and adherence to the clinical practice guidelines cannot be overemphasized to improve the outcomes of patients with CM.

Population genetics and microevolution of clinical Candida glabrata reveals recombinant sequence types and hyper-variation within mitochondrial genomes, virulence genes, and drug targets.

Candida glabrata is the second most common etiological cause of worldwide systemic candidiasis in adult patients. Genome analysis of 68 isolates from 8 hospitals across Scotland, together with 83 global isolates, revealed insights into the population genetics and evolution of C. glabrata. Clinical isolates of C. glabrata from across Scotland are highly genetically diverse, including at least 19 separate sequence types that have been recovered previously in globally diverse locations, and 1 newly discovered sequence type. Several sequence types had evidence for ancestral recombination, suggesting transmission between distinct geographical regions has coincided with genetic exchange arising in new clades. Three isolates were missing MATα1, potentially representing a second mating type. Signatures of positive selection were identified in every sequence type including enrichment for epithelial adhesins thought to facilitate fungal adhesin to human epithelial cells. In patent microevolution was identified from 7 sets of recurrent cases of candidiasis, revealing an enrichment for nonsynonymous and frameshift indels in cell surface proteins. Microevolution within patients also affected epithelial adhesins genes, and several genes involved in drug resistance including the ergosterol synthesis gene ERG4 and the echinocandin target FKS1/2, the latter coinciding with a marked drop in fluconazole minimum inhibitory concentration. In addition to nuclear genome diversity, the C. glabrata mitochondrial genome was particularly diverse, with reduced conserved sequence and conserved protein-encoding genes in all nonreference ST15 isolates. Together, this study highlights the genetic diversity within the C. glabrata population that may impact virulence and drug resistance, and 2 major mechanisms generating this diversity: microevolution and genetic exchange/recombination.

Antifungal Susceptibility Profiles and Resistance Mechanisms of Clinical Diutina catenulata Isolates With High MIC Values.

Diutina catenulata (Candida catenulata) is an ascomycete yeast species widely used in environmental and industrial research and capable of causing infections in humans and animals. At present, there are only a few studies on D. catenulata, and further research is required for its more in-depth characterization and analysis. Eleven strains of D. catenulata collected from China Hospital Invasive Fungal Surveillance Net (CHIF-NET) and the CHIF-NET North China Program were identified using matrix-assisted laser desorption ionization–time of flight mass spectrometry and internal transcribed spacer sequencing. The antifungal susceptibility of the Diutina catenulata strains was tested using the Clinical and Laboratory Standards Institute broth microdilution method and Sensititre YeastOne™. Furthermore, ERG11 and FKS1 were sequenced to determine any mutations related to azole and echinocandin resistance in D. catenulata. All isolates exhibited low minimum inhibitory concentration (MIC) values for itraconazole (0.06–0.12 μg/ml), posaconazole (0.06–0.12 μg/ml), amphotericin B (0.25–1 μg/ml), and 5-flucytosine (range, <0.06–0.12 μg/ml), whereas four isolates showed high MICs (≥4 μg/ml) for echinocandins. Strains with high MIC values for azoles showed common ERG11 mutations, namely, F126L/K143R. In addition, L139R mutations may be linked to high MICs of fluconazole. Two amino acid alterations reported to correspond to high MIC values of echinocandin, namely, F621I (F641) and S625L (S645), were found in the hot spot 1 region of FKS1. In addition, one new amino acid alteration, I1348S (I1368), was found outside of the FKS1 hot spot 2 region, and its contribution to echinocandin resistance requires future investigation. Diutina catenulata mainly infects patients with a weak immune system, and the high MIC values for various antifungals exhibited by these isolates may represent a challenge to clinical treatment.

Prophylactic Use of Fluconazole in Very Premature Infants.

Objective: To evaluate the efficacy, safety, and fungal sensitivity of prophylactic fluconazole use in very premature infants.Methods: We performed a retrospective historical comparative analysis of 196 very premature infants (113 in the prophylaxis group and 83 in the rescue group). The incidence of nosocomial fungal infection (NCFI) and pathogenic fungi, their drug sensitivity, and the minimum inhibitory concentration (MIC) of fluconazole were compared between the two groups. We also analyzed differences in short-term adverse outcomes, such as drug-induced liver or renal function disruption, fungal-attributable death, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), periventricular leukomalacia (PVL), intraventricular hemorrhage (IVH), and necrotizing enterocolitis (NEC), between the groups. The effects of the prophylactic fluconazole strategy on NCFI and short-term adverse outcomes were assessed by multivariate logistic regression.Results: Candida albicans (46.7%) and Candida glabrata (43.3%) were the main culprit pathogens causing NCFI. The incidence of NCFI was significantly lower in the prophylaxis group than in the rescue group (15.9 vs. 45.8%, P < 0.001). However, fewer fungi were completely sensitive to fluconazole (40 vs. 85%, P < 0.05) and the MIC of fluconazole was higher [16.0 (3.5 ~ 16.0) vs. 3.0 (1.0 ~ 8.0) μg/ml, P < 0.001] in the prophylaxis group than in the rescue group. Compared with the rescue group, the prophylaxis group had a lower risk of NCFI (adjusted OR 0.25; 95% CI 0.11, 0.55). Additionally, the prophylaxis group had significantly lower risks of combined outcomes (one or more complications, such as BPD, ROP needing interventions, PVL/IVH (grade > 2), NEC stage ≥2, and fungal-attributable death) (adjusted OR 0.44; 95% CI 0.21, 0.92). There was no significant difference in serum alanine transferase (ALT), aspartate transaminase (AST), creatinine (Cr), or direct bilirubin (DBIL) levels between the two groups.Conclusions: Fluconazole prophylaxis reduced NCFI and improved combined clinical outcomes in very premature infants, with no increased risks of serious short-term adverse side effects; however, the MIC of fluconazole showed significant increases. Therefore, further optimization of preventive strategies is necessary to maintain the sensitivity of fluconazole against fungal isolates.

Impact of antifungal stewardship interventions on the susceptibility of colonized Candida species in pediatric patients with malignancy

There is a worldwide concern regarding the antimicrobial resistance and the inappropriate use of antifungal agents, which had led to an ever-increasing antifungal resistance. This study aimed to identify the antifungal susceptibility of colonized Candida species isolated from pediatric patients with cancer and evaluate the clinical impact of antifungal stewardship (AFS) interventions on the antifungal susceptibility of colonized Candida species. Candida species colonization was evaluated among hospitalized children with cancer in a tertiary teaching hospital, Shiraz 2017–2018. Samples were collected from the mouth, nose, urine, and stool of the patients admitted to our center and cultured on sabouraud dextrose agar. The isolated yeasts identified by polymerase chain reaction–restriction fragment length polymorphisms (PCR–RFLP). DNA Extracted and PCR amplification was performed using the ITS1 and ITS4 primer pairs and Msp I enzyme. The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) for amphotericin B, caspofungin, and azoles. The prevalence of Candida albicans in the present study was significantly higher than other Candida species. Candida albicans species were completely susceptible to the azoles. The susceptibility rate of C. albicans to amphotericin B and caspofungin was 93.1% and 97.1%, respectively. The fluconazole MIC values of Candida albicans decreased significantly during the post-AFS period (P < 0.001; mean difference: 72.3; 95% CI of the difference: 47.36–98.62). We found that ‏52.5% (53/117) of the isolated C. albicans were azole-resistant before AFS implementation, while only 1.5% (2/102) of the isolates were resistant after implementation of the AFS program (P < 0.001). C. albicans fluconazole and caspofungin resistant rate also decreased significantly (P < 0.001) after implementation of the AFS program [26 (32.9%) versus 0 (0.0%) and 11 (10.9%) versus 1 (0.9%), respectively]. Besides, fluconazole use (p < 0.05) and fluconazole expenditure reduced significantly (about one thousand US$ per year) after the AFS program. Our results confirm the positive effect of optimized antifungal usage and bedside intervention on the susceptibility of Candida species after the implementation of the AFS program. C. albicans and C. glabrata exhibited a significant increase in susceptibility after the execution of the AFS program.

ATI-2307 Exhibits Equivalent Antifungal Activity in Cryptococcus neoformans Clinical Isolates With High and Low Fluconazole IC50.

Half maximal inhibitory concentrations (IC50) to the experimental drug ATI-2307 and complete inhibition (IC90) of the common clinically used antifungal drug amphotericin B were determined by microbroth dilution assay for a collection of 69 clinical isolates of Cryptococcus neoformans from Uganda that had high fluconazole IC50 values. The majority of the clinical isolates tested had fluconazole IC50 at or above 8 µg/mL, but were susceptible to both amphotericin B (IC90 ≤1 μg/mL) and ATI-2307 (IC50 ≤0.0312 µg/mL). No correlation between increased fluconazole minimum inhibitory concentration (MIC) and ATI-2307 or amphotericin B MIC was observed, suggesting that the cellular changes impacting fluconazole susceptibility did not impact the effectiveness of ATI-2307. Our results suggest that ATI-2307 is a promising new antifungal drug for use in the context of high fluconazole or other antifungal drug MICs and/or in combination drug therapy regimens.

In vitro activities of the tetrazole VT-1161 compared with itraconazole and fluconazole against Cryptococcus and non-albicans Candida species

ABSTRACT Recently, Cryptococcus and non-albicans Candida (NAC) have emerged as health-threatening pathogens for clinical fungal infections. Due to their increased resistance to existing antifungal drugs, novel antifungals are urgently needed. In this study, we evaluated the antifungal effect of VT-1161 and its comparators itraconazole and fluconazole against common fluconazole-sensitive or -resistant Cryptococcus and NAC strains. The tested strains were obtained from Chinese patients by the Invasive Fungal Infection Group within the past 2 years. The minimum inhibitory concentrations (MICs) of VT-1161 and other triazoles were measured according to the Clinical and Laboratory Standards Institute (CLSI) M27-Ed4 guidelines. We found that VT-1161 exhibited strong in vitro activity against Cryptococcus spp.. VT-1161 (geometric mean MIC = 0.024 μg/mL) was 21.7-fold and 104.5-fold more potent than itraconazole and fluconazole, respectively. Against the seven Cryptococcus neoformans isolates with higher fluconazole MICs (≥8 μg/mL based on the MIC90 value of this azole), VT-1161 maintained potent activities, with MICs ranging between 0.031 and 0.5 μg/mL. For NAC spp., VT-1161 (geometric mean MIC = 0.099 μg/mL) was 6.0-fold and 11.4-fold more effective than itraconazole and fluconazole, respectively. There is a positive correlation of the MICs between VT-1161 and itraconazole/fluconazole. The MIC values of VT-1161 against Candida glabrata and Candida tropicalis were significantly lower than those of fluconazole, whereas for Candida parapsilosis the differences in the MIC values between VT-1161 and fluconazole were not statistically significant. The results showed that tetrazole VT-1161 might be a promising candidate for treating Cryptococcus and NAC infections.

Genotype, Antifungal Susceptibility, and Virulence of Clinical South African Cryptococcus neoformans Strains from National Surveillance, 2005-2009.

In South Africa, Cryptococcus neoformans is the most common cause of adult meningitis. We performed multi locus sequence typing and fluconazole susceptibility testing of clinical C. neoformans isolates collected from 251 South African patients with cryptococcosis through national surveillance from 2005 to 2009. We examined the association between clinical characteristics of patients and genotype, and the effect of genotype on in-hospital mortality. We performed whole genome phylogenetic analysis of fifteen C. neoformans isolates with the molecular type VNB and tested their virulence in a Galleria mellonella model. Most isolates had the molecular type VNI (206/251, 82%), followed by VNII (25/251, 10%), VNB (15/251, 6%), and VNIV (5/251, 2%); 67 sequence types were identified. There were no differences in fluconazole minimum inhibitory concentration (MIC) values among molecular types and the majority of strains had low MIC values (MIC50 of 1 µg/mL and MIC90 of 4 µg/mL). Males were almost twice as likely of being infected with a non-VNI genotype (adjusted odds ratio [OR]: 1.65, 95% confidence interval [CI]: 0.25–10.99; p = 0.61). Compared to patients infected with a VNI genotype, those with a non-VNI genotype had a 50% reduced adjusted odds of dying in hospital (95% CI: 0.03–7.57; p = 0.62). However, for both these analyses, our estimates had wide confidence intervals spanning 1 with large p-values. Fifteen VNB strains were not as virulent in a G. mellonella larval model as the H99 reference strain. A majority of these VNB strains belonged to the VNBII clade and were very closely related by phylogenetic analysis.

Combining Colistin and Fluconazole Synergistically Increases Fungal Membrane Permeability and Antifungal Cidality.

The increasing emergence of drug-resistant fungal pathogens, together with the limited number of available antifungal drugs, presents serious clinical challenges to treating systemic, life-threatening infections. Repurposing existing drugs to augment the antifungal activity of well-tolerated antifungals is a promising antifungal strategy with the potential to be implemented rapidly. Here, we explored the mechanism by which colistin, a positively charged lipopeptide antibiotic, enhances the antifungal activity of fluconazole, the most widely used orally available antifungal. In a range of susceptible and drug-resistant isolates and species, colistin was primarily effective at reducing fluconazole tolerance, a property of subpopulations of cells that grow slowly in the presence of a drug and may promote the emergence of persistent infections and resistance. Clinically relevant concentrations of colistin synergized with fluconazole, reducing fluconazole minimum inhibitory concentration 4-fold. Combining fluconazole and colistin also increased survival in a C. albicans Galleria mellonella infection, especially for a highly fluconazole-tolerant isolate. Mechanistically, colistin increased permeability to fluorescent antifungal azole probes and to intracellular dyes, accompanied by an increase in cell death that was dependent upon pharmacological or genetic inhibition of the ergosterol biosynthesis pathway. The positive charge of colistin is critical to its antifungal, and antibacterial, activity: colistin directly binds to several eukaryotic membrane lipids (i.e., l-α-phosphatidylinositol, l-α-phosphatidyl-l-serine, and l-α-phosphatidylethanolamine) that are enriched in the membranes of ergosterol-depleted cells. These results support the idea that colistin binds to fungal membrane lipids and permeabilizes fungal cells in a manner that depends upon the degree of ergosterol depletion.