Determination of Isavuconazole Susceptibility of Aspergillus and Candida Species by the EUCAST Method

ABSTRACTIsavuconazole is a novel expanded-spectrum triazole, which has recently been approved by the FDA as an orphan drug to treat invasive aspergillosis and is currently being studied in phase III clinical trials for invasive candidiasis. The susceptibility of relatively few clinical isolates has been reported. In this study, the isavuconazole susceptibilities of 1,237Aspergillusand 2,010Candidageographically diverse clinical isolates were determined by EUCAST methodology at four European mycology laboratories, producing the largest multicenter data set thus far for this compound. In addition, a blinded collection of 30cyp51AmutantAspergillus fumigatusclinical isolates and 10 wild-type isolates was tested. From these two data sets, the following preliminary epidemiological cutoff (ECOFF) values were suggested: 2 mg/liter forAspergillus fumigatus,Aspergillus terreus, andAspergillus flavus; 4 mg/liter forAspergillus niger; 0.25 mg/liter forAspergillus nidulans; and 0.03 mg/liter forCandida albicans,Candida parapsilosis, andCandida tropicalis. Unfortunately, ECOFFs could not be determined forCandida glabrataorCandida kruseidue to an unexplained interlaboratory MIC variation. For the blinded collection ofA. fumigatusisolates, all MICs were ≤2 mg/liter for wild-type isolates. Differential isavuconazole MICs were observed for triazole-resistantA. fumigatusisolates with differentcyp51Aalterations: TR34/L98H mutants had elevated isavuconazole MICs, whereas isolates with G54 and M220 alterations had MICs in the wild-type range, suggesting that the efficacy of isavuconazole may not be affected by these alterations. This study will be an aid in interpreting isavuconazole MICs for clinical care and an important step in the future process of setting official clinical breakpoints.

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Interplay between Gliotoxin Resistance, Secretion, and the Methyl/Methionine Cycle in Aspergillus fumigatus

Eukaryotic Cell ◽

10.1128/ec.00055-15 ◽

2015 ◽

Vol 14 (9) ◽

pp. 941-957 ◽

Cited By ~ 25

Author(s):

Rebecca A. Owens ◽

Grainne O'Keeffe ◽

Elizabeth B. Smith ◽

Stephen K. Dolan ◽

Stephen Hammel ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Molecular Architecture ◽

Wild Type ◽

Content Type ◽

Excess Substrate ◽

In The Wild ◽

Methionine Cycle ◽

Key Aspects ◽

Self Protection ◽

Methylation Activity

ABSTRACTMechanistic studies on gliotoxin biosynthesis and self-protection inAspergillus fumigatus, both of which require the gliotoxin oxidoreductase GliT, have revealed a rich landscape of highly novel biochemistries, yet key aspects of this complex molecular architecture remain obscure. Here we show that anA. fumigatusΔgliAstrain is completely deficient in gliotoxin secretion but still retains the ability to efflux bisdethiobis(methylthio)gliotoxin (BmGT). This correlates with a significant increase in sensitivity to exogenous gliotoxin because gliotoxin trapped inside the cell leads to (i) activation of theglicluster, as disablingglicluster activation, viagliZdeletion, attenuates the sensitivity of anA. fumigatusΔgliTstrain to gliotoxin, thus implicating cluster activation as a factor in gliotoxin sensitivity, and (ii) increased methylation activity due to excess substrate (dithiol gliotoxin) for the gliotoxinbis-thiomethyltransferase GtmA. Intracellular dithiol gliotoxin is oxidized by GliT and subsequently effluxed by GliA. In the absence of GliA, gliotoxin persists in the cell and is converted to BmGT, with levels significantly higher than those in the wild type. Similarly, in the ΔgliTstrain, gliotoxin oxidation is impeded, and methylation occurs unchecked, leading to significantS-adenosylmethionine (SAM) depletion andS-adenosylhomocysteine (SAH) overproduction. This in turn significantly contributes to the observed hypersensitivity ofgliT-deficientA. fumigatusto gliotoxin. Our observations reveal a key role for GliT in preventing dysregulation of the methyl/methionine cycle to control intracellular SAM and SAH homeostasis during gliotoxin biosynthesis and exposure. Moreover, we reveal attenuated GliT abundance in theA. fumigatusΔgliKstrain, but not the ΔgliGstrain, following exposure to gliotoxin, correlating with relative sensitivities. Overall, we illuminate new systems interactions that have evolved in gliotoxin-producing, compared to gliotoxin-naive, fungi to facilitate their cellular presence.

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Posaconazole Prophylaxis in Experimental Azole-Resistant Invasive Pulmonary Aspergillosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03850-14 ◽

2014 ◽

Vol 59 (3) ◽

pp. 1487-1494 ◽

Cited By ~ 11

Author(s):

Seyedmojtaba Seyedmousavi ◽

Johan W. Mouton ◽

Willem J. G. Melchers ◽

Paul E. Verweij

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Murine Model ◽

Pulmonary Infection ◽

Invasive Pulmonary Aspergillosis ◽

Clinical Isolates ◽

Wild Type ◽

Breakthrough Infection ◽

Pulmonary Aspergillosis ◽

Content Type

ABSTRACTWe investigated the efficacy of posaconazole prophylaxis in preventing invasive aspergillosis due to azole-resistantAspergillus fumigatusisolates. Using a neutropenic murine model of pulmonary infection, posaconazole prophylaxis was evaluated using three isogenic clinical isolates, with posaconazole MICs of 0.063 mg/liter (wild type), 0.5 mg/liter (F219I mutation), and 16 mg/liter. A fourth isolate harboring TR34/L98H (MIC of 0.5 mg/liter) was also tested. Posaconazole prophylaxis was effective inA. fumigatuswith posaconazole MICs of ≤0.5 mg/liter, where 100% survival was reached. However, breakthrough infection was observed in mice infected with the isolate for which the posaconazole MIC was >16 mg/liter.

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Antifungal Susceptibilities of Aspergillus fumigatus Clinical Isolates Obtained in Nagasaki, Japan

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05394-11 ◽

2011 ◽

Vol 56 (1) ◽

pp. 584-587 ◽

Cited By ~ 45

Author(s):

Masato Tashiro ◽

Koichi Izumikawa ◽

Asuka Minematsu ◽

Katsuji Hirano ◽

Naoki Iwanaga ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Amphotericin B ◽

Clinical Isolates ◽

Wild Type ◽

Content Type

ABSTRACTWe investigated the triazole, amphotericin B, and micafungin susceptibilities of 196A. fumigatusclinical isolates in Nagasaki, Japan. The percentages of non-wild-type (non-WT) isolates for which MICs of itraconazole, posaconazole, and voriconazole were above the ECV were 7.1%, 2.6%, and 4.1%, respectively. A G54 mutation incyp51Awas detected in 64.2% (9/14 isolates) and 100% (5/5 isolates) of non-WT isolates for itraconazole and posaconazole, respectively. Amphotericin B MICs of ≥2 μg/ml and micafungin minimum effective concentrations (MECs) of ≥16 μg/ml were recorded for two and one isolates, respectively.

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The Serratia marcescens Siderophore Serratiochelin Is Necessary for Full Virulence during Bloodstream Infection

Infection and Immunity ◽

10.1128/iai.00117-20 ◽

2020 ◽

Vol 88 (8) ◽

Cited By ~ 1

Author(s):

Danelle R. Weakland ◽

Sara N. Smith ◽

Bailey Bell ◽

Ashootosh Tripathi ◽

Harry L. T. Mobley

Keyword(s):

Serratia Marcescens ◽

Bloodstream Infection ◽

Iron Acquisition ◽

Gene Clusters ◽

Clinical Isolates ◽

Wild Type ◽

Serratia Plymuthica ◽

Content Type ◽

Cas Assay ◽

Essential Nutrient

ABSTRACT Serratia marcescens is a bacterium frequently found in the environment, but over the last several decades it has evolved into a concerning clinical pathogen, causing fatal bacteremia. To establish such infections, pathogens require specific nutrients; one very limited but essential nutrient is iron. We sought to characterize the iron acquisition systems in S. marcescens isolate UMH9, which was recovered from a clinical bloodstream infection. Using RNA sequencing (RNA-seq), we identified two predicted siderophore gene clusters (cbs and sch) that were regulated by iron. Mutants were constructed to delete each iron acquisition locus individually and in conjunction, generating both single and double mutants for the putative siderophore systems. Mutants lacking the sch gene cluster lost their iron-chelating ability as quantified by the chrome azurol S (CAS) assay, whereas the cbs mutant retained wild-type activity. Mass spectrometry-based analysis identified the chelating siderophore to be serratiochelin, a siderophore previously identified in Serratia plymuthica. Serratiochelin-producing mutants also displayed a decreased growth rate under iron-limited conditions created by dipyridyl added to LB medium. Additionally, mutants lacking serratiochelin were significantly outcompeted during cochallenge with wild-type UMH9 in the kidneys and spleen after inoculation via the tail vein in a bacteremia mouse model. This result was further confirmed by an independent challenge, suggesting that serratiochelin is required for full S. marcescens pathogenesis in the bloodstream. Nine other clinical isolates have at least 90% protein identity to the UMH9 serratiochelin system; therefore, our results are broadly applicable to emerging clinical isolates of S. marcescens causing bacteremia.

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Pharmacodynamics of Itraconazole against Aspergillus fumigatus in anIn VitroModel of the Human Alveolus: Perspectives on the Treatment of Triazole-Resistant Infection and Utility of Airway Administration

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00141-12 ◽

2012 ◽

Vol 56 (8) ◽

pp. 4146-4153 ◽

Cited By ~ 6

Author(s):

Zaid Al-Nakeeb ◽

Ajay Sudan ◽

Adam R. Jeans ◽

Lea Gregson ◽

Joanne Goodwin ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Therapeutic Strategies ◽

Wild Type ◽

Content Type ◽

Exposure Response ◽

Prevention And Treatment ◽

Resistant Infection ◽

Resistant Strains ◽

Type Strains

ABSTRACTItraconazole is used for the prevention and treatment of infections caused byAspergillus fumigatus. An understanding of the pharmacodynamics of itraconazole against wild-type and triazole-resistant strains provides a basis for innovative therapeutic strategies for treatment of infections. Anin vitromodel of the human alveolus was used to define the pharmacodynamics of itraconazole. Galactomannan was used as a biomarker. The effect of systemic and airway administration of itraconazole was assessed, as was a combination of itraconazole administered to the airway and systemically administered 5FC. Systemically administered itraconazole against the wild type induced a concentration-dependent decline in galactomannan in the alveolar and endothelial compartments. No exposure-response relationships were apparent for the L98H, M220T, or G138C mutant. The administration of itraconazole to the airway resulted in comparable exposure-response relationships to those observed with systemic therapy. This was achieved without detectable concentrations of drug within the endothelial compartment. The airway administration of itraconazole resulted in a definite but submaximal effect in the endothelial compartment against the L98H mutant. The administration of 5FC resulted in a concentration-dependent decline in galactomannan in both the alveolar and endothelial compartments. The combination of airway administration of itraconazole and systemically administered 5FC was additive. Systemic administration of itraconazole is ineffective against Cyp51 mutants. The airway administration of itraconazole is effective for the treatment of wild-type strains and appears to have some activity against the L98H mutants. Combination with other agents, such as 5FC, may enable the attainment of near-maximal antifungal activity.

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A systematic review of machine learning-based missing value imputation techniques

Data Technologies and Applications ◽

10.1108/dta-12-2020-0298 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Tressy Thomas ◽

Enayat Rajabi

Keyword(s):

Machine Learning ◽

Selection Process ◽

Evaluation Metrics ◽

Correct Prediction ◽

Data Sets ◽

Data Set ◽

Missing Value ◽

Content Type ◽

Missing Value Imputation ◽

Literature Reviews

PurposeThe primary aim of this study is to review the studies from different dimensions including type of methods, experimentation setup and evaluation metrics used in the novel approaches proposed for data imputation, particularly in the machine learning (ML) area. This ultimately provides an understanding about how well the proposed framework is evaluated and what type and ratio of missingness are addressed in the proposals. The review questions in this study are (1) what are the ML-based imputation methods studied and proposed during 2010–2020? (2) How the experimentation setup, characteristics of data sets and missingness are employed in these studies? (3) What metrics were used for the evaluation of imputation method?Design/methodology/approachThe review process went through the standard identification, screening and selection process. The initial search on electronic databases for missing value imputation (MVI) based on ML algorithms returned a large number of papers totaling at 2,883. Most of the papers at this stage were not exactly an MVI technique relevant to this study. The literature reviews are first scanned in the title for relevancy, and 306 literature reviews were identified as appropriate. Upon reviewing the abstract text, 151 literature reviews that are not eligible for this study are dropped. This resulted in 155 research papers suitable for full-text review. From this, 117 papers are used in assessment of the review questions.FindingsThis study shows that clustering- and instance-based algorithms are the most proposed MVI methods. Percentage of correct prediction (PCP) and root mean square error (RMSE) are most used evaluation metrics in these studies. For experimentation, majority of the studies sourced the data sets from publicly available data set repositories. A common approach is that the complete data set is set as baseline to evaluate the effectiveness of imputation on the test data sets with artificially induced missingness. The data set size and missingness ratio varied across the experimentations, while missing datatype and mechanism are pertaining to the capability of imputation. Computational expense is a concern, and experimentation using large data sets appears to be a challenge.Originality/valueIt is understood from the review that there is no single universal solution to missing data problem. Variants of ML approaches work well with the missingness based on the characteristics of the data set. Most of the methods reviewed lack generalization with regard to applicability. Another concern related to applicability is the complexity of the formulation and implementation of the algorithm. Imputations based on k-nearest neighbors (kNN) and clustering algorithms which are simple and easy to implement make it popular across various domains.

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Fast and accurate detection of surface defect based on improved YOLOv4

Assembly Automation ◽

10.1108/aa-04-2021-0044 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Jiawei Lian ◽

Junhong He ◽

Yun Niu ◽

Tianze Wang

Keyword(s):

Feature Extraction ◽

Real Time ◽

Surface Defect ◽

Steel Ingot ◽

Industrial Applications ◽

Data Sets ◽

Data Set ◽

Processing Technologies ◽

Content Type ◽

Public Data

Purpose The current popular image processing technologies based on convolutional neural network have the characteristics of large computation, high storage cost and low accuracy for tiny defect detection, which is contrary to the high real-time and accuracy, limited computing resources and storage required by industrial applications. Therefore, an improved YOLOv4 named as YOLOv4-Defect is proposed aim to solve the above problems. Design/methodology/approach On the one hand, this study performs multi-dimensional compression processing on the feature extraction network of YOLOv4 to simplify the model and improve the feature extraction ability of the model through knowledge distillation. On the other hand, a prediction scale with more detailed receptive field is added to optimize the model structure, which can improve the detection performance for tiny defects. Findings The effectiveness of the method is verified by public data sets NEU-CLS and DAGM 2007, and the steel ingot data set collected in the actual industrial field. The experimental results demonstrated that the proposed YOLOv4-Defect method can greatly improve the recognition efficiency and accuracy and reduce the size and computation consumption of the model. Originality/value This paper proposed an improved YOLOv4 named as YOLOv4-Defect for the detection of surface defect, which is conducive to application in various industrial scenarios with limited storage and computing resources, and meets the requirements of high real-time and precision.

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Activation of 2,4-Diaminoquinazoline in Mycobacterium tuberculosis by Rv3161c, a Putative Dioxygenase

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01505-18 ◽

2018 ◽

Vol 63 (1) ◽

Author(s):

Eduard Melief ◽

Shilah A. Bonnett ◽

Edison S. Zuniga ◽

Tanya Parish

Keyword(s):

Mycobacterium Tuberculosis ◽

Mutant Strain ◽

Type Strain ◽

Wild Type Strain ◽

Type A ◽

Wild Type ◽

Metabolite Analysis ◽

Content Type ◽

Data Support ◽

In The Wild

ABSTRACT The diaminoquinazoline series has good potency against Mycobacterium tuberculosis. Resistant isolates have mutations in Rv3161c, a putative dioxygenase. We carried out metabolite analysis on a wild-type strain and an Rv3161c mutant strain after exposure to a diaminoquinazoline. The parental compound was found in intracellular extracts from the mutant but not the wild type. A metabolite consistent with a monohydroxylated form was identified in the wild type. These data support the hypothesis that Rv3161c metabolizes diaminoquinazolines in M. tuberculosis.

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Preexposure to Isavuconazole Increases the Virulence of Mucorales but Not Aspergillus fumigatus in a Drosophila melanogaster Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01896-18 ◽

2018 ◽

Vol 63 (2) ◽

pp. e01896-18 ◽

Cited By ~ 2

Author(s):

Sebastian Wurster ◽

Russell E. Lewis ◽

Nathaniel D. Albert ◽

Dimitrios P. Kontoyiannis

Keyword(s):

Drosophila Melanogaster ◽

Aspergillus Fumigatus ◽

Clinical Isolates ◽

Infection Model ◽

Content Type ◽

The Impact

ABSTRACT Breakthrough mucormycosis in patients receiving isavuconazole prophylaxis or therapy has been reported. We compared the impact of isavuconazole and voriconazole exposure on the virulence of clinical isolates of Aspergillus fumigatus and different Mucorales species in a Drosophila melanogaster infection model. In contrast to A. fumigatus, a hypervirulent phenotype was found in all tested Mucorales upon preexposure to either voriconazole or isavuconazole. These findings may contribute to the explanation of breakthrough mucormycosis in isavuconazole-treated patients.

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Characterization of the Proliferating Cell Nuclear Antigen of Leishmania donovani Clinical Isolates and Its Association with Antimony Resistance

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01847-13 ◽

2014 ◽

Vol 58 (6) ◽

pp. 2997-3007 ◽

Cited By ~ 9

Author(s):

Rati Tandon ◽

Sharat Chandra ◽

Rajendra Kumar Baharia ◽

Sanchita Das ◽

Pragya Misra ◽

...

Keyword(s):

Clinical Isolate ◽

Proliferating Cell Nuclear Antigen ◽

Leishmania Donovani ◽

Clinical Isolates ◽

Resistant Isolate ◽

Nuclear Antigen ◽

Wild Type ◽

Content Type ◽

Sensitive Isolate ◽

Proliferating Cell

ABSTRACTPreviously, through a proteomic analysis, proliferating cell nuclear antigen (PCNA) was found to be overexpressed in the sodium antimony gluconate (SAG)-resistant clinical isolate compared to that in the SAG-sensitive clinical isolate ofLeishmania donovani. The present study was designed to explore the potential role of the PCNA protein in SAG resistance inL. donovani. For this purpose, the protein was cloned, overexpressed, purified, and modeled. Western blot (WB) and real-time PCR (RT-PCR) analyses confirmed that PCNA was overexpressed by ≥3-fold in the log phase, stationary phase, and peanut agglutinin isolated procyclic and metacyclic stages of the promastigote form and by ∼5-fold in the amastigote form of the SAG-resistant isolate compared to that in the SAG-sensitive isolate.L. donovaniPCNA (LdPCNA) was overexpressed as a green fluorescent protein (GFP) fusion protein in a SAG-sensitive clinical isolate ofL. donovani, and modulation of the sensitivities of the transfectants to pentavalent antimonial (SbV) and trivalent antimonial (SbIII) drugs was assessedin vitroagainst promastigotes and intracellular (J774A.1 cell line) amastigotes, respectively. Overexpression of LdPCNA in the SAG-sensitive isolate resulted in an increase in the 50% inhibitory concentrations (IC50) of SbV(from 41.2 ± 0.6 μg/ml to 66.5 ± 3.9 μg/ml) and SbIII(from 24.0 ± 0.3 μg/ml to 43.4 ± 1.8 μg/ml). Moreover, PCNA-overexpressing promastigote transfectants exhibited less DNA fragmentation compared to that of wild-type SAG-sensitive parasites upon SbIIItreatment. In addition, SAG-induced nitric oxide (NO) production was found to be significantly inhibited in the macrophages infected with the transfectants compared with that in wild-type SAG-sensitive parasites. Consequently, we infer that LdPCNA has a significant role in SAG resistance inL. donovaniclinical isolates, which warrants detailed investigations regarding its mechanism.

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