scholarly journals Differences in Interactions between Azole Drugs Related to Modifications in the 14-α Sterol Demethylase Gene (cyp51A) of Aspergillus fumigatus

2005 ◽  
Vol 49 (5) ◽  
pp. 2119-2121 ◽  
Author(s):  
G. Garcia-Effron ◽  
E. Mellado ◽  
A. Gomez-Lopez ◽  
L. Alcazar-Fuoli ◽  
M. Cuenca-Estrella ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Gene Knockout ◽  
Resistance Mechanisms ◽  
Knockout Strain ◽  
Resistant Strains ◽  
Gene Knockouts

ABSTRACT The combined activity of different azole drugs was investigated. Thirty-one Aspergillus fumigatus strains were tested, including two cyp51A − and one cyp51B − gene-knockout strain and azole-susceptible and -resistant strains with different resistance mechanisms. The combination of itraconazole and voriconazole was synergistic for all strains except for those with gene knockouts.

scholarly journals Multi-resistance to non-azole fungicides in Aspergillus fumigatus TR 34 /L98H azole resistant isolates.

2021 ◽  
Author(s):  
I Gonzalez-Jimenez ◽  
R Garcia-Rubio ◽  
S Monzon ◽  
J Lucio ◽  
I Cuesta ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Plant Pathogens ◽  
Crop Protection ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Sequencing Analysis ◽  
Human Fungal Pathogen ◽  
Evolution Pattern ◽  
Environmental Setting ◽  
Resistant Strains

Drug resistance is a worldwide problem affecting all pathogens. The human fungal pathogen Aspergillus fumigatus coexists in the environment with other fungi targeted by crop protection compounds being unintentionally exposed to the selective pressure of multiple antifungal classes leading to the selection of resistant strains. A. fumigatus azole resistant isolates are emerging in both the clinical and environmental setting. Since their approval, azole drugs have dominated the clinical treatment for aspergillosis infections, and the agriculture fungicide market. However, other antifungal classes are used for crop protection including benzimidazoles (MBC), strobilurins (QoIs) and succinate dehydrogenase inhibitors (SDHIs). Mutations responsible for resistance to these fungicides have been widely researched in plant pathogens, but it has not been explored in A. fumigatus . In this work, the genetic basis underlying resistance to MBCs, QoIs and SDHIs were studied in azole susceptible and resistant A. fumigatus strains. E198A/Q and F200Y mutations in the β-tubulin conferred resistance to MBCs, G143A and F129L substitutions in the Cytochrome b to QoIs and H270R/Y mutations in SdhB to SDHIs. Characterization of the susceptibility to azoles showed a correlation between strains resistant to these fungicides and the ones with TR-based azole resistance mechanisms. Whole genome sequencing analysis showed a genetic relationship among fungicide multi resistant strains, which grouped together into subclusters that only included strains carrying the TR-based azole resistance mechanisms, indicating a common ancestor/evolution pattern and confirming the environmental origin of this type of azole resistant A. fumigatus .

scholarly journals Epidemiology and Molecular Characterizations of Azole Resistance in Clinical and Environmental Aspergillus fumigatus Isolates from China

2016 ◽  
Vol 60 (10) ◽  
pp. 5878-5884 ◽  
Author(s):  
Yong Chen ◽  
Zhongyi Lu ◽  
Jingjun Zhao ◽  
Ziying Zou ◽  
Yanwen Gong ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Antifungal Susceptibility ◽  
Public Health Problem ◽  
Wide Distribution ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Common Mutation ◽  
Content Type ◽  
Environmental Resistance ◽  
Resistant Strains

ABSTRACTAzole resistance inAspergillus fumigatushas emerged as a worldwide public health problem. We sought here to demonstrate the occurrence and characteristics of azole resistance inA. fumigatusfrom different parts of China. A total of 317 clinical and 144 environmentalA. fumigatusisolates from 12 provinces were collected and subjected to screening for azole resistance. Antifungal susceptibility,cyp51Agene sequencing, and genotyping were carried out for all suspected azole-resistant isolates and a subset of azole-susceptible isolates. As a result, 8 (2.5%) clinical and 2 (1.4%) environmentalA. fumigatusisolates were identified as azole resistant. Five azole-resistant strains exhibit the TR34/L98H mutation, whereas four carry the TR34/L98H/S297T/F495I mutation in thecyp51Agene. Genetic typing and phylogenetic analysis showed that there was a worldwide clonal expansion of the TR34/L98H isolates, while the TR34/L98H/S297T/F495I isolates from China harbored a distinct genetic background with resistant isolates from other countries. High polymorphisms existed in thecyp51Agene that produced amino acid changes among azole-susceptibleA. fumigatusisolates, with N248K being the most common mutation. These data suggest that the wide distribution of azole-resistantA. fumigatusmight be attributed to the environmental resistance mechanisms in China.

scholarly journals Hospital Environment as a Source of Azole-Resistant Aspergillus fumigatus Strains with TR34/L98H and G448S Cyp51A Mutations

2021 ◽  
Vol 7 (1) ◽  
pp. 22
Author(s):  
Irene Gonzalez-Jimenez ◽  
Jose Lucio ◽  
Maria Dolores Menéndez-Fraga ◽  
Emilia Mellado ◽  
Teresa Peláez
Keyword(s):  
Treatment Failure ◽  
Aspergillus Fumigatus ◽  
High Resistance ◽  
Resistance Mechanisms ◽  
Hospital Environment ◽  
Azole Resistance ◽  
Therapy Failure ◽  
Naive Patient ◽  
Resistant Strains ◽  
Effective Analysis

Azole-resistant Aspergillus fumigatus is an emerging worldwide problem with increasing reports of therapy failure cases produced by resistant isolates. A case of azole-resistant A. fumigatus hospital colonization in a patient is reported here. Investigations of the hospital environment led to the recovery of A. fumigatus strains harboring the TR34/L98H and the G448S Cyp51A azole resistance mechanisms. Isolate genotyping showed that one strain from the environment was isogenic with the patient strains. These are the first environmental A. fumigatus azole resistant strains collected in a hospital in Spain; it supports the idea of the hospital environment as a source of dissemination and colonization/infection by azole resistant A. fumigatus in patients. The isolation of an azole-resistant strain from an azole-naïve patient is an interesting finding, suggesting that an effective analysis of clinical and environmental sources must be done to detect azole resistance in A. fumigatus. The emergence and spread of these resistance mechanisms in A. fumigatus is of major concern because it confers high resistance to voriconazole and is associated with treatment failure in patients with invasive aspergillosis.

scholarly journals Are Point Mutations in HMG-CoA Reductases (Hmg1 and Hmg2) a Step towards Azole Resistance in Aspergillus fumigatus?

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5975
Author(s):  
Irene Gonzalez-Jimenez ◽  
Jose Lucio ◽  
Alejandra Roldan ◽  
Laura Alcazar-Fuoli ◽  
Emilia Mellado
Keyword(s):  
Aspergillus Fumigatus ◽  
Structural Changes ◽  
Survival Rates ◽  
Point Mutations ◽  
Resistance Mechanisms ◽  
Ergosterol Biosynthesis ◽  
Azole Resistance ◽  
Recent Emergence ◽  
Resistant Strains

Invasive aspergillosis, mainly caused by Aspergillus fumigatus, can lead to severe clinical outcomes in immunocompromised individuals. Antifungal treatment, based on the use of azoles, is crucial to increase survival rates. However, the recent emergence of azole-resistant A. fumigatus isolates is affecting the efficacy of the clinical therapy and lowering the success rate of azole strategies against aspergillosis. Azole resistance mechanisms described to date are mainly associated with mutations in the azole target gene cyp51A that entail structural changes in Cyp51A or overexpression of the gene. However, strains lacking cyp51A modifications but resistant to clinical azoles have recently been detected. Some genes have been proposed as new players in azole resistance. In this study, the gene hmg1, recently related to azole resistance, and its paralogue hmg2 were studied in a collection of fifteen azole-resistant strains without cyp51A modifications. Both genes encode HMG-CoA reductases and are involved in the ergosterol biosynthesis. Several mutations located in the sterol sensing domain (SSD) of Hmg1 (D242Y, G307D/S, P309L, K319Q, Y368H, F390L and I412T) and Hmg2 (I235S, V303A, I312S, I360F and V397C) were detected. The role of these mutations in conferring azole resistance is discussed in this work.

scholarly journals 1280. In-Vitro Activity of Cefiderocol, Imipenem/Relebactam, & Ceftazidime/Avibactam in Ceftolozane/Tazobactam Resistant Strains of Multidrug Resistant Pseudomonas aeruginosa

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S655-S655
Author(s):  
Daniel Navas ◽  
Angela Charles ◽  
Amy Carr ◽  
Jose Alexander
Keyword(s):  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Vitro Activity ◽  
Clinical Isolates ◽  
Resistance Testing ◽  
Clinical Samples ◽  
In Vitro Activity ◽  
Carbapenemase Gene ◽  
Resistant Strains

Abstract Background The activity of imipenem/relebactam (I/R), ceftazidime/avibactam (CZA) and cefiderocol (FDC) were evaluated against clinical isolates of multidrug resistant (MDR) strains of P. aeruginosa which was resistant to ceftolozane/tazobactam (C/T). The recent increase of MDR P. aeruginosa strains isolated from clinical samples has prompted research and development of new antimicrobials that can withstand its multiple resistance mechanisms. C/T is an effective option for treatment of MDR P. aeruginosa in our facility with only 10% of resistance in MDR strains, but the emergence of resistance may occur due to the presence of a carbapenemase gene or an ampC mutation. Methods Antimicrobial susceptibility testing for C/T Etest® (bioMérieux, Inc.) were performed on all MDR strains initially screened by the VITEK2® (bioMérieux, Inc.). 10% (n=20) of all MDR isolates were resistant to C/T by the CLSI 2019 breakpoints. These resistant isolates were tested for presence of a carbapenemase gene using the GeneXpert CARBA-R (Cepheid®) PCR and against CZA Etest® (bioMérieux, Inc.) I/R gradient strips (Liofilchem®) and FDC broth microdilution (Thermo Scientific™ Sensititre™). Results A total of 20 clinical isolates of MDR P. aeruginosa resistant to C/T were tested following standardized CLSI protocols and techniques. All 20 isolates were screened for the presence of a carbapenemase gene (blaVIM, blaNDM, blaKPC, blaOXA-48, blaIMP). A blaVIM gene was detected in 6 (30%) out of 20 isolates. FDC demonstrated the greatest activity with 85% (n=17) of susceptible isolates (CLSI MIC <4µg/dL). CZA (CLSI MIC <8µg/dL) and I/R (FDA MIC <2µg/dL) showed 15% (n=3) and 10% (n=2) of susceptible isolates respectively. FDC was active against all 6 blaVIM isolates, where all 6 strains were resistant to CZA and I/R as expected. 3 isolates tested non-susceptible against FDC; additional characterization was not performed at this time. Conclusion Based on these results, FDC demonstrated the greatest in-vitro activity against C/T resistant strains of MDR P. aeruginosa. FDC also demonstrated activity against all 6 MDR P. aeruginosa carrying blaVIM gene. FDC is a strong option to consider on MDR P. aeruginosa strains based on a resistance testing algorithm and a cost/effective protocol. Disclosures All Authors: No reported disclosures

scholarly journals An Efficient, Rapid, and Recyclable System for CRISPR-Mediated Genome Editing in Candida albicans

mSphere ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Namkha Nguyen ◽  
Morgan M. F. Quail ◽  
Aaron D. Hernday
Keyword(s):  
Candida Albicans ◽  
Genome Editing ◽  
Fungal Pathogen ◽  
Gene Knockout ◽  
Strain Engineering ◽  
Molecular Genetic Analysis ◽  
Content Type ◽  
Highly Efficient ◽  
Discovery Research ◽  
Gene Knockouts

ABSTRACT Candida albicans is the most common fungal pathogen of humans. Historically, molecular genetic analysis of this important pathogen has been hampered by the lack of stable plasmids or meiotic cell division, limited selectable markers, and inefficient methods for generating gene knockouts. The recent development of clustered regularly interspaced short palindromic repeat(s) (CRISPR)-based tools for use with C. albicans has opened the door to more efficient genome editing; however, previously reported systems have specific limitations. We report the development of an optimized CRISPR-based genome editing system for use with C. albicans. Our system is highly efficient, does not require molecular cloning, does not leave permanent markers in the genome, and supports rapid, precise genome editing in C. albicans. We also demonstrate the utility of our system for generating two independent homozygous gene knockouts in a single transformation and present a method for generating homozygous wild-type gene addbacks at the native locus. Furthermore, each step of our protocol is compatible with high-throughput strain engineering approaches, thus opening the door to the generation of a complete C. albicans gene knockout library. IMPORTANCE Candida albicans is the major fungal pathogen of humans and is the subject of intense biomedical and discovery research. Until recently, the pace of research in this field has been hampered by the lack of efficient methods for genome editing. We report the development of a highly efficient and flexible genome editing system for use with C. albicans. This system improves upon previously published C. albicans CRISPR systems and enables rapid, precise genome editing without the use of permanent markers. This new tool kit promises to expedite the pace of research on this important fungal pathogen.

scholarly journals 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

2012 ◽  
Vol 56 (8) ◽  
pp. 4146-4153 ◽  
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.

scholarly journals Emergence of Resistance Mutations in Salmonella enterica Serovar Typhi Against Fluoroquinolones

2017 ◽  
Vol 4 (4) ◽  
Author(s):  
Takashi Matono ◽  
Masatomo Morita ◽  
Koji Yahara ◽  
Ken-ichi Lee ◽  
Hidemasa Izumiya ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Evolutionary Process ◽  
Resistance Mechanisms ◽  
Single Mutation ◽  
Nucleotide Polymorphisms ◽  
Resistance Mutations ◽  
Single Nucleotide ◽  
Salmonella Enterica Serovar Typhi ◽  
Resistant Strains ◽  
Emergence Of Resistance

Abstract Background Little is known about the evolutionary process and emergence time of resistance mutations to fluoroquinolone in Salmonella enterica serovar Typhi. Methods We analyzed S. Typhi isolates collected from returned travelers between 2001 and 2016. Based on ciprofloxacin susceptibility, isolates were categorized as highly resistant (minimum inhibitory concentration [MIC] ≥ 4 μg/mL [CIPHR]), resistant (MIC = 1–2 μg/mL [CIPR]), intermediate susceptible (MIC = 0.12–0.5 μg/mL [CIPI]), and susceptible (MIC ≤ 0.06 μg/mL [CIPS]). Results A total of 107 isolates (33 CIPHR, 14 CIPR, 30 CIPI, and 30 CIPS) were analyzed by whole-genome sequencing; 2461 single nucleotide polymorphisms (SNPs) were identified. CIPS had no mutations in the gyrA or parC genes, while each CIPI had 1 of 3 single mutations in gyrA (encoding Ser83Phe [63.3%], Ser83Tyr [33.3%], or Asp87Asn [3.3%]). CIPHR had the same 3 mutations: 2 SNPs in gyrA (encoding Ser83Phe and Asp87Asn) and a third in parC (encoding Ser80Ile). CIPHR shared a common ancestor with CIPR and CIPI isolates harboring a single mutation in gyrA encoding Ser83Phe, suggesting that CIPHR emerged 16 to 23 years ago. Conclusions Three SNPs—2 in gyrA and 1 in parC—are present in S. Typhi strains highly resistant to fluoroquinolone, which were found to have evolved in 1993–2000, approximately 10 years after the beginning of the ciprofloxacin era. Highly resistant strains with survival advantages arose from strains harboring a single mutation in gyrA encoding Ser83Phe. Judicious use of fluoroquinolones is warranted to prevent acceleration of such resistance mechanisms in the future.

scholarly journals Aromatic Polyketides from a Symbiotic Strain Aspergillus fumigatus D and Characterization of Their Biosynthetic Gene D8.t287

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 324
Author(s):  
Yi Hua ◽  
Rui Pan ◽  
Xuelian Bai ◽  
Bin Wei ◽  
Jianwei Chen ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Polyketide Synthase ◽  
Gene Knockout ◽  
Gene Clusters ◽  
Inhibitory Effect ◽  
Genomic Feature ◽  
Biosynthetic Gene ◽  
Aromatic Polyketides ◽  
Staphyloccocus Aureus ◽  
Coastal Plant

The chemical investigation of one symbiotic strain, Aspergillus fumigatus D, from the coastal plant Edgeworthia chrysantha Lindl led to the isolation of eight compounds (1–8), which were respectively identified as rubrofusarin B (1), alternariol 9-O-methyl ether (2), fonsecinone D (3), asperpyrone A (4), asperpyrone D (5), fonsecinone B (6), fonsecinone A (7), and aurasperone A (8) by a combination of spectroscopic methods (1D NMR and ESI-MS) as well as by comparison with the literature data. An antimicrobial assay showed that these aromatic polyketides exhibited no remarkable inhibitory effect on Escherichia coli, Staphyloccocus aureus and Candida albicans. The genomic feature of strain D was analyzed, as well as its biosynthetic gene clusters, using antibiotics and Secondary Metabolite Analysis Shell 5.1.2 (antiSMASH). Plausible biosynthetic pathways for dimeric naphtho-γ-pyrones 3–8 were first proposed in this work. A non-reducing polyketide synthase (PKS) gene D8.t287 responsible for the biosynthesis of these aromatic polyketides 1–8 was identified and characterized by target gene knockout experiment and UPLC-MS analysis.

scholarly journals Taking nature into lab: biomineralization by heavy metal resistant streptomycetes in soil

2013 ◽  
Vol 10 (2) ◽  
pp. 2345-2375 ◽  
Author(s):  
E. Schütze ◽  
A. Weist ◽  
M. Klose ◽  
T. Wach ◽  
M. Schumann ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Resistance Mechanisms ◽  
Metal Resistance ◽  
Control Soil ◽  
Natural Conditions ◽  
Laboratory Methods ◽  
Dominant Property ◽  
Resistant Strains ◽  
Heavy Metal Resistant ◽  
And Control

Abstract. Biomineralization by heavy metal resistant streptomycetes was tested to evaluate the potential influence on metal mobilities in soil. Thus, we designed an experiment adopting conditions from classical laboratory methods to natural conditions prevailing in metal-rich soils with media spiked with heavy metals, soil agar, and nutrient enriched or unamended soil incubated with the bacteria. As a result, all strains were able to form struvite minerals on tryptic soy broth (TSB) media supplemented with AlCl2, MnCl2 and CuSO4, as well as on soil agar. Some strains additionally formed struvite on nutrient enriched contaminated and control soil, as well as on metal contaminated soil without addition of media components. In contrast, switzerite was exclusively formed on minimal media spiked with MnCl2 by four heavy metal resistant strains, and on nutrient enriched control soil by one strain. Hydrated nickel hydrogen phosphate was only crystallized on complex media supplemented with NiSO4 by most strains. Thus, mineralization is a~dominant property of streptomycetes, with different processes likely to occur under laboratory conditions and sub-natural to natural conditions. This new understanding may be transferred to formation of minerals in rock and sediment evolution, to ore deposit formation, and also might have implications for our understanding of biological metal resistance mechanisms. We assume that biogeochemical cycles, nutrient storage and metal resistance might be affected by formation and re-solubilization of minerals like struvite in soil at microscale.

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