scholarly journals Insights into the Multi-Azole Resistance Profile in Candida haemulonii Species Complex

2020 ◽  
Vol 6 (4) ◽  
pp. 215
Author(s):  
Laura Nunes Silva ◽  
Lívia de Souza Ramos ◽  
Simone Santiago Carvalho Oliveira ◽  
Lucas Barros Magalhães ◽  
Eamim Daidrê Squizani ◽  
...  
Keyword(s):  
Species Complex ◽  
Fungal Pathogens ◽  
Rhodamine 6G ◽  
Efflux Pump ◽  
Antifungal Susceptibility ◽  
Cross Resistance ◽  
Azole Resistance ◽  
Candida Spp ◽  
Resistance Profile ◽  
Candida Haemulonii

The Candida haemulonii complex (C. duobushaemulonii, C. haemulonii, and C. haemulonii var. vulnera) is composed of emerging, opportunistic human fungal pathogens able to cause invasive infections with high rates of clinical treatment failure. This fungal complex typically demonstrates resistance to first-line antifungals, including fluconazole. In the present work, we have investigated the azole resistance mechanisms expressed in Brazilian clinical isolates forming the C. haemulonii complex. Initially, 12 isolates were subjected to an antifungal susceptibility test, and azole cross-resistance was detected in almost all isolates (91.7%). In order to understand the azole resistance mechanistic basis, the efflux pump activity was assessed by rhodamine-6G. The C. haemulonii complex exhibited a significantly higher rhodamine-6G efflux than the other non-albicans Candida species tested (C. tropicalis, C. krusei, and C. lusitaneae). Notably, the efflux pump inhibitors (Phe-Arg and FK506) reversed the fluconazole and voricolazole resistance phenotypes in the C. haemulonii species complex. Expression analysis indicated that the efflux pump (ChCDR1, ChCDR2, and ChMDR1) and ERG11 genes were not modulated by either fluconazole or voriconazole treatments. Further, ERG11 gene sequencing revealed several mutations, some of which culminated in amino acid polymorphisms, as previously reported in azole-resistant Candida spp. Collectively, these data point out the relevance of drug efflux pumps in mediating azole resistance in the C. haemulonii complex, and mutations in ERG11p may contribute to this resistance profile.

scholarly journals Increasing Prevalence of Multidrug-Resistant Candida haemulonii Species Complex among All Yeast Cultures Collected by a Reference Laboratory over the Past 11 Years

2020 ◽  
Vol 6 (3) ◽  
pp. 110 ◽  
Author(s):  
Soraia Lopes Lima ◽  
Elaine Cristina Francisco ◽  
João Nóbrega de Almeida Júnior ◽  
Daniel Wagner de Castro Lima Santos ◽  
Fabiane Carlesse ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Species Complex ◽  
Antifungal Susceptibility ◽  
Its Region ◽  
Multidrug Resistant ◽  
Sensu Stricto ◽  
Culture Collection ◽  
Reference Laboratory ◽  
Yeast Cultures ◽  
Candida Haemulonii

There is worldwide concern with the increasing rates of infections due to multiresistant Candida isolates reported in tertiary medical centers. We checked for historical trends in terms of prevalence rates and antifungal susceptibility of the Candida haemulonii species complex in our yeast stock culture collected during the last 11 years. The isolates were identified by sequencing the rDNA internal transcribed spacer (ITS) region, and antifungal susceptibility tests for amphotericin B, voriconazole, fluconazole, anidulafungin, and 5-fluorocytosine were performed by the Clinical and Laboratory Standards Institute (CLSI) microbroth method. A total of 49 isolates were identified as Candida haemulonii sensu stricto (n = 21), followed by C. haemulonii var. vulnera (n = 15) and C. duobushaemulonii (n = 13), including 38 isolates cultured from patients with deep-seated Candida infections. The prevalence of the C. haemulonii species complex increased from 0.9% (18 isolates among 1931) in the first period (December 2008 to June 2013) to 1.7% (31 isolates among 1868) in the second period (July 2014 to December 2019) of analysis (p = 0.047). All isolates tested exhibited high minimum inhibition concentrations for amphotericin B and fluconazole, but they remained susceptible to 5-fluorocytosine and anidulafungin. We were able to demonstrate the increased isolation of the multiresistant Candida haemulonii species complex in our culture collection, where most isolates were cultured from patients with deep-seated infections.

Efflux pump inhibition controls growth and enhances antifungal susceptibility of Fusarium solani species complex

2020 ◽  
Vol 15 (1) ◽  
pp. 9-20
Author(s):  
Rossana de A Cordeiro ◽  
Fernando VM Portela ◽  
Lívia MG Pereira ◽  
Ana RC de Andrade ◽  
José K de Sousa ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
Species Complex ◽  
Efflux Pump ◽  
Antifungal Susceptibility ◽  
Indirect Evidence ◽  
Efflux Pumps ◽  
Fusarium Solani Species Complex ◽  
Efflux Pump Inhibition ◽  
Pump Activity ◽  
Increased Sensitivity

Aim: To evaluate the inhibition of efflux pumps by using promethazine (PMZ) as a strategy to control Fusarium solani species complex (FSSC). Materials & methods: The susceptibility of FSSC strains to PMZ and the interaction between PMZ and antifungals were evaluated. The efflux pump activity was confirmed by flow cytometry with rhodamine 6G. Finally, PMZ was tested against FSSC biofilms. Results: PMZ inhibited FSSC planktonic growth and showed synergism with antifungals. PMZ reduced R6G efflux and inhibited cell adhesion, impaired the development of biofilms and disrupted mature biofilms. PMZ-challenged biofilms showed increased sensitivity to amphotericin B. Conclusion: The study provides indirect evidence of the occurrence of efflux pumps in FSSC and opens a perspective for this target in the control of fusariosis.

scholarly journals Mechanisms of Azole Resistance in a Clinical Isolate of Candida tropicalis

2005 ◽  
Vol 49 (11) ◽  
pp. 4608-4615 ◽  
Author(s):  
Patrick Vandeputte ◽  
Gérald Larcher ◽  
Thierry Bergès ◽  
Gilles Renier ◽  
Dominique Chabasse ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Clinical Isolate ◽  
Candida Tropicalis ◽  
Rhodamine 6G ◽  
Respiratory Activity ◽  
Antifungal Susceptibility ◽  
Resistant Isolate ◽  
Diffusion Method ◽  
Azole Resistance ◽  
Pathogenic Yeast

ABSTRACT Azole resistance has been insufficiently investigated in the yeast Candida tropicalis. Here we determined the molecular mechanisms responsible for azole resistance in a clinical isolate of this pathogenic yeast. Antifungal susceptibility testing performed by a disk diffusion method showed resistance or markedly decreased susceptibility to azoles, which was confirmed by determination of MICs. Considering the relationship between azole susceptibility and the respiration reported for other yeast species, the respiratory activity of this isolate was investigated. Flow cytometry using rhodamine 123 and oxygraphy demonstrated an increased respiratory activity, which was not linked to an overexpression or increased number of copies of the mitochondrial genome. Among previously described resistance mechanisms, an increased activity of efflux pumps was investigated by flow cytometry using rhodamine 6G. However, the efflux of rhodamine 6G was lower in the resistant isolate than in susceptible ones. Likewise, real-time reverse transcription-PCR quantification of the expression of C. tropicalis MDR1 (CtMDR1), which encodes an efflux protein belonging to the major facilitator superfamily, did not show overexpression of this gene. In contrast, the resistant isolate overexpressed the CtERG11 gene coding for lanosterol 14α-demethylase. This was in agreement with the larger amount of ergosterol found in this isolate. Moreover, sequencing of CtERG11 showed a point mutation leading to a tyrosine substitution in the protein sequence, which might lead to decreased binding affinity for azoles. In conclusion, overexpression of CtERG11 associated with a missense mutation in this gene seemed to be responsible for the acquired azole resistance of this clinical isolate.

scholarly journals Antimicrobial resistance among fungi from patients with urinary tract infections in Ojo, Lagos, Nigeria

2021 ◽  
Vol 14 (03) ◽  
pp. 254-264
Author(s):  
Dauphin Dighitoghi Moro ◽  
Oluwole Moses David
Keyword(s):  
Urinary Tract ◽  
Amphotericin B ◽  
Urinary Tract Infections ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Antifungal Susceptibility ◽  
Candida Spp ◽  
Fungal Isolates ◽  
Vaginal Swabs ◽  
Tract Infections

The incidence of fungal urinary tract infections has risen gradually and has thus constituted a public health challenge. The aim of this study was to determine the prevalence of urinary tract infections by fungi in two health centres in Ojo, Lagos. A total of 200 patients attending the health centers constituting 160 males’ urines and 40 females’ vaginal swabs were recruited for this study. Midstream urine samples and vaginal swabs were aseptically collected and processed using standard mycological techniques. Fungal isolates were identified based on cultural characteristics, lactophenol blue stain, chlamydospore formation, colony colour on CHROM agar Candida medium and API yeast identification. Antifungal susceptibility testing of the isolates was performed by using the Broth dilution and Kirby-Bauer disk diffusion methods using two of the most commonly used antifungal agents. A total of 122 fungal isolates, of which 68 (55.7%) were Candida spp. and 54(44.3%) Aspergillus spp. were recovered. The Candida spp. included 64 (52.5%) C. albicans and 4(3.3%) C. glabrata while Aspergillus spp. included A. flavus, 20(16.4%), A. fumigatus, 24 (19.8%) and A niger, 10(8.2%). The most common fungal pathogens in the urinary tracts of the subjects were Candida albicans and Aspergillus fumigatus. Both C. albicans and A. fumigatus were highly susceptible to both fluconazole and amphotericin B in dimethyl sulphoxide and water (90-100%). Similarly, all Aspergillus spp. were susceptible to both antifungals except A. flavus which showed a slight resistance (10-15%), which appears to be emerging. Both fluconazole and amphotericin B still show high chances of therapeutic efficacy against fungal infections of the urinary tracts.

scholarly journals Azole resistance in Candida spp. isolated from Catú Lake, Ceará, Brazil: an efflux-pump-mediated mechanism

2016 ◽  
Vol 47 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Raimunda S.N. Brilhante ◽  
Manoel A.N. Paiva ◽  
Célia M.S. Sampaio ◽  
Débora S.C.M. Castelo-Branco ◽  
Carlos E.C. Teixeira ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Azole Resistance ◽  
Candida Spp

scholarly journals In VitroActivity of Isavuconazole against Opportunistic Fungal Pathogens from Two Mycology Reference Laboratories

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Michael A. Pfaller ◽  
Paul R. Rhomberg ◽  
Nathan P. Wiederhold ◽  
Connie Gibas ◽  
Carmita Sanders ◽  
...  
Keyword(s):  
Species Complex ◽  
Fungal Pathogens ◽  
Antifungal Agents ◽  
Antifungal Susceptibility ◽  
Wild Type ◽  
Content Type ◽  
Excellent Activity ◽  
Comparable Activity ◽  
Yeasts And Molds ◽  
Susceptibility Patterns

ABSTRACTMonitoring antifungal susceptibility patterns for new and established antifungal agents seems prudent given the increasing prevalence of uncommon species associated with higher antifungal resistance. We evaluated the activity of isavuconazole against 4,856 invasive yeasts and molds collected worldwide. The 4,856 clinical fungal isolates, including 2,351Candidaspecies isolates, 97 non-Candidayeasts, 1,972Aspergillusspecies isolates, and 361 non-Aspergillusmolds, including 292Mucoralesisolates collected in 2015 to 2016, were tested using CLSI methods. The MIC values for isavuconazole versusAspergillusranged from 0.06 to ≥16 μg/ml. The modal MIC for isavuconazole was 0.5 μg/ml (range, 0.25 [A. nidulansandA. terreusspecies complex] to 4 μg/ml [A. calidoustusandA. tubingensis]). EightA. fumigatusisolates had elevated isavuconazole MIC values at ≥8 μg/ml (non-wild type). Isavuconazole showed comparable activity to itraconazole against theMucorales. The lowest modal isavuconazole MIC values were seen forRhizopusspp.,R. arrhizusvar.arrhizus, andR. microsporus(all 1 μg/ml).Candidaspecies isolates were inhibited by ≤0.25 μg/ml of isavuconazole (range, 96.1% [C. lusitaniae] to 100.0% [C. albicans,C. dubliniensis,C. kefyr, andC. orthopsilosis]). MIC values were ≤1 μg/ml for 95.5% ofC. glabrataisolates and 100.0% ofC. kruseiisolates. Isavuconazole was active against the non-Candidayeasts, includingCryptococcus neoformans(100.0% at ≤0.5 μg/ml). Isavuconazole exhibited excellent activity against most species ofCandidaandAspergillus. Isavuconazole was comparable to posaconazole and voriconazole against the less common yeasts and molds. Isavuconazole was generally less active than posaconazole and more active than voriconazole against the 292Mucoralesisolates. We confirm the potentially useful activity of isavuconazole against species ofRhizopusas determined by CLSI methods.

scholarly journals The C2H2 Transcription Factor SltA Contributes to Azole Resistance by Coregulating the Expression of the Drug Target Erg11A and the Drug Efflux Pump Mdr1 in Aspergillus fumigatus

2021 ◽  
Author(s):  
Wenlong Du ◽  
Pengfei Zhai ◽  
Tingli Wang ◽  
Michael J Bromley ◽  
Yuanwei Zhang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Fungal Pathogens ◽  
Efflux Pump ◽  
Antifungal Drugs ◽  
Ergosterol Biosynthesis ◽  
Azole Resistance ◽  
Drug Efflux ◽  
Mobility Shift ◽  
Drug Efflux Pump

The emergence of azole-resistant fungal pathogens has posed a great threat to public health worldwide. Although the molecular mechanism of azole resistance has been extensively investigated, the potential regulators of azole resistance remain largely unexplored. Here we identified a new function of the fungal specific C2H2 zinc finger transcription factor SltA (involved in salt-tolerance pathway) in the regulation of azole resistance of the human fungal pathogen Aspergillus fumigatus. Lack of SltA results in an itraconazole hypersusceptibility phenotype. Transcriptional profiling combined with LacZ reporter analysis and electrophoretic mobility shift assays (EMSA) demonstrate that SltA is involved in its own transcriptional regulation and also regulates the expression of genes related to ergosterol biosynthesis (erg11A, erg13A and erg24A) and drug efflux pumps (mdr1, mfsC and abcE) by directly binding to the conserved 5’-AGGCA-3’ motif in their promoter regions, and this binding is dependent on the conserved cysteine and histidine within the C2H2 DNA binding domain of SltA. Moreover, overexpression of erg11A or mdr1 rescues sltA deletion defects under itraconazole conditions, suggesting that erg11A and mdr1 are related to sltA-mediated itraconazole resistance. Most importantly, deletion of SltA in laboratory-derived and clinical azole-resistant isolates significantly attenuates drug resistance. Collectively, we have identified a new function of the transcription factor SltA in regulating azole resistance by coordinately mediating the key azole target Erg11A and the drug efflux pump Mdr1, and targeting SltA may provide a potential strategy for intervention of clinical azole-resistant isolates to improve the efficiency of currently approved antifungal drugs.

Surface, adhesiveness and virulence aspects of Candida haemulonii species complex

2020 ◽  
Vol 58 (7) ◽  
pp. 973-986 ◽  
Author(s):  
Lívia S Ramos ◽  
Simone S C Oliveira ◽  
Laura N Silva ◽  
Marcela Q Granato ◽  
Diego S Gonçalves ◽  
...  
Keyword(s):  
Species Complex ◽  
Galleria Mellonella ◽  
Fungal Infections ◽  
Neutral Lipids ◽  
Clinical Manifestations ◽  
Cell Surface Hydrophobicity ◽  
Candida Spp ◽  
Murine Macrophages ◽  
Candida Haemulonii

Abstract The emerging opportunistic pathogens comprising the Candida haemulonii complex (C. haemulonii [Ch], C. duobushaemulonii [Cd] and C. haemulonii var. vulnera[Chv]) are notable for their intrinsic antifungal resistance. Different clinical manifestations are associated with these fungal infections; however, little is known about their biology and potential virulence attributes. Herein, we evaluated some surface properties of 12 clinical isolates of Ch (n = 5), Cd (n = 4) and Chv (n = 3) as well as their virulence on murine macrophages and Galleria mellonella larvae. Scanning electron microscopy demonstrated the presence of homogeneous populations among the species of the C. haemulonii complex, represented by oval yeasts with surface irregularities able to form aggregates. Cell surface hydrophobicity was isolate-specific, exhibiting high (16.7%), moderate (25.0%) and low (58.3%) hydrophobicity. The isolates had negative surface charge, except for one. Mannose/glucose- and N-acetylglucosamine-containing glycoconjugates were evidenced in considerable amounts in all isolates; however, the surface expression of sialic acid was poorly detected. Cd isolates presented significantly higher amounts of chitin than Ch and Chv. Membrane sterol and lipid bodies, containing neutral lipids, were quite similar among all fungi studied. All isolates adhered to inert surfaces in the order: polystyrene > poly-L-lysine-coated glass > glass. Likewise, they interacted with murine macrophages in a quite similar way. Regarding in vivo virulence, the C. haemulonii species complex were able to kill at least 80% of the larvae after 120 hours. Our results evidenced the ability of C. haemulonii complex to produce potential surface-related virulence attributes, key components that actively participate in the infection process described in Candida spp.

scholarly journals cyp51A Mutations, Extrolite Profiles, and Antifungal Susceptibility in Clinical and Environmental Isolates of the Aspergillus viridinutans Species Complex

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Jessica J. Talbot ◽  
Jens C. Frisvad ◽  
Jacques F. Meis ◽  
Ferry Hagen ◽  
Paul E. Verweij ◽  
...  
Keyword(s):  
Species Complex ◽  
Antifungal Susceptibility ◽  
Gene Mutations ◽  
Azole Resistance ◽  
Wild Type ◽  
Environmental Isolates ◽  
Content Type ◽  
The Past ◽  
Agar Plug ◽  
Very High

ABSTRACT The past decade has seen an increase in aspergillosis in humans and animals due to Aspergillus viridinutans species complex members. Azole resistance is common to these infections, carrying a poor prognosis. cyp51A gene mutations are the main cause of acquired azole resistance in Aspergillus fumigatus. This study aimed to determine if the azole-resistant phenotype in A. viridinutans complex members is associated with cyp51A mutations or extrolite profiles. The cyp51A gene of clinical and environmental isolates was amplified using novel primers, antifungal susceptibility was tested using the Clinical and Laboratory Standards Institute methodology, and extrolite profiling was performed using agar plug extraction. Very high azole MICs were detected in 84% of the isolates (31/37). The MICs of the newer antifungals luliconazole and olorofim (F901318) were low for all isolates. cyp51A sequences revealed 113 nonsynonymous mutations compared to the sequence of wild-type A. fumigatus. M172A/V and D255G, previously associated with A. fumigatus azole resistance, were common among all isolates but were not correlated with azole MICs. Two environmental isolates with nonsusceptibility to itraconazole and high MICs of voriconazole and isavuconazole harbored G138C, previously associated with azole-resistant A. fumigatus. Some novel mutations were identified only among isolates with high azole MICs. However, cyp51A homology modeling did not cause a significant protein structure change for these mutations. There was no correlation between extrolite patterns and susceptibility. For A. viridinutans complex isolates, cyp51A mutations and the extrolites that they produced were not major causes of antifungal resistance. Luliconazole and olorofim show promise for treating azole-resistant infections caused by these cryptic species.

scholarly journals Cryptic Species and Azole Resistance in the Aspergillus niger Complex

2011 ◽  
Vol 55 (10) ◽  
pp. 4802-4809 ◽  
Author(s):  
Susan J. Howard ◽  
Elizabeth Harrison ◽  
Paul Bowyer ◽  
Janos Varga ◽  
David W. Denning
Keyword(s):  
Aspergillus Niger ◽  
Cryptic Species ◽  
Phylogenetic Trees ◽  
Antifungal Susceptibility ◽  
Clinical Isolates ◽  
Cross Resistance ◽  
Azole Resistance ◽  
Beta Tubulin ◽  
Data Set ◽  
Content Type

ABSTRACTAspergillus nigeris a common clinical isolate. Multiple species comprise theAspergillussectionNigriand are separable using sequence data. The antifungal susceptibility of these cryptic species is not known. We determined the azole MICs of 50 black aspergilli, 45 from clinical specimens, using modified EUCAST (mEUCAST) and Etest methods. Phylogenetic trees were prepared using the internal transcribed spacer, beta-tubulin, and calmodulin sequences to identify strains to species level and the results were compared with those obtained withcyp51Asequences. We attempted to correlatecyp51Amutations with azole resistance. Etest MICs were significantly different from mEUCAST MICs (P< 0.001), with geometric means of 0.77 and 2.79 mg/liter, respectively. Twenty-six of 50 (52%) isolates were itraconazole resistant by mEUCAST (MICs > 8 mg/liter), with limited cross-resistance to other azoles. Using combined beta-tubulin/calmodulin sequences, the 45 clinical isolates grouped into 5 clades,A. awamori(55.6%),A. tubingensis(17.8%),A. niger(13.3%),A. acidus(6.7%), and an unknown group (6.7%), none of which were morphologically distinguishable. Itraconazole resistance was found in 36% of the isolates in theA. awamorigroup, 90% of theA. tubingensisgroup, 33% of theA. nigergroup, 100% of theA. acidusgroup, and 67% of the unknown group. These data suggest thatcyp51Amutations in sectionNigrimay not play as important a role in azole resistance as inA. fumigatus, although some mutations (G427S, K97T) warrant further study. Numerous cryptic species are found in clinical isolates of theAspergillussectionNigriand are best reported as “A. nigercomplex” by clinical laboratories. Itraconazole resistance was common in this data set, but azole cross-resistance was unusual. The mechanism of resistance remains obscure.

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