Azole and fungicide resistance in clinical and environmental Aspergillus fumigatus isolates

Aspergillus fumigatus is a human pathogen but it is also a widespread filamentous fungus in the environment. A. fumigatus can therefore be exposed to antifungals used in medical and agricultural environments. Only the class of azoles is used in both of these environments (i.e., voriconazole and itraconazole in medicine; prochloraz, propiconazole or imazalil in agriculture). Exposure to azoles provides the potential for the development of resistance. Several clinical itraconazole-resistant isolates have been reported in A. fumigatus and their resistance mechanisms have been partially resolved. Since limited data exist on the susceptibility of A. fumigatus to both medical and agricultural antifungals, we undertook a drug susceptibility study including clinical (400) and agricultural (150) A. fumigatus isolates (Swiss origin). We tested azoles and also compounds of major antifungal classes used in agriculture (i.e., azoxystrobin, iprodione, benalaxyl or cyprodinil). The results showed that all A. fumigatus isolates were intrinsically resistant to iprodione, benalaxyl or cyprodinil (MIC90>32 µg.ml−1) and that azoxystrobin minimal inhibitory concentrations (MICs) showed a wide range (0.06 to 32 µg.ml−1). MIC ranges of azoles were compound-dependent. MIC90 for voriconazole, itraconazole, imazalil and prochloraz were within a range of 0.125 to 1 µg.ml−1 and similar between clinical and environmental isolates, whereas propiconazole was the least active compound (MIC90: 4-8 µg.ml−1). Ten clinical and 36 environmental isolates with high itraconazole MIC (≥2 µg.ml−1) were detected. In clinical isolates, no cross-resistance was observed between itraconazole and all others azoles tested. Several patterns of azole MICs for were, however, observed in the environmental isolates. Unexpectedly, a single environmental isolate was voriconazole-resistant (MIC of 16 µg.ml−1) but still susceptible to itraconazole (MIC of 2 µg.ml−1). Taken together, our results demonstrate the absence of susceptibility of A. fumigatus isolates to non-azole agricultural agents and that there is little impact of azole resistance in both clinical and environmental isolates. When detected, azole resistance was compound-specifi

Azole and fungicide resistance in clinical and environmental Aspergillus fumigatus isolates

Aspergillus fumigatus is a human pathogen but it is also a widespread filamentous fungus in the environment. A. fumigatus can therefore be exposed to antifungals used in medical and agricultural environments. Only the class of azoles is used in both of these environments (i.e. voriconazole and itraconazole in medicine; prochloraz, propiconazole or imazalil in agriculture). Exposure to azoles provides the potential for the development of resistance. Several clinical itraconazole-resistant isolates have been reported in A. fumigatus and their resistance mechanisms have been partially resolved. Since limited data exist on the susceptibility of A. fumigatus to both medical and agricultural antifungals, we undertook a drug susceptibility study including clinical (400) and agricultural (150) A. fumigatus isolates (Swiss origin). We tested azoles and also compounds of major antifungal classes used in agriculture (i.e. azoxystrobin, iprodione, benalaxyl or cyprodinil). The results showed that all A. fumigatus isolates were intrinsically resistant to iprodione, benalaxyl or cyprodinil (MIC90 > 32 microg x ml(-1)) and that azoxystrobin minimal inhibitory concentrations (MICs) showed a wide range (0.06 to 32 microg x ml(-1)). MIC ranges of azoles were compound-dependent. MIC90 for voriconazole, itraconazole, imazalil and prochloraz were within a range of 0.13 to 1 microg x ml(-1) and similar between clinical and environmental isolates, whereas propiconazole was the least active compound (MIC90: 4-8 microg x ml(-1)). Ten clinical and 36 environmental isolates with high itraconazole MIC ( > or = 2 microg x ml(-1)) were detected. In clinical isolates, no cross-resistance was observed between itraconazole and all others azoles tested. Several patterns of azole MICs were, however, observed in the environmental isolates. Unexpectedly, a single environmental isolate was voriconazole-resistant (MIC of 16 microg x ml(-1)) but still susceptible to itraconazole (MIC of 2 microg x ml(-1)). Taken together, our results demonstrate the absence of susceptibility of A. fumigatus isolates to non-azole agricultural agents and that there is little impact of azole resistance in both clinical and environmental isolates. When detected, azole resistance was compound-specific

Association between a specific Pneumocystis jiroveci dihydropteroate synthase mutation and failure of pyrimethamine/sulfadoxine prophylaxis in human immunodeficiency virus-positive and -negative patients

To investigate the possible association between different prophylactic sulfa drugs and the genotype of the Pneumocystis jiroveci dihydropteroate synthase (DHPS) gene, we examined DHPS polymorphisms in clinical specimens from 158 immunosuppressed patients (38 HIV-negative and 120 HIV-positive), using polymerase chain reaction-single-strand conformation polymorphism. Fifty-seven (36.1%) of 158 patients were infected with a mutant DHPS genotype. All patients who developed P. jiroveci pneumonia (PcP) while receiving pyrimethamine/sulfadoxine (PM/SD) prophylaxis (n=14) had a strain harboring DHPS with an amino acid change at position 57 (Pro-->Ser). This mutation was only present in 20 (14%) of 144 patients not receiving prophylaxis (P<.001). Hospitalization in a specific hospital was an independent risk factor for having P. jiroveci harboring the same DHPS mutation, which indirectly supports that interhuman transmission may affect the dissemination of the mutant strains

Mechanisms of antifungal resistance in the opportunistic fungus Aspergillus fumigatus

ABSTRACT Aspergillus fumigatus is one of the most prevalent airbone fungal pathogen and can cause severe fatal invasive aspergillosis in immunocompromised patients. Several antifungal agents are available to treat these infections but with limited success. These agents include polyenes (amphotericin B), echinocandins (caspofungin) and azoles, which constitute the most important class with itraconazole (ITC) and voriconazole as major active compounds. Azole-derived antifungal agents target the ergosterol biosynthesis pathway via the inhibition of the lanosterol 14α-demethylase (cyp51/ERG1 1), a cytochrome P450 responsible for the conversion of lanosterol to ergosterol, which is the main component of cell membrane in fungi. A. fumigatus is also found in the environment as a contaminant of rotting plant or present in composting of organic waste. Among antifungal agents used in the environment for crop protection, the class of azoles is also widely used with propiconazole or prochloraz as examples. However, other agents such as dicarboximide (iprodione), phenylamide (benalaxyl) or strobilurin (azoxystrobin) are also used. Emergence of clinical azole-resistant isolates has been described in several European countries. However the incidence of antifungal resistance has not been yet reported in details in Switzerland. In this study, the status of antifungal resistance was investigated on A. fumigatus isolates collected from Swiss hospitals and from different environmental sites and. tested for their susceptibility to several currently used antifungal agents. The data showed a low incidence of resistance for all tested agents among clinical and environmental isolates. Only two azole-resistant environmental isolates were detected and none among the clinical tested isolates. In general, A. fumigatus was susceptible to all antifungals tested in our study, except to azoxystrobin which was the less active agent against all isolates. Since mechanisms of antifungal resistance have been poorly investigated until now in A. fumigatus, this work was aimed 1) to identify A. fumigatus genes involved in antifungal resistance and 2) to test their involvement in the development of resistance in sampled isolates. Therefore, this work proposed to isolate A. fumigatus genes conferring resistance to a drug-hypersusceptible Saccharomyces cerevisiae strain due to a lack of multidrug transporter genes. Several genes were recovered including three distinct efflux transporters (atrF, atrH and mdrA) and a bZip transcription factor, yapA. The inactivation of each transporter in A. fumigatus indicated that the transporters were involved in the basal level of azole susceptibility. The inactivation of YapA led to a hypersusceptibility to H2O2, thus confirming the involvement of this gene in the oxidative stress response of A. fumigatus. The involvement of the abovementioned transporters genes and of other transporters genes identified by genome analysis in azole resistance was tested by probing their expression in some ITC-resistant isolates. Even if upregulation of some transporters genes was observed in some investigated isolates, the correlation between azole resistance and expression levels of all these transporters genes could not be clearly established for all tested isolates. Given these results, the present work addressed 1) alteration in the expression of cyp51A encoding for the azole target enzyme, and 2) mutation(s) in the cyp51A sequence as potential mechanisms of azote resistance in A. . However, overexpression of cyp51A in the investigated isolates was not linked with azote resistance. Since it was reported that mutation(s) in cyp51A were participating in azote resistance in A. fumigatus, a functional complementation of cyp51A cDNAs from ITC-resistant A. fumigatus strains in S. cerevisiae ergl 1 Δ mutant strain was attempted. Expression in S. cerevisiae allowed the testing of these cDNAs with regards to their functionality and involvement in resistance to specific azote compounds. We could demonstrate that Cyp51A protein with a G54E or M220K mutations conferred resistance to specific azoles in S. cerevisiae, therefore suggesting that these mutations were important for the development of azote resistance in A. fumigatus. In conclusion, this work showed a correlation between ITC resistance and mechanisms involving overexpression of transporters and cyp51A mutations in A. fumigatus isolates. However, azole resistance of some isolates has not been solved and thus it will be necessary to approach the study of resistance mechanisms in this fungal species using alternative methodologies. RESUME Aspergillus fumigatus est un champignon opportuniste répandu et est la cause d'aspergilloses invasives le plus souvent fatales chez des patients immunodéprimés. Plusieurs antifongiques sont disponibles afin de traiter ces infections, cependant avec un succès limité. Ces agents incluent les polyènes (amphotericin B), les échinocandines (caspofungin) et les azoles, qui représentent la plus importante classe d'antifongiques avec l'itraconazole (ITC) et le voriconazole comme principaux agents actifs. Les dérivés azolés ciblent la voie de biosynthèse de l'ergostérol via l'inhibition de la lanostérol 14α-demethylase (cyp51/ERG11), un cytochrome P450 impliqué dans la conversion du lanostérol en ergostérol, qui est un composant important de la membrane chez les champignons. A. fumigatus est également répandu dans l'environnement. Parmi les antifongiques employés en agriculture afin de protéger les cultures, les azoles sont aussi largement utilisés. Cependant, d'autres agents tels que les dicarboximides (iprodione), les phenylamides (benalaxyl) et les strobilurines (azoxystrobin) peuvent être également utilisés. L'émergence de souches cliniques résistantes aux azoles a été décrite dans différents pays européens. Cependant, l'incidence d'une telle résistance aux azoles n'a pas encore été reportée en détails en Suisse. Dans ce travail, l'émergence de la résistance aux antifongiques a été étudiée par analyse de souches d'A. fumigatus provenant de milieux hospitaliers en Suisse et de différents sites et leur susceptibilité testée envers plusieurs antifongiques couramment utilisés. Les données obtenues ont montré une faible incidence de la résistance parmi les souches cliniques et environnementales pour les agents testés. Seulement deux souches environnementales résistantes aux azoles ont été détectées et aucune parmi les souches cliniques. Les mécanismes de résistance aux antifongiques ayant été très peu étudiés jusqu'à présent chez A. fumigatus , ce travail a eu aussi pour but 1) d'identifier les gènes d' A. fumigatus impliqués dans la résistance aux antifongiques et 2) de tester leur implication dans la résistance de certaines souches. Ainsi, il a été proposé d'isoler les gènes d' A. fumigatus pouvant conférer une résistance aux antifongiques à une souche de Saccharomyces cerevisiae hypersensible aux antifongiques. Trois transporteurs à efflux (atrF, atrH et mdrA) et un facteur de transcription appartenant à la famille des bZip (YapA) ont ainsi été isolés. L'inactivation, dans une souche d'A. fumigatus, de chacun des ces transporteurs a permis de mettre en évidence leur implication dans la susceptibilité d'A. fumigatus aux antifongiques. L'inactivation de YapA a engendré une hypersusceptibilité à l' H2O2, confirmant ainsi le rôle de ce gène dans la réponse au stress oxydatif chez A . fumigatus. La participation dans la résistance aux antifongiques des gènes codant pour des transporteurs ainsi que d'autres gènes identifiés par analyse du génome a été déterminée en testant leur niveau d'expression dans des souches résistantes à l'ITC. Bien qu'une surexpression de transporteurs ait été observée dans certaines souches, une corrélation entre la résistance à l'ITC et les niveaux d'expression de ces transporteurs n'a pu être clairement établie. Ce présent travail s'est donc porté sur l'étude de 2 autres mécanismes potentiellement impliqués dans la résistance aux azoles : 1) la surexpression de cyp51A codant pour l'enzyme cible et 2) des mutations dans cyp51A. Cependant, la surexpression de cyp51A dans les souches étudiées n'a pas été constatée. L'effet des mutations de cyp51A dans la résistance aux azoles a été testée par complémentation fonctionnelle d'une souche S. cerevisiae déletée dans son gène ERG11. L'expression de ces gènes chez S. cerevisiae a permis de démontrer que les protéines Cyp51Ap contenant une mutation G54E ou M220K pouvaient conférer une résistance spécifique à certains azoles, ainsi suggérant que ces mutations pourraient être importantes dans le développement d'une résistance aux azoles chez A. fumigatus. En conclusion, ce travail a permis de mettre en évidence, dans des souches d'A. fumigatus , une corrélation entre leur résistance à l' ITC et les mécanismes impliquant une surexpression de transporteurs et des mutations dans cyp51A. Cependant, ces mécanismes n'ont pu expliquer la résistance aux azoles de certaines souches et c'est pourquoi de nouvelles approches doivent être envisagées afin d'étudier ces mécanismes

Identification of Aspergillus fumigatus multidrug transporter genes and their potential involvement in antifungal resistance.

Aspergillus fumigatus can cause severe fatal invasive aspergillosis in immunocompromised patients but is also found in the environment. A. fumigatus infections can be treated with antifungals agents among which azole and echinocandins. Resistance to the class of azoles has been reported not only from patient samples but also from environmental samples. Azole resistance mechanisms involve for most isolates alterations at the site of the azole target (cyp51A); however, a substantial number of isolates can also exhibit non-cyp51A-mediated mechanisms.We aimed here to identify novel A. fumigatus genes involved in azole resistance. For this purpose, we designed a functional complementation system of A. fumigatus cDNAs expressed in a Saccharomyces cerevisiae isolate lacking the ATP Binding Cassette (ABC) transporter PDR5 and that was therefore more azole-susceptible than the parent wild type. Several genes were recovered including two distinct ABC transporters (atrF, atrI) and a Major Facilitator transporter (mdrA), from which atrI (Afu3g07300) and mdrA (Afu1g13800) were not yet described. atrI mediated resistance to itraconazole and voriconazole, while atrF only to voriconazole in S. cerevisiae Gene inactivation of each transporter in A. fumigatus indicated that the transporters were involved in the basal level of azole susceptibility. The expression of the transporters was addressed in clinical and environmental isolates with several azole resistance profiles. Our results show that atrI and mdrA tended to be expressed at higher levels than atrF in normal growth conditions. atrF was upregulated in 2/4 of azole-resistant environmental isolates and was the only gene with a significant association between transporter expression and azole resistance. In conclusion, this work showed the potential of complementation to identify functional transporters. The identified transporters were suggested to participate in azole resistance of A. fumigatus; however, this hypothesis will need further approaches to be verified

Pneumocystis jiroveci Dihydropteroate Synthase Polymorphisms Confer Resistance to Sulfadoxine and Sulfanilamide in Saccharomyces cerevisiae

Failure of anti-Pneumocystis jiroveci prophylaxis with sulfa drugs is associated with mutations within the putative active site of the fungal dihydropteroate synthase (DHPS), an enzyme encoded by the multidomain FAS gene. This enzyme is involved in the essential biosynthesis of folic acid. The most frequent polymorphisms are two mutations leading to two amino acid changes ((55)Trp-Arg-(57)Pro to (55)Ala-Arg-(57)Ser), observed as a single or double mutation in the same P. jiroveci isolate. In the absence of a culture method for P. jiroveci, we studied potential resistance to sulfa drugs conferred by these polymorphisms by using Saccharomyces cerevisiae as a model. Single or double mutations identical to those observed in the DHPS domain of the P. jiroveci FAS gene were introduced by in vitro site-directed mutagenesis into alleles of the S. cerevisiae FOL1 gene, which is the orthologue of the P. jiroveci FAS gene. The mutated alleles were integrated at the genomic locus in S. cerevisiae and expressed by functional complementation in a strain with a disrupted FOL1 allele. The single mutation (55)Trp to (55)Ala conferred resistance to sulfanilamide, whereas the single mutation (57)Pro to (57)Ser conferred resistance to both sulfanilamide and sulfadoxine. Both single mutations also separately conferred hypersensitivity to sulfamethoxazole and dapsone. The resistance to sulfadoxine is consistent with epidemiological data on P. jiroveci. The double mutation (55)Trp-Arg-(57)Pro to (55)Ala-Arg-(57)Ser conferred on S. cerevisiae a requirement for p-aminobenzoate, suggesting reduced affinity of DHPS for this substrate. This characteristic is commonly observed in mutated DHPS enzymes conferring sulfa drug resistance from other organisms. However, the double mutation conferred hypersensitivity to sulfamethoxazole, which is not in agreement with epidemiological data on P. jiroveci. Taken together, our results suggest that the DHPS polymorphisms observed in P. jiroveci confer sulfa drug resistance on this pathogen

Evaluation of the ophthalmic and dermal irritability of the OLEOMASAJE formulation

Context: Ozonized vegetable oils present germicidal effects which can be used as active principle in different cosmetological compositions. The thematic about of the corporal massage advantage have been very treatment by aesthetics, dermatologic and consumers. OLEOMASAJE formulation content ozonized sunflower oil OLEOZON as active principle active which present moisturizer and conditioner effects. Aims: To determine the possible dermal and ophthalmic irritability effects of the OLEOMASAJE. Methods: The trial was conducted in rabbits and the techniques described in the standardized procedures of the work established by the Center of Biological Research and Evaluations from Pharmacy and Food Institute of Havana University were used according to Norma ISO 10993-10. The ethical principles of the Good Practices of Laboratory were fulfilled to avoid suffering to the animals during the experimentation. Male rabbits with body weight between 2.05 and 2.48 kg were used. In the skin and the ocular structures the effects were observed immediately after of the application at 1, 24, 48 and 72 hours. Draize´s scale was applied to evaluate skin and ocular structures lesions. Results: The OLEOMASAJE formulation does not irritate de skin of the assayed rabbits. However, the ocular structures irritability index was of 4.5 after of first hour to apply of product. These wounds were missing before of 24 hours to apply of product. Conclusions: The OLEOMASAJE formulation obeys the indispensable requirements for the acceptance as cosmetic product and for it is used in corporal massage

Sulfa resistance and dihydropteroate synthase mutants in recurrent Pneumocystis carinii pneumonia

Failure of sulfa or sulfone prophylaxis is associated with mutations in Pneumocystis carinii gene coding for dihydropteroate synthase (DHPS). The DHPS genotype was analyzed in AIDS patients who had two separate episodes of P. carinii pneumonia. The results suggest that DHPS mutations can be selected de novo within patients by the pressure of a sulfa or sulfone drug