Dissertations / Theses on the topic 'Antifungal drugs'

Pharmaceutical Sciences
Ph.D.
Onychomycosis is fungal infection of toe nails or fingernails caused by a fungal microbe that invades the nail bed. It is the most common disease of the nails and constitutes about a half of all nail abnormalities and may affect toenails or fingernails, but toenail infections are particularly common. It occurs in about 10 percent of the adult population. The most common symptoms of fungal nail infection are thickening and discoloration of the nail. Treatment of onychomycosis is challenging because the infection is embedded in the nail making it difficult for the drug to diffuse to the site of infection. Onychomycosis is an opportunistic infection in people with compromised immune function and in those with diabetes, psoriasis, HIV/AIDS etc. Onychomycosis affects patients’ physical and psychological health and has a negative impact on overall quality of life. Oral administration of antifungal agents has been the mainstay in treatment of onychomycosis such as griseofulvin, terbinafine and itraconazole, but has limitations of systemic adverse events and drug interactions, whereas several drugs have been approved for topical administration but their efficacy is limited by the low permeability of the nail plate. This study evaluated the preformulation transungual permeability of econazole nitrate and formulation development of a transungual topical patch utilizing penetration enhancers in combination with econazole nitrate to optimize the delivery and penetration through the nail. The objectives of this project were to: 1) determine the critical factors for the in vitro transungual delivery of econazole nitrate, 2) design and develop a transungual formulation containing econazole nitrate and selection of the penetration enhancers, and 3) characterize the physical characteristics and functional properties of a novel transungual formulation. There were ten penetration enhancers being screened in this project according to the enhancement for saturation solubility, in vitro nail penetration and in vitro skin permeation and penetration of the antifungal drug econazole nitrate. Unlike transdermal drug delivery, the selection requirements for skin penetration enhancer were to increase drug accumulation in the epidermis and decrease the amount in the dermis to avoid unnecessary systermic absorption (Palliyil, et al. 2013). Thiourea (TU) improved the solubility and nail penetration of econazole nitrate. It also produced enhancement in the transungual diffusion of the drug. It was selected as the nail permeation enhancer and skin penetration enhancer for econazole nitrate. In the pH study, pH 5 ammonium phosphate buffer was the most effective pH for both enhancing the amount of drug in the nail and decreasing keratin binding. This resulted in increased accumulated of free drug in the target nail. In the formulation screening study, pressure sensitive adhesives (PSA), polyisobutylene, polysiloxane and polyacrylate classes of adhesives, were screened to develop a monolithic drug-in-adhesive type nail patch. Increasing the concentration of TU from 1% to 2.5% resulted in drug crystallization in the dry patch, therefore the concentration of 1% (w/w) TU was selected for all further screening. The concentration of econazole nitrate, propylene glycol and triethyl citrate were screened at 2.5%, 10% and 10% accordingly to ensure high drug release rate with no drug crystallization. The in vitro drug release rate of EN from the patch was improved with propylene glycol and hydrophobic plasticizer triethyl citrate. Polyvinylpyrrolidone was added to the patch formulation to lower the pH of the patch. This resulted in a greater concentration of ionized EN. The nail permeation and penetration of EN were studied in vitro using human cadaver toenails mounted in Franz diffusion cells. Thiourea, when formulated in the novel nail patch, was shown to deliver higher amount of EN into target tissues with a shorter permeation lag time compared to formulations which did not utilize thiourea.
Temple University--Theses

The continuous emergence of drug-resistance pathogens is a global concern. As a result, substantial effort is being expended to develop new therapeutics and mechanisms for controlling microbial growth to avoid entering a "post-antibiotic" era in which commonly used antibiotics are no longer effective in treating infections. In this work, we investigate the efficacy and application of ceragenins as non-peptide mimics of antimicrobial peptides (AMPs). First, this work examines the susceptibility of drug-resistant Gram-negative bacteria. The susceptibility of colistin-resistant clinical isolates of Klebsiella pneumoniae to ceragenins and AMPs suggests that there is little to no cross-resistance between colistin and ceragenins/AMPs. Furthermore, Lipid A modifications are found in bacteria with modest changes in susceptibility to ceragenins and with high levels of resistance to colistin. Next, we investigated the potential for cross resistance between chlorhexidine, colistin, AMPs and ceragenins as repeated exposure of bacteria to chlorhexidine might result in cross resistance with colistin, AMPs or ceragenins. Furthermore, a proteomics study on the chlorhexidine-resistant strains showed that chlorhexidine resistance is associated with upregulation of proteins involved in the assembly of LPS for outer membrane biogenesis and virulence factors in Pseudomonas aeruginosa.Second, this dissertation describes the antifungal activity of ceragenins against an emerging multidrug-resistant fungus, Candida auris. We found that lead ceragenins displayed activities comparable to known antifungal agents against C. auris isolates. We also found that fungal cell morphology was altered in response to ceragenin treatment, that ceragenins exhibited activity against sessile organisms in biofilms, and that gel and cream formulations including CSA-44 and CSA-131 resulted in a significant log reduction against established fungal infections in ex vivo mucosal tissues. Finally, a hydrogel film containing CSA-131 was generated on endotracheal tubes (ETTs). ETTs provide an abiotic surface on which bacteria and fungi form biofilms that cause serious infections. In this study, the eluting ceragenin prevented fungal and bacterial colonization of coated ETTs for extended periods while uncoated tubes were colonized by bacteria and fungi. Coated tubes were well tolerated in intubated pigs. The ability of ceragenins to eradicate established biofilms make them attractive potential therapeutics for persistent infections in the lung, including those associated with cystic fibrosis. In ex vivo studies, we initially found that this ceragenin, at concentrations necessary to eradicate established biofilms, also causes loss of cilia function. However, by formulating CSA-131 in poloxamer micelles, cilia damage was eliminated and antimicrobial activity was unaffected. These findings suggest that CSA-131, formulated in micelles, may act as a potential therapeutic for polymicrobial and biofilm-related infections in the lung and trachea.

In Saccharomyces cerevisiae, zinc cluster proteins constitute the major family of transcriptional regulators for a variety of metabolic processes, yet the function of many are currently unknown. Previous studies have characterized Rds2 as a zinc cluster transcription factor that plays a role in antifungal drug resistance, but an exact mechanism is undefined. However, it has been established that Rds2 is a major regulator of gluconeogenesis. In this study, we aim to further mechanistically characterize the role of Rds2 in antifungal drug resistance. Microarray-based expression profiling of both wild type and ∆rds2 strains treated with ketoconazole indicates a greater than 2-fold decreased expression of genes involved in gluconeogenesis and the glyoxylate cycle, such as PCK1, YIG1, and MLS1, in cells lacking Rds2. Quantitative real-time polymerase chain reaction (qPCR) confirmed our microarray data. Furthermore, deletion of these metabolic genes confers azole hypersensitivity. Our preliminary results show that Rds2's role as a regulator of gluconeogenesis and the glyoxylate cycle is linked to its role in antifungal drug resistance.
Les protéines à grappes de zinc constituent le groupe principal de régulateurs de la transcription pour plusieurs processus métaboliques chez la levure Saccharomyces cerevisiae. La fonction de plusieurs de ces protéines reste pourtant inconnue. Plusieurs études ont démontré que la protéine à grappe de zinc Rds2 joue un rôle dans la résistance aux médicaments antifongiques, mais la mécanisme exact reste indéfini. Par contre, il a été clairement démontré que Rds2 est un important régulateur de la gluconéogénèse. Dans cette étude, nous voulons définir davantage la mécanisme de Rds2 dans la résistance aux médicaments antifongiques. Une analyse d'expression par micropuces d'ADN de la souche sauvage et de la souche ∆rds2 exposées au kétoconazole a démontré chez la souche ∆rds2 un niveau d'expression deux fois plus bas des gènes impliqués dans la gluconéogénèse et dans le cycle du glyoxylate, tels que PCK1, YIG1 et MLS1. Une analyse par PCR quantitatif a confirmé les résultats des micropuces d'ADN. De plus, la déletion de ces gènes métaboliques cause une hypersensibilité à l'azole. Nos résultats préliminaires montrent que la fonction de Rds2 en tant que régulateur de la gluconéogénèse et du cycle du glyoxylate est lié à sa fonction dans la résistance aux médicaments antifongiques.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Diversos sÃo os relatos de resistÃncia in vitro de cepas de Candida spp. a fÃrmacos antifÃngicos, em especial a derivados azÃlicos. Deste modo, a prospecÃÃo de novos compostos com propriedade antifÃngica se faz necessÃria. Assim, o objetivo deste estudo foi avaliar a atividade antifÃngica do sesquiterpeno farnesol, sua aÃÃo sinÃrgica com antifÃngicos fluconazol (FLC), itraconazol (ITC), voriconazol (VRZ), anfotericina B (AMB) e caspofungina (CASP), bem como avaliar sua aÃÃo sob a atividade enzimÃtica de fosfolipases e proteases, consideradas importantes fatores de virulÃncia em Candida spp. Para tanto, foram avaliadas cepas de C. albicans (n=23), C. parapsilosis (n=16) e C. tropicalis (n=6). A concentraÃÃo inibitÃria mÃnima (CIM) foi determinada por meio da tÃcnica de microdiluiÃÃo, preconizada pelo Clinical Laboratory Standards Institute (CLSI). Em adiÃÃo, foi investigado o efeito do farnesol sobre a atividade de fosfolipase utilizando Ãgar Sabouraud suplementado com gema de ovo e a atividade de protease por tÃcnica espetrofotomÃtica. Paralelamente 14 cepas escolhidas aleatoriamente, foram prÃ-incubadas em trÃs concentraÃÃes sub-CIM de farnesol, afim de avaliar se o farnesol era capaz de causar algum dano na sensibilidade da cepa. Para as 45 cepas avaliadas, os valores de CIM para farnesol variaram de 9,37 a 150 ÂM para Candida spp. Para os derivados azÃlicos, o intervalo dos valores de CIM para fluconazol foi de 0,03125 a > 64 Âg/ml, observando-se a presenÃa de 18 cepas resistentes (CIM > 64 Âg/mL). Em relaÃÃo ao itraconazol, os valores de CIM variaram de 0,03125 a >16 Âg/mL e 35 cepas apresentaram resistÃncia a esse antifÃngico (CIM ≥1 Âg/mL). Constatou-se que das 45 cepas em estudo, 19 apresentaram resistÃncia a anfotericina B, com CIM > 1 Âg/mL. Quanto a caspofungina, os valores de CIM variaram de 0,0625 a 2 Âg/mL, com apenas seis cepas exibido resistÃncia, com CIM de 2 Âg/mL. A combinaÃÃo anfotericina B e farnesol apresentou sinergismo em 94,7% (18/19) das cepas de Candida spp. resistentes, evidenciado pelos valores de FICI ≤ 0,5. Na associaÃÃo fluconazol e farnesol, observou-se uma interaÃÃo sinÃrgica frente a todas as cepas de Candida spp. avaliadas, apresentando FICI ≤ 0,5. Trinta e seis cepas (18 C. albicans, 12 C. parapsilosis e 6 C. tropicalis) foram testadas frente à associaÃÃo de itraconazol e farnesol, observando a ocorrÃncia de sinergismo (FICI ≤ 0,5) em 94,4% dos isolados. Quanto à caspofungina todas as cepas testadas (C. parapsilosis, n=4; C. albicans, n=2) tiveram FICI ≤ 0,5, caracterizando associaÃÃo sinÃrgica com o farnesol. ApÃs constataÃÃo de que 17 das 45 cepas expressavam a enzima fosfolipase, as mesmas foram incubadas em concentraÃÃes sub-CIM de farnesol, por 24 horas, quando observouâse uma medida de Pz mÃdia de 0,73 para as cepas testadas sem contato com farnesol e valores de 0,71, 0,61, e 0,54 para aquelas incubadas em doses sub-inibitÃria de farnesol. Em relaÃÃo à produÃÃo de protease, observou-se que todas as 14 cepas produziam a enzima, em baixas concentraÃÃes, variando de 0,002 a 0,02 U/mL, e que a prÃ-incubaÃÃo com farnesol nÃo interferiu na produÃÃo enzimÃtica. No tocante a prÃ-incubaÃÃo das cepas com farnesol constatou-se que o mesmo interferi direta e indiretamente no fenÃmeno de resistÃncia das cepas. Estes resultados demonstram, em especial, o efeito do composto farnesol sobre a sensibilidade antifÃngica de Candida spp., abrindo a perspectiva de novos estudos com o intuito de determinar os mecanismos de aÃÃo desses compostos no metabolismo celular dos fungos.
There are several reports of in vitro resistance to antifungal drugs, especially azole derivatives, in strains of Candida spp. For this reason, the pursuit for new compounds that present antifungal properties is necessary. Thus, this study aimed at evaluating the antifungal activity of farnesol and its interaction with classical antifungal drugs against Candida spp., as well as evaluating its effect on the production of phospholipase and protease, which are important virulence factors for Candida species. Fourty-five strains of Candida spp. (23 C. albicans, 16 C. parapsilosis and 6 C. tropicalis) were tested through broth microdilution as described by the Clinical Laboratory Standards Institute (CLSI), document M27A2, and the minimum inhibitory concentrations (MICs) for amphotericin B (AMB), fluconazole (FLC), itraconazole (ITC), caspofungin (CAS) and farnesol (FAR) were individually determined. In addition, the effect of FAR on phospholipase activity was assessed by growing the strains on 2% Sabouraud agar, supplemented with egg yolk, and protease activity was determined through spectrophotometry. Then, 13 strains were randomly chosen, pre-incubated at three sub-inhibitory concentrations of FAR for 24 hours and re-submitted to microdilution assay. For the 45 evaluated Candida spp. strains the MIC values for FAR varied from 9.37 to 150 ÂM. For the classical antifungal drugs, MICs ranged from 0.0625 to 4 Âg/mL for AMB, with 19 resistant strains (MIC>1 Âg/mL); from 0.0125 to >64 for FLC, with 18 resistant strains (MIC> 64 Âg/mL); from 0.03125 to >16 Âg/mL for ITC, with 35 resistant strains (MIC ≥1 Âg/mL), and from 0.0625 to 2 Âg/mL for CAS, with six resistant strains (MIC≥2 Âg/mL). All resistant strains were tested against the combination of FAR with the drug to which they presented resistance. The combination of AMB and FAR was synergistic against 94.7% (18/19) of the Candida spp. isolates, as shown through the obtention of FICI≤0.5. FAR and FLC interacted synergistically against all tested strains (n=18), exhibiting FICI values of ≤0.5. The combination of FAR and ITC presented synergistic interactions (FICI≤0.5) against 94.4% of the tested isolates (33/35). Finally, FAR and CAS showed to interact synergistically (FICI≤0.5) against all tested strains. Concerning virulence factors, it was observed that 17/45 isolates produced phospholipase, with a mean Pz of 0.71. After incubating these strains at three different concentrations of FAR the mean Pz values of 0.71, 0.61 and 0.54 were obtained, after incubation at the lowest, the intermediate and the highest concentrations of FAR, respectively. In addition, it was observed that the 14 randomly chosen strains that were screened for protease activity produced low concentrations of these enzymes, varying from 0.002 to 0.02 U/mL and that FAR presented no effect on enzymatic production. Finally, it was observed that pre-incubating strains at the highest sub-inhibitory concentration of FAR reduced the MIC range of the tested antifungal drugs. These results especially show the effects of FAR on the susceptibility of Candida species to classical antifungal drugs, providing perspectives for the development of researches on the mechanisms of this compound on fungal cell metabolism

 

One of the most common HIV-associated opportunistic infections is candidiasis, caused by Candida albicans or other Candida species. In immune suppressed subjects, this commensal organism can cause an increase in patient morbidity and mortality due to oropharyngeal or systemic dissemination. Limited information exists on the prevalence and antifungal susceptibility of Candida species in the African continent, the most HIV-affected region globally and home to new and emerging drug resistant Candida species. The mechanisms of Candida drug resistance in the African continent have also not been described. In this study, 255 Candida species isolated from the oral mucosa of HIV-positive South African and Cameroonian patients were identified using differential and chromogenic media and their drug susceptibility profiles tested using the disk diffusion method and the TREK Sensititre system, an automated broth microdilution method. Candida cell wall fractions were run on SDSPAGE and HPLC-MS with the aim of identifying peptides specifically expressed by antifungal drug resistant isolates. Comparisons between the two groups of isolates revealed differences in Candida species prevalence and drug susceptibility with interesting associations observed between specific drug resistance and duration of ARV therapy. This study showed that fluconazole, the drug of choice for the treatment of candidiasis in the African continent, is not an effective therapy for most cases of Candida infection, and suggests that regional surveillance be implemented in the continent. A multiple-drug resistant Candida strain was identified in this study, a finding that has not previously been documented. The use of proteomics tools allowed for the identification of peptides involved in drug resistance and the elucidation of Candida colonization mechanisms in HIV-infected African patients.

This project was set out to broaden our knowledge of the processes driving the emergence of antifungal drug resistance in an opportunistic yeast pathogen Candida glabrata. More precisely, we sought to find the mutational signatures of drug resistance and cross-resistance to representatives of two clinically important antifungal drug classes, azoles and echinocandins. By combining in vitro evolution with phenotypic screening and comparative genomics analysis we investigated the relationship between genomic changes, fitness and drug susceptibility to shed light on the cellular mechanisms and evolutionary constraints of antifungal drug resistance in this important pathogen

Introducció. Les concentracions plasmàtiques (CP) de voriconazole (VCZ) tenen una elevada variabilitat. El 2012 va canviar la posologia del VCZ a pediatria. Existeixen poques dades pediàtriques sobre el monitoratge de CP (MCP) de VCZ amb la dosificació actual. Es pretén avaluar el MCP i descriure la seva relació amb l’efectivitat i seguretat del tractament de la infecció fúngica invasiva (IFI) a pediatria amb la nova posologia. Mètodes. Estudi prospectiu observacional unicèntric, realitzat des de gener de 2014 fins agost de 2018 amb pacients de 2-12 anys en tractament amb VCZ a les dosis actuals, amb MCP setmanal i una pauta de canvi de dosi en funció del valor de les CP. Es categoritza la IFI com a provada/probable/possible segons els criteris diagnòstics del grup EORTC/MSG i s’avalua la resposta al tractament segons els criteris del mateix grup. Els efectes adversos (EA) es classifiquen mitjançant la taula americana Common Terminology Criteria for Adverse Events. Es registren també altres factors que poden afectar les CP. Resultats. S’han obtingut 229 CP de 28 episodis d’IFI (18 IFI provada/probable). La durada del tractament entre els episodis d’IFI provada/probable ha estat de 83,5 dies (5-896). El 64,2% de les CP van ser terapèutiques (1-5,5 mg/L), el 27,5% infraterapèutiques i el 8,3% supraterapèutiques. La pauta de modificació de dosi quan les CP estaven fora del rang terapèutic ha aconseguit corregir el 75% dels valors quan s’ha seguit correctament el protocol. La primera setmana de tractament hi ha hagut més CP infraterapèutiques (43,5%) que la resta del període (25,9%) (p=0,07). La dosi mitjana per a aconseguir unes CP terapèutiques en pacients de 2-7 anys (21 mg/kg/dia) ha estat més alta que en pacients més grans (p=0,02) i que la recomanada actualment. En pacients de 2-7 anys s’ha objectivat una relació lineal entre la dosi i el valor de les CP (p=0,01). La hipoalbuminèmia greu (p=0,02) i l’elevació de la proteïna C reactiva (CRP) (p=0,03) s’han associat a un pitjor control de les CP. L’efectivitat del tractament ha estat del 60% en l’avaluació precoç i del 53,3% en l’avaluació tardana. La supervivència als 6 mesos ha estat del 80%, sense èxitus atribuïts a la IFI. Les alteracions hepàtiques han estat l’EA més freqüent (88,9% dels pacients), majoritàriament de baix grau. Els EA visuals, neurològics, gastrointestinals, cutanis o renals s’han produït en menor freqüència (<10%). L’adequació de les CP s’ha associat amb major efectivitat del tractament en l’avaluació tardana (p=0,03). Les CP >5,5 mg/L s’han relacionat amb alteracions hepàtiques (p=0,02) i renals (p=0,03). Conclusions. La variabilitat de les CP de VCZ amb la nova posologia és encara elevada i es veu influïda pel valor de l’albúmina i de la CRP, relacionades amb la inflamació sistèmica. La dosi necessària per a aconseguir unes CP correctes en pacients de 2-7 anys és superior a la recomanada. La pauta de modificació de dosi proposada al nostre treball sembla ser efectiva. El tractament amb la nova posologia és efectiu i segur, però les alteracions dels enzims hepàtics són freqüents. Les CP de VCZ es relacionen amb l’efectivitat i la seguretat del tractament amb la nova posologia. Cal continuar realitzant el MCP de VCZ i plantejar-se la necessitat d’augmentar la dosi de VCZ en els pacients més petits, de protocol·litzar el canvi de dosi en funció del valor de les CP i de realitzar un control estricte de la inflamació sistèmica.
Introducción. Las concentraciones plasmáticas (CP) de voriconazole (VCZ) tienen una elevada variabilidad. El 2012 cambió la posología del VCZ en pediatría. Existen pocos datos pediátricos sobre la monitorización de CP (MCP) de VCZ con la dosificación actual. Se pretende evaluar la MCP y describir su relación con la efectividad y seguridad del tratamiento de la infección fúngica invasiva (IFI) en pediatría con la nueva posología. Métodos. Estudio prospectivo observacional, realizado en un solo centro desde enero de 2014 hasta agosto de 2018 con pacientes de 2-12 años en tratamiento con VCZ a las dosis actuales, con MCP semanal y una pauta de cambio de dosis en función del valor de las CP. Se categoriza la IFI como probada/probable/posible según los criterios diagnósticos del grupo EORTC/MSG y se evalúa la respuesta al tratamiento según los criterios del mismo grupo. Los efectos adversos (EA) se clasifican mediante la tabla americana Common Terminology Criteria for Adverse Events. Se registran también otros factores que pueden afectar las CP. Resultados. Se han obtenido 229 CP de 28 episodios de IFI (18 IFI probada/probable). La duración del tratamiento entre los episodios de IFI probada/probable ha sido de 83,5 días (5-896). El 64,2% de las CP fueron terapéuticas (1-5,5 mg/L), el 27,5% infraterapéuticas y el 8,3% supraterapéuticas. La pauta de modificación de dosis cuando las CP estaban fuera del rango terapéutico ha logrado corregir el 75% de los valores cuando se ha seguido correctamente el protocolo. La primera semana de tratamiento ha habido más CP infraterapéuticas (43,5%) que el resto del periodo (25,9%) (p=0,07). La dosis media para conseguir unas CP terapéuticas en pacientes de 2-7 años (21 mg/kg/día) ha sido más alta que en pacientes más mayores (p=0,02) y que la recomendada actualmente. En pacientes de 2-7 años se ha objetivado una relación lineal entre la dosis y el valor de las CP (p=0,01). La hipoalbuminemia grave (p=0,02) y la elevación de la proteína C reactiva (CRP) (p=0,03) se han asociado a un peor control de las CP. La efectividad del tratamiento fue del 60% en la evaluación precoz y del 53,3% en la evaluación tardía. La supervivencia a los 6 meses fue del 80%, sin fallecimientos atribuidos a la IFI. Las alteraciones hepáticas han sido el EA más frecuente (88,9% de los pacientes), en su mayoría de escasa gravedad. Los EA visuales, neurológicos, gastrointestinales, cutáneos o renales se han producido con menor frecuencia (<10%). La adecuación de las CP se ha asociado a mayor efectividad del tratamiento en la evaluación tardía (p=0,03). Las CP >5,5 mg/L se han relacionado con alteraciones hepáticas (p=0,02) y renales (p=0,03). Conclusiones. La variabilidad de las CP de VCZ con la nueva posología es todavía elevada y se ve influida por el valor de la albúmina y de la CRP, relacionadas con la inflamación sistémica. La dosis necesaria para conseguir unas CP correctas en pacientes de 2-7 años es superior a la recomendada. La pauta de modificación de dosis propuesta en nuestro estudio parece ser efectiva. El tratamiento con la nueva posología es efectivo y seguro, pero las alteraciones en las enzimas hepáticas son frecuentes. Las CP de VCZ se relacionan con la efectividad y la seguridad del tratamiento con la nueva posología. Hay que seguir realizando el MCP de VCZ y plantearse la necesidad de aumentar la dosis de VCZ en los pacientes más pequeños, de protocolizar el cambio de dosis en función del valor de las CP y de realizar un control más estricto de la inflamación sistémica.
Background. It is known that voriconazole (VCZ) plasma levels (PL) are highly variable. Dose recommendation changed in 2012 for paediatric patients between 2 and 12 years old (yo). Little data on therapeutic drug monitoring (TDM) after these new recommendations is available. We aim to evaluate TDM of VCZ in paediatric patients with invasive fungal infection (IFI) and its relationship with safety and effectiveness. Methods. Prospective observational single-centre study from January 2014 to August 2018. All consecutive patients aged 2-12 yo receiving VCZ were included. TDM was performed weekly and doses were changed according to local protocol. IFI were categorized as possible/probable/proven according to EORTC/MSG group criteria, response to treatment was evaluated according to same group criteria and adverse events were recorded following the Common Terminology Criteria for Adverse Events. Factors potentially influencing PL were analysed. Results. We obtained 229 PL from 28 IFI episodes (18 probable/proven). Duration of treatment in proven/probable episodes was 83.5 days (5-896). 64.2% of PL were therapeutic (1-5.5 mg/L), but more than one-third of them weren’t: 27.5% below; 8.3% above. After dose modification according with our protocol, 75% therapeutic PL were achieved. In the first week of treatment there were more infratherapeutic PL (43.5%) than the rest of the period (25.9%) (p=0.07). Dose to achieve therapeutic PL in patients below 8 yo (21mg/kg/day) was higher than recommended and higher than in older patients. In these patients, a linear relationship between dose and PL value was observed (p=0.01). Severe hypoalbuminemia (p=0,02) and marked elevation of C-reactive protein (CRP) (p=0,03) were associated with worse PL adequacy. The effectiveness of treatment was 60% in the early evaluation and 53.3% in the late evaluation. Survival at 6 months was 80%, with no deaths attributed to IFI. Non-infratherapeutic PL were associated with better treatment response at late evaluation, and supratherapeutic PL were associated with liver (p=0,02) and renal dysfunction (p=0,03). Conclusions. VCZ PL variability remains high despite current updated recommendations and it’s influenced by severe hypoalbuminemia and increased CRP. Therefore, additional efforts to control inflammation in children with IFI should be encouraged. Our dose modification recommendation appears to be effective. Treatment with the new dosage is effective and safe, but alterations in liver enzymes are common. Therapeutic VCZ PL are related to treatment effectiveness and safety; thus, TDM of VCZ is mandatory. Higher doses should be considered in patients below 8 yo. It’s necessary to consider protocolizing the dose modification based on the value of the PL.

INTRODUÇÃO: A frequência de Candida parapsilosistem apresentado considerável aumento em UTIs neonatais. Embora a taxa de resistência dessa espécie aos azólicos seja baixa, recentemente têm sido relatados surtos de candidemia por isolados resistentes. A capacidade de adesão e formação de biofilme por essa espécie confere maior potencial patogênico e resistência aos antifúngicos. Portanto, a vigilância epidemiológica, tanto da resistência aos antifúngicos como da virulência dos isolados, é fundamental para o controle e prevenção das infecções e surtoshospitalares. A técnica de MALDI-TOF MS pode ser uma ferramenta útil para realizar análises proteômicas das células planctônicas e sésseis de Candida parapsilosis,e identificar possíveis alvos terapêuticos ou biomarcadores, específicos do biofilme. MÉTODOS: Isolados clínicos do complexo Candida parapsilosis de dois hospitais universitários públicos brasileiros, foram submetidos à identificação por RAPD, RFLP e MALDI-TOF MS e aos testes de suscetibilidade aos antifúngicos. Ensaios de formação de biofilme foram realizados para quantificar a biomassa, a atividade metabólica e ainda, avaliar atividade in vitrodos antifúngicos contra as células sésseis dos isolados com alta formação de biofilme. A análise proteômica por MALDI-TOF MS das células planctônicas e sésseis dos isolados com alta formação de biofilme, foi realizada nas plataformas VITEK-MS(TM) e Microflex(TM). Isolados de Candida parapsilosis (sensu stricto) foram genotipados por PFGE e análise de microssatélites. Os genótipos foram correlacionados com dadosclínicos, para investigar a ocorrência de um surto em CTI adulto, e as sequências do gene ERG11dos isolados não suscetíveis aos azólicos (NSA) foram analisadas. RESULTADOS: Foram obtidos 38 isolados do complexo Candida parapsilosis, sendo Candida parapsilosis(sensu stricto) a espécie de maior frequência, superando 80% em ambos os hospitais, seguida de C. orthopsilosis e C. metapsilosis. Embora todos os isolados tenham sido suscetíveis à anfotericina B ( < 2 mg/L) e apresentado suscetibilidade intermediária à anidulafungina, caspofungina e micafungina ( > 0,002 mg/L), elevada frequência de não suscetibilidade (resistência ou suscetibilidade intermediária) ao fluconazol e voriconazol foi observada entre isolados de um dos hospitais. Alta formação de biofilme foi observada apenas entre os isolados da espécie Candida parapsilosis(sensu stricto). Por outro lado, a maioria dos isolados NSA, apresentou baixa formação de biofilme e baixa atividade metabólica. Apenas anfotericina B apresentou atividade contra os biofilmes de Candida parapsilosis. As duas plataformas de MALDI-TOF MS conseguiram diferenciar os perfis proteômicos das células planctônicas e sésseis dos isolados. A genotipagem de Candida parapsilosis(sensu stricto) revelou a persistência de isolados clonais NSA e a mutação A395T no gene ERG11foi identificada exclusivamente entre os isolados resistentes ao azólicos. O uso de corticosteroide foi associado, estatisticamente, com a ocorrência de isolados clonais NSA. CONCLUSÕES: Candida parapsilosis (sensu stricto) se mantém como a principal espécie do complexo em infecções sanguíneas. Isolados resistentes aos azólicos, com mutações no gene ERG11, ocorreram nos dois hospitais avaliados. A correlação dos genótipos com os dados clínicos evidenciou a ocorrência de um surto envolvendo isolados clonais NSA, com associação estatisticamente significativa, ao uso prévio de corticosteroides. Candida parapsilosis (sensu stricto) foi a única espécie que apresentou alta formação de biofilme, o qual demonstrou elevada resistência às equinocandinas. As duas plataformas de MALDI-TOF MS, diferenciaram os perfis proteômicos, das células planctônicas e sésseis de Candida parapsilosis, demonstrando o potencial emprego dessa tecnologia na identificação de possíveis alvos terapêuticos ou biomarcadores, específicos de biofilmes
INTRODUCTION: The frequency of Candida parapsilosis isolates has increased considerably in neonatal ICUs. Although resistance to azoles is usually low in this species, candidemia outbreaks by resistant isolates have been recently reported. Theability of adhesion and biofilm formation by this species confers higher pathogenic potential and resistance to antifungal agents. Therefore, establishment of profiles of antifungal susceptibility and virulence, besides the epidemiological surveillance ofC. parapsilosisisolates are essential for the control and prevention of nosocomial infections and outbreaks. The MALDI-TOF MS technique can be a useful tool to perform proteomic analyzes of the planktonic and sessile cells of Candida parapsilosis, identifying possible biofilm-specific therapeutic targets or biomarkers. METHODS: Candida parapsilosisclinical isolates from two Brazilian public university hospitals were identified by RAPD, RFLP and MALDI-TOF MS and submitted to antifungal susceptibility tests. Biofilm formation assays were carried out to quantify the biomass and metabolic activity, and to evaluate the in vitroactivity of antifungal drugs against the sessile cells of the isolates with high biofilm formation. Proteomic analysis of the planktonic and sessile cells of the isolates with high biofilm formation was performed in two MALDI-TOF MS platforms, VITEK-MS(TM) and Microflex(TM). Candida parapsilosis(sensu stricto) isolates were genotyped by PFGE and microsatellite analysis. The genotypes were correlated with clinical data to investigate the occurrence of an outbreak in the adult ICU andERG11gene sequences from non-susceptible to azoles (NSA) isolates were also analyzed. RESULTS: 38 clinical isolates of the Candida parapsilosiscomplex were obtained, with Candida parapsilosis(sensu stricto) being the most frequent species (exceeding 80% in both hospitals), followed by C. orthopsilosisand C. metapsilosis. Although all isolates were susceptible to amphotericin B ( < 2 mg/L) and showed intermediate susceptibility to anidulafungin, caspofungin e micafungin ( > 0,002 mg/L), high frequency of non-susceptibility (resistance or intermediate susceptibility) to fluconazole and voriconazole was observed among isolates from one of the hospitals. High biofilm formation was only observed among isolates of the Candida parapsilosis. (sensu stricto) species. On the other hand, most of the NSA isolates presented low biofilm formation and low metabolic activity. Only amphotericin B showed activity against Candida parapsilosisbiofilms. The two MALDI-TOF MS platforms were able to differentiate the proteomic profiles of planktonic and sessile cells of isolates. Candida parapsilosis(sensu stricto) genotyping revealed the persistence of clonal NSA isolates. The A395T mutation in the ERG11gene was identified exclusively among azole resistant isolates. The use of corticosteroid was statistically associated with the occurrence of clonal NSA isolates. CONCLUSIONS: Candida parapsilosis(sensu stricto) remains the main species of the complex in bloodstream infections. Azole-resistant isolates with mutations in the ERG11gene are emerging in the two hospitals evaluated. Additionally, the correlation between the genotypes and the clinical data showed the occurrence of an outbreak involving isolates resistant to azoles, with a statistically significant association with previous use of corticosteroids. Candida parapsilosis(sensu stricto) was the only species that presented high biofilm formation and resistance against echinocandins. The two MALDI-TOF MS platforms differentiated the proteomic profiles of the planktonic and sessile cells of Candida parapsilosis, demonstrating the potential use of this technology to identify possible biofilm-specific therapeutic targets or biomarkers

Orientador: Ewerton Garcia de Oliveira Mima
Resumo: Um dos principais mecanismos de resistência microbiana são os sistemas de efluxo, que transportam medicamentos antimicrobiano para fora da célula. A eficácia de alguns agentes de inibição dos sistemas de efluxo tem sido reportada para reverter a resistência microbiana e também para potencializar as terapias antimicrobianas. Além disso, métodos alternativos aos agentes antimicrobianos convencionais têm sido investigados, como a Terapia Fotodinâmica antimicrobiana (aPDT). O objetivo desse estudo foi avaliar in vitro o efeito da aPDT e de dois inibidores de sistemas de efluxo microbiano (curcumina e verapamil) na resistência à inativação de C. albicans. Foram utilizadas duas cepas de C. albicans, uma susceptível (CaS) e outra resistente (CaR) a fluconazol. Os parâmetros de inativação fúngica foram determinados submetendo-se culturas planctônicas de ambas as cepas à curcumina, ao verapamil, ao fluconazol e também à aPDT (mediada pela curcumina 40 μM (14,73 μg/mL) e luz de LED azul de ≅455 nm a 5,28 J/cm2). As duas cepas foram cultivadas e tratadas associando-se os agentes de inibição do efluxo ao fluconazol em concentrações não letais. Os dados de UFC/mL foram analisados pelos testes paramétricos t de Student, ANOVA/Welch e post-hoc de Games-Howell e pelo teste não paramétrico de Mann-Whitney (α=0,05; n=12). Os resultados demostraram que aPDT promoveu uma redução significativa (p<0,001) de 4,5 e 4,42 log10 para CaS e CaR, respectivamente. Para CaS, os valores de Concentrações Ini... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: One of the major mechanisms of microbial resistance is the efflux systems, or efflux pumps, present in the plasma membrane of microorganisms that carry an antimicrobial drug out of the cell. The efficacy of some inhibitors of efflux systems has been reported to reverse microbial resistance, including C. albicans, and also to potentiate antimicrobial therapies. In addition, alternative methods to conventional antimicrobial agents have been investigated, such as antimicrobial Photodynamic Therapy (aPDT). The objective of this study was to evaluate in vitro the effect of aPDT and two inhibitors of microbial efflux systems (curcumina and verapamil) on the resistance to inactivation of C. albicans. For this, two strains of C. albicans, one susceptible (CaS) and another resistant (CaR) to fluconazol were used. Fungal inactivation parameters were determined by subjecting planktonic cultures of both strains to curcumina, verapamil, fluconazol, and also aPDT (mediated by curcumin at 40 μM (14.73 μg/mL) and blue LED light of ≅455 nm and 5.28 J/cm2). These strains were then cultured and treated associating one of the efflux inhibitors with fluconazole using non-lethal concentrations. For the statistical analysis, the normality and the homogeneity of variances were evaluated by the Shapiro-Wilk and Levene tests, respectively. Data were analyzed by Student's t-tests, Welch-corrected ANOVA and Games-Howell post-hoc and Mann-Whitney non-parametric test (α = 0.05) (n = 12). aPDT promoted a s... (Complete abstract click electronic access below)
Mestre

Discovery of new antifungal chemo-therapeutics for humans is limited by the large degree of conservation among eukaryotic organisms. In recent years, the histone acetyl-transferase Rtt109 was identified as the sole enzyme responsible for an abundant and important histone modification, histone H3 lysine 56 (H3K56) acetylation. In the absence of Rtt109, the lack of acetylated H3K56 renders yeast cells extremely sensitive to genotoxic agents. Consequently, the ability to sustain genotoxic stress from the host immune system is crucial for pathogens to perpetuate an infection. Because Rtt109 is conserved only within the fungal kingdom, I reasoned that Rtt109 could be a novel drug target. My dissertation first establishes that genome stability provided by Rtt109 and H3K56 acetylation is required for Candida albicans pathogenesis. I demonstrate that mice infected with rtt109 -/- cells experience a significant reduction in organ pathology and mortality rate. I hypothesized that the avirulent phenotype of rtt109 -/- cells is due to their intrinsic hypersensitivity to the genotoxic effects of reactive oxygen species (ROS), which are utilized by phagocytic cells of the immune system to kill pathogens. Indeed, C. albicans rtt109 -/- cells are more efficiently killed by macrophages in vitro than are wild-type cells. However, inhibition of ROS generation in macrophages renders rtt109 -/- and wild-type yeast cells equally resilient to killing. These findings support the concept that ability to resist genotoxic stress conferred by Rtt109 and H3K56 acetylation is a virulence factor for fungal pathogens and establish Rtt109 as an opportune drug- target for novel antifungal therapeutics. Second, I report the discovery of a specific chemical inhibitor of Rtt109 catalysis as the initial step in the development of a novel antifungal agent. We established a collaboration with the Broad Institute (Cambridge, MA) to perform a high-throughput screen of 300,000 compounds. From these, I identified a single chemical, termed KB7, which specifically inhibits Rtt109 catalysis, with no effect on other HAT enzymes tested. KB7 has an IC50 value of approximately 60 nM and displays noncompetitive inhibition regarding both acetyl-coenzyme A and histone substrates. With the genotoxic agent camptothecin, KB7 causes a synergistic decrease in C. albicans growth rate. However, this effect is only observed in an efflux-pump mutant, suggesting that this compound would be more effective if it were better retained intracellularly. Further studies through structure-activity relationship (SAR) modifications will be conducted on KB7 to improve its effective cellular concentration.

Although A. fumigatus strains are generally susceptible to azoles, recently, acquired resistance to a number of antifungal compounds has been reported, especially to triazoles possibly due to widespread clinical use of triazoles or through exposure to azole fungicides in the environment. The significant clinical problem of azole resistance has led to study the antifungal resistance mechanisms for developing effective therapeutic strategies. Of 230 clinical A. fumigatus isolates submitted during 2008 and 2009 to the Mycology Reference Centre Manchester, UK (MRCM), 64 (28%) were azole resistant and 14% and 20% of patients had resistant isolates, respectively. Among the resistant isolates, 62 of 64 (97%) were itraconazole resistant, 2 of 64 (3%) were only voriconazole resistant and 78% were multi-azole resistant. The gene encoding 14-α sterol demethylase (cyp51A) was analyzed in 63 itraconazole resistant (ITR-R) and 16 ITR-susceptible clinical and environmental isolates of A. fumigatus respectively. Amino acid substitutions in the cyp51A, the commonest known mechanism of azole resistance in A. fumigatus, were found in some ITR-R isolates. Fifteen different amino acid substitutions were found in the cyp51A three of which, A284T, M220R and M220W, have not been previously reported. In addition, several mutations were found in the cyp51A gene in one of the A. fumigatus environmental isolates. Importantly, a remarkably increased frequency of azole-resistant isolates without cyp51A mutations was observed in 43% of isolates and 54% of patients. Other mechanisms of resistance must be responsible for resistance. In order to assess the contribution of transporters and other genes to resistance, particular resistant isolates that did not carry a cyp51A mutation were studied. The relative expression of three novel transporter genes; ABC11, MFS56 and M85 as well as cyp51A, cyp51B, AfuMDR1, AfuMDR2 AfuMDR3, AfuMDR4 and atrF were assessed using real-time RT-PCR in both azole susceptible and resistant isolates, without cyp51A mutations. Interestingly, deletion of ABC11, MFS56 and M85 from a wild-type strain increased A. fumigatus susceptibility to azoles and these genes showed changes in expression levels in many ITR-R isolates. Most ITR-R isolates without cyp51A mutations showed either constitutive high-level expression of the three novel genes or induction of expression upon exposure to itraconazole. One isolate highly over-expressed cyp51B, a novel finding. Our results are most consistent with over-expression of one or more of these genes in ITR-R A. fumigatus without cyp51A mutations being at least partially responsible for ITR resistance. Multiple concurrent possible resistance mechanisms were found in some isolates. My work probably explains the mechanism(s) of resistance in A. fumigatus isolates with cyp51A mutations. Other ITR resistance mechanisms are also possible. To determine taxonomic relationships among A. fumigatus clinical and environmental isolates, the sequences of the ITS, β-tubulin, actin and calmodulin gene of 23 clinical and 16 environmental isolates were analyzed phylogenetically. Actin and calmodulin sequences proved to be good for species differentiation of A. fumigatus while both ITS, β-tubulin regions did not, in this dataset. Many cryptic species of A. fumigates (complex) were found. All environmental A. fumigates complex isolates were ITR susceptible and no cross resistance was found.