Antibacterial and synergistic activity of a new 8-hydroxyquinoline derivative against methicillin-resistant Staphylococcus aureus.

Aim: To evaluate the antibacterial and synergistic effect of a new 8-hydroxyquinoline derivative (PH176) against MRSA. Materials & methods: PH176 activity was determined by broth microdilution against 38 Staphylococcus aureus clinical isolates. The antibacterial and synergistic effects with oxacillin and nitroxoline were evaluated by time-kill assays to five MRSA isolates. Toxicity was evaluated by in vitro and ex vivo models. Results: The MIC50 and MIC90 of PH176 were 16 and 32 µg/ml, respectively. The PH176 and nitroxoline led to a reduction in colony count for four isolates and the combination of PH176 and oxacillin acted synergically for three isolates. Furthermore, PH176 was determined to be noncytotoxic/nonirritant. Conclusion: These results demonstrate that PH176 has revealed promising results to be a potential candidate to treat MRSA infections.

Structure-based design of δ-lactones for new antifungal drug development: susceptibility, mechanism of action, and toxicity.

Dermatophytes are the etiological agents of cutaneous mycoses, including the prevalent nail infections and athlete's foot. Candida spp. are opportunistic and emerging pathogens, causing superficial to deeper infections related to high mortality rates. As a consequence of prolonged application of antifungal drugs, the treatment failures combined with multidrug-resistance have become a serious problem in clinical practice. Therefore, novel alternative antifungals are required urgently. δ-Lactones have attracted great interest owing to their wide range of biological activity. This article describes the antifungal activity of synthetic δ-lactones against yeasts of the genus Candida spp. and dermatophytes (through the broth microdilution method), discusses the pathways by which the compounds exert this action (toward the fungal cell wall and/or membrane), and evaluates the toxicity to human leukocytes and chorioallantoic membrane (by the hen's egg test-chorioallantoic membrane). Two of the compounds in the series presented broader spectrum of antifungal activity, including against resistant fungal species. The mechanism of action was related to damage in the fungal cell wall and membrane, with specific target action dependent on the type of substituent present in the δ-lactone structure. The damage in the fungal cell was corroborated by electron microscopy images, which evidenced lysed and completely altered cells after in vitro treatment with δ-lactones. Toxicity was dose dependent for the viability of human leukocytes, but none of the compounds was mutagenic, genotoxic, or membrane irritant when evaluated at higher concentrations than MIC. In this way, δ-lactones constitute a class with excellent perspectives regarding their potential applications as antifungals.

Antifungal mechanism of action of Schinus lentiscifolius Marchand essential oil and its synergistic effect in vitro with terbinafine and ciclopirox against dermatophytes.

OBJECTIVES: The aim of this study was to evaluate the antifungal, antichemotactic and antioxidant activities of Schinus lentiscifolius essential oil, as well as its combined effect with terbinafine and ciclopirox, against dermatophytes. METHODS: Essential oil was analysed by GC-MS. The antifungal activity and the mechanism of action were determined by broth microdilution, sorbitol and ergosterol assays, as well as scanning electron microscopy. The checkerboard method was used for evaluating the interactions with commercial antifungal agents. The antioxidant and antichemotactic activities were measured using the DPPH and the modified Boyden chamber methods, respectively. KEY FINDINGS: Chemical analysis revealed the presence of 33 compounds, the primary ones being γ-eudesmol (12.8%) and elemol (10.5%). The oil exhibited 97.4% of antichemotactic activity and 37.9% of antioxidant activity. Antifungal screening showed effect against dermatophytes with minimum inhibitory concentration values of 125 and 250 µg/ml. Regarding the mechanisms of action, the assays showed that the oil can act on the fungal cell wall and membrane. Synergistic interactions were observed using the combination with antifungals, primarily terbinafine. CONCLUSIONS: Schinus lentiscifolius essential oil acted as a chemosensitizer of the fungal cell to the drug, resulting in an improvement in the antifungal effect. Therefore, this combination can be considered as an alternative for the topical treatment of dermatophytosis.

Multitask Imidazolium Salt Additives for Innovative Poly(l-lactide) Biomaterials: Morphology Control, Candida spp. Biofilm Inhibition, Human Mesenchymal Stem Cell Biocompatibility, and Skin Tolerance.

Candida species have great ability to colonize and form biofilms on medical devices, causing infections in human hosts. In this study, poly(l-lactide) films with different imidazolium salt (1-n-hexadecyl-3-methylimidazolium chloride (C16MImCl) and 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS)) contents were prepared, using the solvent casting process. Poly(l-lactide)-imidazolium salt films were obtained with different surface morphologies (spherical and directional), and the presence of the imidazolium salt in the surface was confirmed. These films with different concentrations of the imidazolium salts C16MImCl and C16MImMeS presented antibiofilm activity against isolates of Candida tropicalis, Candida parapsilosis, and Candida albicans. The minor antibiofilm concentration assay enabled one to determine that an increasing imidazolium salt content promoted, in general, an increase in the inhibition percentage of biofilm formation. Scanning electron microscopy micrographs confirmed the effective prevention of biofilm formation on the imidazolium salt containing biomaterials. Lower concentrations of the imidazolium salts showed no cytotoxicity, and the poly(l-lactide)-imidazolium salt films presented good cell adhesion and proliferation percentages with human mesenchymal stem cells. Furthermore, no acute microscopic lesions were identified in the histopathological evaluation after contact between the films and pig ear skin. In combination with the good morphological, physicochemical, and mechanical properties, these poly(l-lactide)-based materials with imidazolium salt additives can be considered as promising biomaterials for use in the manufacturing of medical devices.

Incidência de fungos anemófilos do gênero Aspergillus presentes no ar durante o período de reforma em ambiente hospitalar / Incidence of airborne spoilage fungi and identification from Aspergillus Genus present in hospital atmosphere during the period of reforms

Com o intuito de caracterizar a freqüência de fungos anemófilos do gênero em ambiente hospitalardurante o período de reformas, coletou-se o ar interno e externo do Centro de Terapia Intensivo (CTI) adulto e, o ar do centro cirúrgico, em dois diferentes pontos. O primeiro, há cerca de um metro da reforma e, o segundo ponto, há 10 metros de distância. As coletas foram realizadas em um hospital do oeste do estado de Santa Catarina, durante o mês de fevereiro de2008, nos períodos da manhã e da tarde, três vezes por semana. Foram coletadas 52 amostras, onde houve o isolamento de 323 colônias de fungos anemófilos, sendo que destes, 11 amostras (21%) continham colônias típicas de Aspergillus , dos quais nenhum era da espécie A. niger ou A. flavus , ou seja, as 32 colônias (10%) isoladas pertenciam exclusivamente à espécie A. fumigatus. A caracterização dos fungos de ambientes internos de áreas críticas de hospitais tem sido mundialmente reconhecida como importante medida visando reduzir substancialmente a morbidade, mortalidade e os altos custos hospitalares. O monitoramento de contaminantes ambientais em hospitais deve ser frequentemente realizado, principalmente em área especiais com pacientes imunocomprometidos, sujeitos à exposição de patógenos do meioambiente.

With the intention of characterizing the frequency of airborne spoilage fungi from Aspergillus genus in hospitalatmosphere during the period of reforms, was collected the internal and external air of adult Intensive Therapy Center (ITC) and the air of the surgical center, in two different places. The first, about a meter of the reform and the second point, there are 10 meters away. The collections were accomplished in the west hospital from Santa Catarina state, during the month of February of 2008, in the period of the morning and of the afternoon, three times a week. Starting from 52 samples, there was the isolation of 323 colonies of airborne fungi, and of these, 11 samples (21%) had typical colonies of Aspergillus genus, noneof which was the species A. niger or A. flavus, ie, the 32 colonies (10%) isolates belonged exclusively to the species A. fumigatus. The characterization of the moulds of internal atmospheres of critical areas of hospitals has globally been recognized as important measure seeking to reduce the morbidity, mortality and the high hospital costs substantially. This way, the environmental sources monitory should be realized, mainly in special rooms with immunosuppressed patient,subjects to the exhibition of pathogen environment.

Determinación de ocratoxina-a por HPLC con detección por fluorescencia (HPLC-FL): un nuevo método estandarizado para muestras de trigo / Ochratoxin-a determination by HPLC with fluorescence detection(HPLC-FL): a new standardization method for wheat samples

El objetivo principal de este estudio fue evaluar la presencia de Ocratoxina-A (OTA) en los granos del trigo y harina del trigo realizadas por un nuevo método de determinación que usa la cromatografía líquida de alta resolución (CLAR) acoplada al descubridor delfluorimetrio. El experimento usó seis muestras de grano de trigo del lugar del almacenamiento diferente a la industria local de Chapeco (SC), Brasil Sur, en agosto, 2008. El extracto de OTA era llevado a cabo usando el acetonitrila: agua (120:80 vlv) como solventes. Después el suprenadante fue filtrado, y aplicado en la columna del inmunoafinidad específica a OTA. Además, la columna se lavó con agua y la toxina era el eluido con el metanol. La determinación del OTA se realizó por detección de fluorescencia acoplado al aparato de HPLC. Los volúmenes de OTA en los granos del trigo y harina del trigo eran entonces los determínate y los resultados mostraron una concentración de OTA menor que los límites exigidos por la legislación internacional.

The main objective of this study was to evaluate the presence of Ochratoxin A (OTA) in wheat grains and wheat flour samples using a new high performance liquid chromatography (HPLC) method. The experiment used six wheat grain samples from different industry storage place from Chapeco (SC), South Brazil, on August 2008. The OTA extraction was carried out using acetonitrile: water (120:80 v/v) as solvent. Thereafter, the supernatant was filtered, and applied on OTA-specific immunoafinity column to HPLC Furthermore, the column was washed with water and the toxin was eluted with methanol. The OTA wheat grains and wheat flour concentration were analyzed by a fluorescence detector coupled to the HPLC apparatus. The results showed a smaller OTA concentration than the limits set by international legislation.

Investigation of the cytotoxicity of antimicrobial peptide P40 on eukaryotic cells.

The in vitro cytotoxicity of the antimicrobial peptide P40 was investigated. The food grade bacteriocin nisin was also analyzed for comparison. VERO cells were treated with different concentrations (0.02-2.5 microg ml(-1)) of nisin and P40, and cell viability and plasma membrane integrity were checked by MTT, neutral red uptake (NRU), and lactate dehydrogenase (LDH) assays. In MTT and NRU assays the EC(50) to the purified peptide P40 were 0.30 and 0.51 microg ml(-1), while values found to nisin were 0.35 and 0.79 microg ml(-1), respectively. In the LDH assay, the EC(50) was 0.57 and 0.62 microg ml(-1) for P40 and nisin, respectively. The peptide P40 revealed higher hemolytical activity (19%) when compared to nisin (4.9%) at the highest concentration tested (2.5 microg ml(-1)). Relatively few studies about the cytotoxicity of antimicrobial peptides are available. The determination of the cytotoxicity of antimicrobial peptides is an essential step to warrant their safe use.