Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies.

All Malassezia species are lipophilic; thus, modifications are required in susceptibility testing methods to ensure their growth. Antifungal susceptibility of Malassezia species using agar and broth dilution methods has been studied. Currently, few tests using disc diffusion methods are being performed. The aim was to evaluate the in vitro susceptibility of Malassezia yeast against antifungal agents using broth microdilution and disc diffusion methods, then to compare both methodologies. Fifty Malassezia isolates were studied. Microdilution method was performed as described in reference document and agar diffusion test was performed using antifungal tablets and discs. To support growth, culture media were supplemented. To correlate methods, linear regression analysis and categorical agreement was determined. The strongest linear association was observed for fluconazole and miconazole. The highest agreement between both methods was observed for itraconazole and voriconazole and the lowest for amphotericin B and fluconazole. Although modifications made to disc diffusion method allowed to obtain susceptibility data for Malassezia yeast, variables cannot be associated through a linear correlation model, indicating that inhibition zone values cannot predict MIC value. According to the results, disc diffusion assay may not represent an alternative to determine antifungal susceptibility of Malassezia yeast.

Producción de fosfolipasa y proteinasa en cepas de Malassezia pachydermatis aisladas de perros con otitis y sin otitis / Phospholipase and proteinase production by Malassezia pachydermatis isolated in dogs with and without otitis

Antecedentes. Malassezia pachydermatis forma parte de la microbiota cutánea de perros y gatos. M. pachydermatis se ha asociado frecuentemente a otitis externa y dermatitis seborreicas, sobre todo en el perro, y con menor frecuencia en el gato. M. pachydermatis podría actuar como patógeno cuando existen alteraciones en los mecanismos físicos, químicos o inmunológicos de la piel. Se han identificado diversos factores de virulencia como la capacidad de producir estearasas, lipasas, lipooxigenasas, proteinasas, condroitinsulfatasas e hialuronidasas. Objetivos. Se ha estudiado la actividad fosfolipasa medida a pH 6,3 y la actividad proteinasa medida a pH 6,3 y pH 6,8 (pH de oídos de perros con otitis) de cepas de M. pachydermatis aisladas de perros con otitis y sin otitis. Métodos. Se ha estudiado la actividad fosfolipasa mediante un método semicuantitativo con yema de huevo y la actividad proteinasa mediante un método semicuantitativo con agar albúmina sérica bovina. Se ha realizado el estudio en 96 aislamientos de M. pachydermatis, 43 de ellos aislados de perros sin sintomatología clínica de otitis y 52 aislados de perros con otitis. Resultados. Se observó que el 75,8% de los aislamientos presentaron actividad fosfolipasa a pH 6,3 y el 81% presentaron actividad proteinasa medida a pH 6,3, y el 97,9% a pH 6,8. Se detectó una mayor actividad fosfolipasa en cepas aisladas de perros con otitis. Con respecto a la actividad proteinasa, esta fue mayor a pH 6,8. Conclusiones. Estos hallazgos sugieren que la actividad fosfolipasa podría jugar un papel importante en la invasión de los tejidos del hospedador, por lo menos en la otitis crónica canina. Con respecto a la actividad proteinasa, estos hallazgos podrían ayudar a mejorar la terapéutica de la otitis cuando está implicada M. pachydermatis en el proceso, ajustando a pH bajos los tratamientos aplicados (AU)

[Phospholipase and proteinase production by Malassezia pachydermatis isolated in dogs with and without otitis]. / Producción de fosfolipasa y proteinasa en cepas de Malassezia pachydermatis aisladas de perros con otitis y sin otitis.

BACKGROUND: Malassezia pachydermatis is part of the skin microbiota of dogs and cats. M. pachydermatis has been associated with external otitis and seborrhoeic dermatitis, reported more often in dogs than in cats. When the physical, chemical or immunological mechanisms of the skin are altered, M. pachydermatis could act as a pathogen. Thus, several virulence factors, such as the ability to produce esterase, lipase, lipoxygenase, protease, chondroitin sulphatase, and hyaluronidase, have been studied. AIMS: In the present study, we aim to identify the phospholipase activity measured at pH 6.3, and the proteinase activity measured at pH 6.3 and pH 6.8 (pH from ears of dogs with external otitis) of M. pachydermatis strains isolated from dogs with and without external otitis. METHODS: The phospholipase activity was measured using a semi-quantitative method with egg yolk, and the proteinase activity with a semi-quantitative method using bovine serum albumin agar. The study was performed on 96 isolates of M. pachydermatis, 43 isolated from dogs without clinical symptoms of otitis, and 52 isolated from dogs with otitis. RESULTS: In our study, 75.8% of the isolates showed phospholipase activity at pH 6.3, and 81 and 97.9% of them showed proteinase activity measured at pH 6.3 and 6.8, respectively. A higher phospholipase activity was detected in strains isolated from dogs with otitis. The proteinase activity was increased at a pH of 6.8 (97.9%) in comparison to a pH of 6.3 (81%). CONCLUSIONS: Our results suggest that the phospholipase activity may play an important role in the invasion of host tissues in chronic canine otitis cases. The proteinase activity results obtained in this study suggest that a reduction in the pH of the treatment may improve its efficacy in the resolution of M. pachydermatis otitis.

Sertaconazole nitrate shows fungicidal and fungistatic activities against Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum, causative agents of tinea pedis.

The fungistatic and fungicidal activities of sertaconazole against dermatophytes were evaluated by testing 150 clinical isolates of causative agents of tinea pedis, Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum. The overall geometric means for fungistatic and fungicidal activities of sertaconazole against these isolates were 0.26 and 2.26 µg/ml, respectively, although values were higher for T. mentagrophytes than for the others. This is the first comprehensive demonstration of the fungicidal activity of sertaconazole against dermatophytes.

Tinea capitis. Experiencia de 2 años en un hospital de pediatría de Buenos Aires, Argentina / Tinea capitis: two years experience in a paediatric hospital of Buenos Aires, Argentina

La tiña de cabeza (tinea capitis) es una dermatofitosis causada por hongos pertenecientes a los géneros Microsporum y Trichophyton, y constituye un importante problema sanitario en Argentina. El objetivo fue conocer la incidencia y la respuesta terapéutica en los pacientes que asistieron a la consulta en un hospital pediátrico de alta complejidad durante un período de 2 años de estudio. Se diagnosticaron 98 casos de tinea capitis y 13 de querion de Celso. Microsporum canis se aisló en el 61,28% de los casos. El rango de los valores de concentración mínima inhibitoria para fluconazol, itraconazol, voriconazol, terbinafina, ketoconazol y griseofulvina fueron, respectivamente, > 32: 0,06–4; < 0,015–2; < 0,015–0,25; 0,13–8, y de 0,06–128mg/ml(AU)

Tinea capitis is an infection caused by dermatophytes of the genera Microsporum and Trichophyton, and constitutes a major health problem in Argentina. The aim of the present study was to find out the incidence of those etiological agents and the therapeutic response in patients attending a High-Complexity Paediatric Hospital within a two-year period. A total of 98 tinea capitis were diagnosed, 13 of which were Celsus kerion. Microsporum canis was isolated in 61.28%. The range of values for minimum inhibitory concentrations were >32, 0,06–4; <0,015–2; <0,015–0.25; 0.13–8; 0.06–128mg/mL for fluconazole itraconazole, voriconazole, terbinafine, ketoconazole and griseofulvin, respectively(AU)

[Tinea capitis: two years experience in a paediatric hospital of Buenos Aires, Argentina]. / Tinea capitis. Experiencia de 2 años en un hospital de pediatría de Buenos Aires, Argentina.

Tinea capitis is an infection caused by dermatophytes of the genera Microsporum and Trichophyton, and constitutes a major health problem in Argentina. The aim of the present study was to find out the incidence of those etiological agents and the therapeutic response in patients attending a High-Complexity Paediatric Hospital within a two-year period. A total of 98 tinea capitis were diagnosed, 13 of which were Celsus kerion. Microsporum canis was isolated in 61.28%. The range of values for minimum inhibitory concentrations were >32, 0.06-4; <0.015-2; <0.015-0.25; 0.13-8; 0.06-128 microg/mL for fluconazole itraconazole, voriconazole, terbinafine, ketoconazole and griseofulvin, respectively.

Sertaconazole: updated review of a topical antifungal agent.

Sertaconazole is an imidazole-type antifungal agent that has shown considerable in vitro activity against pathogenic fungi. Various studies carried out in animal models, clinical and toxicologic trials have confirmed the value of sertaconazole in the topical treatment of superficial mycoses in dermatology and gynecology. After several years of clinical experience in the topical treatment of dermatophytosis and Tinea versicolor, the substance has been approved for gynecologic candidiasis in Europe. Sertaconazole has a wide action spectrum that includes yeasts and dermatophyte fungi, and it is also active against bacteria, mainly Gram-positive cocci, making it highly efficient in the treatment of polymicrobial infections. The recent approval of the molecule by the US Food and Drug Administration, and the appearance of a new formulation of sertaconazole for the treatment of onychomycoses on a weekly administrative basis, are all data relevant to the process of marketing the product.

Collaborative evaluation of optimal antifungal susceptibility testing conditions for dermatophytes.

A multicenter study was conducted to define the most suitable testing conditions for antifungal susceptibility of dermatophytes. Broth microdilution MICs of clotrimazole, itraconazole, and terbinafine were determined in three centers against 60 strains of dermatophytes. The effects of inoculum density (ca. 10(3) and 10(4) CFU/ml), incubation time (3, 7, and 14 days), endpoint criteria for MIC determination (complete [MIC-0] and prominent [MIC-2] growth inhibition), and incubation temperature (28 and 37 degrees C) on intra- and interlaboratory agreement were analyzed. The optimal testing conditions identified were an inoculum of 10(4) CFU/ml, a temperature of incubation of 28 degrees C, an incubation period of 7 days, and MIC-0.