Virginia M. Jewtuchowicz

Phenotypic and genotypic characterization of Aspergillus lentulus and Aspergillus fumigatus isolates in a patient with probable invasive aspergillosis.

Characteristic morphological and phylogenetic analyses demonstrated the presence of Aspergillus fumigatus and Aspergillus lentulus as the aetiological agents in a case of probable invasive aspergillosis (IA). This is believed to be the first report of an A. lentulus strain isolated from a patient with probable IA in Argentina.

Phenotypic and genotypic identification of Candida dubliniensis from subgingival sites in immunocompetent subjects in Argentina.

INTRODUCTION It is generally recognized that Candida dubliniensis is commonly found in immunocompromised patients, such as those with advanced human immunodeficiency virus infection, at sites of periodontal disease. Since there are no data available for Argentina, the aim of this study was to determine the prevalence of and to identify C. dubliniensis in periodontal pockets from immunocompetent subjects living in Buenos Aires, Argentina, through a comparison of phenotypic and molecular assays. METHODS Yeasts recovered from subgingival plaque samples were studied for 180 immunocompetent non-smoking patients with periodontal disease. Yeasts were identified by conventional mycological methods and by specific polymerase chain reaction (PCR) assay. Fluconazole and voriconazole susceptibility studies were performed in keeping with the Clinical and Laboratory Standards Institute. RESULTS Among 76 yeasts isolated, C. dubliniensis comprised 10.5% (n = 8; 95% confidence interval 4.7-19.7), which corresponded to 4.4% of patients studied (8/180). C. albicans was the most frequently isolated species of yeast. A great majority of C. dubliniensis isolates was susceptible with only one isolate resistant to both antifungals. CONCLUSION Micromorphology on Staib agar was the phenotypic method that was most concordant with PCR and it was useful for selecting presumptive C. dubliniensis. This is the first report to use PCR to identify C. dubliniensis in subgingival fluid from immunocompetent individuals with periodontal disease in Argentina. On the basis of the findings presented here, we confirm that C. dubliniensis can colonize periodontal pockets of immunocompetent patients with periodontal disease.

Phenotypic and genotypic characterisation of Candida dubliniensis isolate in a patient with disseminated candidiasis

Analia Fernandez, Virginia M. Jewtuchowicz, Maria Celina Malzone, Gabriela Lopez-Daneri, Gladys Saa, Cristina A. Iovannitti, Marta Tokumoto and Maria T. Mujica Laboratorio Central Servicio de Microbiologı́a, Hospital Universitario Fundación Favaloro, Buenos Aires, Argentina, Unidad de Cuidados Intensivos Pediátricos, Hospital Universitario Fundación Favaloro, Buenos Aires, Argentina and Departamento de Microbiologı́a, Parasitologı́a e Inmunologı́a de la Facultad de Medicina de la Universidad de Buenos Aires, Buenos Aires, Argentina

Estudio de la variabilidad genética entre aislamientos clínicos de Candida albicans formadores de biopelículas

Resumen Las biopeliculas estan constituidas por microcolonias incluidas dentro de una matriz polimerica y representan una forma de crecimiento microbiano. Candida albicans puede colonizar las superficies de cateteres, protesis y epitelios formando biopeliculas que son resistentes a las drogas antifungicas. El objetivo de este trabajo fue la caracterizacion genotipica de aislamientos clinicos de C. albicans formadores de biopeliculas usando la tecnica RAPD (Random Amplified Polymorphic DNA) . Fueron estudiados 25 aislamientos clinicos de C. albicans de fauces, sangre, piel, unas, materia fecal, biopsia de esofago, y flujo vaginal de pacientes con candidiasis. Cada cepa fue previamente analizada en su capacidad de crecer y adherirse a la superficie de poliestireno, y la cuantificacion de la biopelicula formada fue realizada mediante el ensayo de reduccion de XTT 2,3-bis (2-metoxi-4 nitro-5 sulfofenil) -2 H tetrazolio-5 carboxanilida.. Los coeficientes de similitud generados por RAPD variaron entre el 49 y el 91% con los cuatro iniciadores usados, revelando un alto nivel de variabilidad genetica. El dendrograma agrupo los aislamientos en cuatro grupos, incluyendo todos ellos cepas con muy diferente capacidad para formar biopeliculas. Aislamientos con genotipos similares mostraron diferente capacidad de formacion de biopeliculas. Las cepas fueron agrupadas independientemente del origen de la muestra. Nuestros resultados sugieren que en poblaciones naturales de C. albicans no existe correlacion entre la capacidad de formar biopeliculas y el genotipo determinado por PCR-RAPD.

Amplificación del gen CAP59 en Cryptococcus neoformans y Cryptococcus gattii directamente a partir de una suspensión de levaduras

Cryptococcus is an encapsulated yeast of class Basidiomycetes, etiologic agent of cryptococcosis. Cryptococcosis is one of the most common opportunistic infections in immunosuppressed patients, although it can affect immunocompetent individuals. In recent years, the identification of medically important fungal species has been achieved through the amplification of specific regions or genes of fungal DNA by polymerase chain reaction (PCR). The CAP59 gene is involved in the synthesis of the capsule in Cryptococcus neoformans and Cryptococcus gattii, and is useful in the molecular identification of serotypes. In this research, we use yeasts of different serotypes from collection strains and C. neoformans isolates recovered from patients with cryptococcosis. A standardized yeast suspension from different Cryptococcus isolates as template allowed CAP59 gene amplification. This procedure was quick, simple, and inexpensive and required no PCR steps. This is important for taxonomic studies in laboratories with implemented molecular biology tools.

Genetic relatedness of subgingival and buccal Candida dubliniensis isolates in immunocompetent subjects assessed by RAPD-PCR

Abstract Background: It is recognized that Candida dubliniensis commonly colonizes oral and subgingival sites in immunocompetent subjects with periodontal disease. Objective: Since there are few data available on genetic characterization of C. dubliniensis in periodontal pockets and other oral sites, the aim of this study was to characterize subgingival and mucosal C. dubliniensis isolates recovered from immunocompetent subjects and to assay the genetic similarity of such isolates from both niches in the same patient by random amplified polymorphic DNA (RAPD). Design: C. dubliniensis recovered from subgingival plaque and from buccal cavity samples were studied in 240 immunocompetent non-smoking individuals. Arbitrary amplification was carried out by RAPD-polymerase chain reaction (PCR). Results: RAPD analysis showed identical genotypes of C. dubliniensis in different sampling sites (buccal cavity and subgingival areas) in eight of 10 patients except for those derived from two participants who presented presumably unrelated isolates. Conclusions: On the basis of the findings presented, the origin of the colonization of C. dubliniensis in subgingival biofilm seems to be the buccal cavity in a single patient. Consequently, it may be assumed that most of C. dubliniensis in these sites arise from the endogenous commensal strains.