Detection of constitutive molecules on Histoplasma capsulatum yeasts through single chain variable antibody fragments displayed in M13 phages.

A nonimmune library, containing single chain variable fragments (scFv) of immunoglobulin human genes displayed on the surface of M13 filamentous phages, was used to recognize molecules exposed on Histoplasma capsulatum yeasts' surface, during their growth in synthetic medium. The scFv clones were checked in their consistency by Dot-ELISA using HRP/anti-M13 conjugate, and they were tested to recognize molecules on H. Capsulatum yeasts' surface by ELISA in plates. Three out of 80 scFv cones (C2, C6, and C52) reacted consistently with H. capsulatum molecules, and they recognized molecules from both H. capsulatum morphologic phases. However, C6 and C52 clones reacted better with molecules on the surface of whole yeasts, with molecules from the yeasts' cell-wall extract, and with molecules released to the supernatant of the yeast culture. Mycelial supernatants from other fungi, as well as from a Mycobacterium filtrate, were not recognized by scFv phage monoclones. Monoclones C2, C6, and C52 recognized yeast molecules irrespective of the H. capsulatum strains used; the C6 clone revealed a specific immunohistochemistry reaction when tested against homologous and heterologous fungal infected tissues. The scFv clones isolated will be a useful toll to define the role of their target molecules in the host-parasite relationship of histoplasmosis.

Identification of the infectious source of an unusual outbreak of histoplasmosis, in a hotel in Acapulco, state of Guerrero, Mexico.

Three isolates of Histoplasma capsulatum were identified from mice lung, liver, and spleen inoculated with soil samples of the X hotel's ornamental potted plants that had been fertilized with organic material known as compost. The presence of H. capsulatum in the original compost was detected using the dot-enzyme-linked immunosorbent assay. Nested-PCR, using a specific protein Hcp100 coding gene sequence, confirmed the fungal identification associated with an unusual histoplasmosis outbreak in Acapulco. Although, diversity between the H. capsulatum isolate from the hotel and some clinical isolates from Guerrero (positive controls) was observed using random amplification of polymorphic DNA based-PCR, sequence analyses of H-anti and ole fragment genes revealed a high homology (92-99%) between them.

[Intraspecific chromosomal variability in human pathogenic fungi, especially in Histoplasma capsulatum]. / Variabilidad cromosómica intraespecífica en hongos patógenos de humanos, especialmente en Histoplasma capsulatum.

The ploidy, karyotype, and chromosome length polymorphism (CLP) of human pathogenic fungi were revised with emphasis on Histoplasma capsulatum, the causative agent of the systemic mycosis, histoplasmosis. Currently, different systems of gel electrophoresis are being used to determine fungal electrokaryotypes (EK). By renaturation kinetic and genomic reconstruction in H. capsulatum strains (G-186AS and Downs), estimated genome sizes of 23 and 32 Mb were determined for both strains, respectively. The haploid state was proposed for both strains, although aneuploidy was suggested for the Downs strain. Contour-clamped homogeneous electric field (CHEF), field inversion gel electrophoresis (FIGE), and Southern blot using different probes showed the presence of six to seven chromosomes in the Downs strain (low virulence), whereas four chromosomes were identified in the G-186B strain (high virulence). The use of these methods in the three major H. capsulatum reference strains (G-217B and Downs from the United States of America, G-186B from Panama) revealed distinct chromosome sizes, from 0.5 to 5.7 Mb, with CLP associated with chromosomes size and mobility. Recently, by CHEF, using 19 H. capsulatum isolates from Latin-America and the G-186B strain, five to seven chromosomes with 1.1 to 11.2 Mb molecular sizes were revealed, which again suggested CLP in H. capsulatum. However, to elucidate the EKs polymorphism in H. capsulatum and its relationship with the isolates phenotype more studies are needed to understand the mechanisms controlling ploidy variability.

Brote epidémico de dermatofitosis por Microsporum canis / Epidemic outbreak of dermatophytosis due to Microsporum canis

Se informa de un brote epidémico de dermatofitosis causado por Microsporum canis en 12 personas de la colonia Gudalupe Coatzachico, Ecatepec, Estado de México. Todos los paciente presentaron múltiples lesiones inflamatorias, pruriginosas, diseminadas principalmente a la cara y el cuello. Las observaciones sugieren que la fuente de infección fue un gato callejero. Ocho de los pacientes fueron tratados itraconazol a dosis de 100mg/día y cuatro con ketoconazol de aplicación local. Todos los pacientes presentaron cuaración clínica y micológica

Onicomicosis: diagnóstico etiológico y frecuencia en 282 casos / Onichomycosis: diagnosis and incidence

Con la finalidad de conocer la frecuencia de diferentes agentes etiológicos de las onicomicosis, se hizo un estudio en 442 pacientes que presentaban diagnóstico sugestivo de esta micosis en manos o en pies. En todos ellos se practicó examen directo y cultivo de las escamas. En 282 (63.8 por ciento) de estos pacientes se comprobó el diagnóstico micológico por examen microscópico directo y/o por cultivo. El 93.8 por ciento de los pacientes con onicomicosis fueron adultos, con predominio del sexo femenino (55.0 por ciento). T. rubrum fue el hongo más frecuente aislado como causa de onicomicosis, en el 66.8 por ciento. Los dermatofitos afectaron más las uñas de los pies, en tanto que las levaduras del género Candida fueron más comunes en las manos. La mayoría de los 282 casos de onicomicosis se diagnosticaron tanto por examen directo como por cultivo (55.8 por ciento); en 21 casos (7.4 por ciento) el diagnóstico se estableció por cultivo. Se discute la importancia del laboratorio de micología en el diagnóstico preciso de las micosis, señalando la utilidad del cultivo para conocer la taxonomía del hongo causante y para un mejor manejo clínico, epidemiológico y terapéutico del paciente