M. Reyes-Montes

Histoplasma capsulatum was isolated from the spleen of a first infected mara (Dolichotis patagonum) and from a second mara's liver and adrenal gland, both in the same colony at the Africam Safari, Puebla, Mexico. Studies of H. capsulatum isolates, using nested-PCR of a 100-kDa protein coding gene (Hcp100) fragment and a two-primer RAPD-PCR method, suggest that these isolates were spreading in the environment of the maras' enclosure. By using a Dot-ELISA method, sera from mice inoculated with three homogenates of soil samples from the maras' enclosed space developed positive brown spot reactions to a purified H. capsulatum antigen, which identified the probable source of the maras' infection.

Aspergillus section Nigri comprises a group of related species that include Aspergillus niger, A. welwitschiae, A. carbonarius, A. brasiliensis and A. tubingensis. Some of these species are morphologically very similar to A. niger but exhibit different patterns of susceptibility to antifungal agents; such is the case for A. tubingensis. Therefore, when diagnosing aspergillosis, it is important to identify the pathogen at the species level. This study aimed to identify the species of an Aspergillus spp. isolate (MM-82) obtained from a patient with a dermatosis localized to the right leg. The MM-82 isolate was examined for macro- and microscopic morphology, conidia size and thermotolerance, and a phylogenetic analysis of a benA gene segment was performed for molecular identification. Susceptibility to antifungals was determined using antifungal microdilution according to the methodology of European Society of Clinical Microbiology and Infectious Diseases (EUCAST). Based on its phenotypic characteristics and the phylogenetic analysis of the sequence of a benA gene segment, the MM-82 isolate was identified as A. tubingensis. This fungus did not show resistance to antifungal agents commonly used for treatment. This study demonstrated that A. tubingensis can cause skin infection; this constitutes the first report of a case of aspergillosis caused by A. tubingensis in Mexico.

Fungal antigens with good reactivity and specificity are essential for the immunodiagnosis of systemic mycoses. We give here data on crude and purified antigens of Histoplasma capsulatum, Coccidioidis immitis and Paracoccidioides brasiliensis from local strains and which are the more prevalent in Mexico. The crude antigens had good reactivity in precipitating and skin testing whereas the purified antigens (DPPC: deproteinized polysaccharide protein complex) had a higher specificity in more sensitive tests such as ELISA and complement fixation. Our efficiency analysis showed that the crude antigens are best for epidemiologic studies due to their low cost, easy handling and fast detection. The purified ones are suited to establish with more precision the diagnosis of systemic mycoses.

The classification of microbial strains is currently based on different typing methods, which must meet certain criteria in order to be widely used. Phenotypic and genotypic methods are being employed in the epidemiology of several fungal diseases. However, some problems associated to the phenotypic methods have fostered genotyping procedures, from DNA polymorphic diversity to gene sequencing studies, all aiming to differentiate and to relate fungal isolates or strains. Through these studies, it is possible to identify outbreaks, to detect nosocomial infection transmission, and to determine the source of infection, as well as to recognize virulent isolates. This paper is aimed at analyzing the methods recently used to type Histoplasma capsulatum, causative agent of the systemic mycosis known as histoplasmosis, in order to recommend those that yield reproducible and accurate results.

Histoplasma capsulatum was isolated from gut, lung, liver, and spleen of 17 of 208 captured bats belonging to 6 different genera and species. Three of the 17 infected bats were from the State of Guerrero and 14 were from the State of Morelos. All were adult bats: 6 males (1 Pteronotus parnellii, 2 Natalus stramineus, 2 Artibeus hirsutus, and 1 Leptonycteris nivalis) and 11 females (1 Myotis californicus, 1 Mormoops megalophylla, 8 A. hirsutus, and 1 L. nivalis). High rates of bat infection with H. capsulatum were found in the monitored sites of the State of Morelos. Histoplasma infection of N. stramineus, A. hirsutus, and L. nivalis should be considered as the first records in the world. The fungus isolated from infected bats was identified by its typical mycelial-phase morphology and by its yeast-phase conversion. Exoantigen production confirmed the fungal identification by the presence of specific precipitation lines in double immunodiffusion assays using human immune serum. Histo...

The present paper analyzes the histoplasmin electrophoretic profiles and the randomly amplified polymorphic DNA (RAPD) patterns of the fungus Histoplasma capsulatum isolated from Mexican patients with AIDS-associated histoplasmosis. Clinical isolates from Guatemala, Colombia, and Panama, as well as H. capsulatum isolates from different sources in nature, were also processed. All histoplasmin samples shared four antigenic fractions of 200, 49, 10.5, and 8.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). According to their percentage of relatedness, based on SDS-PAGE histoplasmin electrophoretic image analysis, H. capsulatum isolates were divided in two groups: group A contained all AIDS-associated isolates studied and two human reference strains from Mexican histoplasmosis patients without AIDS; group B included bat guano, infected bat, and cock excreta isolates from the State of Guerrero, Mexico, plus three human histoplasmosis strains from Guatemala, P...