Queratitis por Absidia corymbifera en paciente inmunocompetente sin traumatismo corneal previo / Keratitis caused by Absidia corymbifera in an immunocompetent male with no corneal injuries

CASO CLÍNICO: Varón sano de 55 años sin antecedente de traumatismo corneal acude a urgencias por un infiltrado en el ojo izquierdo que responde parcialmente a tratamiento antibiótico tópico. Tras la introducción de corticoterapia tópica presenta un importante empeoramiento de la úlcera. El examen directo y la tinción de Gram permiten un rápido diagnóstico de las hifas de Absidia. Presenta buena respuesta al tratamiento combinado de anfotericina y posaconazol. DISCUSIÓN: Las queratitis por Zygomycetes son raras. Es rara la afectación de pacientes sanos sin antecedentes de traumatismo corneal. El tratamiento combinado de anfotericina y posaconazol ejerce un efecto sinergico contra hongos filamentosos

CASE REPORT: A healthy 55-years-old male went to emergency due to a white infiltrate in the left eye without corneal trauma which partially responds to antibiotic treatment. The infiltrate worsened by the use of topical steroids. Direct microscopic evaluation and Gram stain are a valuable diagnostic tool for the detection of Absidia filaments. There is a successful treatment with anphotericin and posaconazole. DISCUSSION: Keratitis caused by Zygomicetes are unusual. This is a rare condition in healthy patients with no corneal trauma. The treatment with amphotericin and posaconazole are synergistic against filamentous fungi

Revision of the genus Absidia (Mucorales, Zygomycetes) based on physiological, phylogenetic, and morphological characters; thermotolerant Absidia spp. form a coherent group, Mycocladiaceae fam. nov.

The genus Absidia comprises ubiquitously distributed soil fungi inhabiting different growth temperature optima ranging from 20-42 degrees C. Some of the mesophilic species are important biotechnologically in the biotransformation of steroids or as producers of rennin-like components, whereas species with higher growth temperature optima are of clinical relevance as opportunistic human pathogens. The aim of this study was to investigate the phylogenetic relationships between these species and to establish a revision of their systematics. For this purpose single and combined genealogies based on distance, MP, ML, and Bayesian analyses of aligned nucleotide sequences of the nuclear-encoded genes for actin (act) and for the 5.8S ribosomal RNA flanked by the ITS regions 1 and 2 (comprising 807 and 828 characters, respectively) of 16 Absidia species were reconstructed. The phylogenetic reconstructions suggest a trichotomy of the Absidia genus consisting of a mesophilic, a fast-growing thermotolerant, and a slowly-growing mycoparasitic Absidia group. The trichotomous phylogenetic grouping is concordant with the morphology of the zygospores, which are zygotes resulting from sexual conjugation between two compatible mating partners. Whereas the mesophilic group comprises the majority of absidiaceaeous species forming sterile hair-like, mycelial appendages on the suspensors of their zygospores, the thermotolerant group is characterised by the formation of smooth-walled zygospores, and the mycoparasitic group, namely Absidia parricida and A. zychae, by Mucor-like rough-walled zygospores. Based on the phylogenetic coherence of mesophilic and thermotolerant Absidia species, we propose that the two groups are separated into two distinct genera, Absidia for the mesophilic Absidia species resembling the Absidiaceae and Mycocladus for the thermotolerant species A. corymbifera, A. blakesleeana and A. hyalospora. Because Mycocladus is physiologically, phylogenetically, and morphologically distinct from the Absidiaceae s. str. we suggest that they are classified as a separate family, Mycocladiaceae fam. nov., which comprises the three species M. corymbifer, M. blakesleeanus and M. hyalospora.

Sexual reproduction in subcultures of Absidia blakesleeana after years of preservation under mineral oil.

Two subcultures of Absidia blakesleeana IOC No. 2425 (-) mating type strain preserved in 1959 and 1981 on a thick layer of potato dextrose agar (PDA) medium under sterile mineral oil and maintained at room temperature in the Fungal Cultural Collection of Institute Oswaldo Cruz--IOC--were paired with the defined Absidia blakesleeana URM-UFP No. 2076 (+) mating type strain. Portions of the line where mycelia of the two strains met were observed under light microscopy. Zygospores belonging to Subgenus Mycocladus were observed. The results demonstrated conservation and re-establishment of the physiological and genetic metabolic processes of two subcultures preserved under mineral oil.

Effect of supercritical fluids on C11beta-hydroxylation activity of Absidia coerulea.

The viability and C11beta-hydroxylation activity of Absidia coerulea were measured after treatment with compressed or supercritical CO2 and C2H4 under various initial pH and temperature conditions. The specific activity of A. coerulea on C11beta-hydroxylation can reach 23% and 75%, respectively, after treatment with 7.5 MPa of CO2 and C2H4, leading to the feasibility of enhancing both the solubility of the reactants and the beta-hydrocortisone yield for the hydroxylation of Reichsterin's substance acetate by using supercritical C2H4 as an alternative to the organic solvent.

Morphological observations on Absidia corymbifera and Absidia blakesleeana strains preserved under mineral oil.

Macro- and micromorphology of 30 living subcultures of Absidia corymbifera (10 strains plus three strains of Absidia ramosa) and Absidia blakesleeana (two strains) preserved under mineral oil at room temperature for periods ranging from 3 to 44 years in The Fungal Culture Collection of Instituto Oswaldo Cruz (IOC) were observed and described by permanent mycological preparations mounted in a glycerol 10% and/or Amann lactophenol solution. Vegetative and asexual reproductive structures are illustrated by drawings made with the aid of a camera-lucida. The study showed that the period of maintenance under mineral oil and the stress which took place during the period of storage did not affect the vegetative and asexual reproductive morphology of the Absidia strains and species studied here.