Identification of the causative dermatophyte of tinea capitis in children attending Mbarara Regional Referral Hospital in Uganda by PCR-ELISA and comparison with conventional mycological diagnostic methods.

Tinea capitis is a dermatophyte infection common among prepubertal children in sub-Saharan Africa and mainly caused by Trichophyton and Microsporum species. Accurate identification is challenging as conventional methods like culture and microscopy are slow and mostly based on morphological characteristics, which make them less sensitive and specific. Modern molecular methods, like polymerase chain reaction (PCR) assays, are gaining acceptance and are quick as well as accurate. The aim of this study was to investigate the clinical patterns of tinea capitis and to accurately identify the most common causative dermatophytes affecting the scalps of children aged 1 to 16 years attending the Skin Clinic at Mbarara University of Science and Technology (MUST), Mbarara, Uganda, East Africa, using both conventional mycological methods and PCR-ELISA for detection of dermatophyte DNA. One hundred fifteen clinical samples from children from Western Uganda attending the MUST Skin Clinic with a clinical diagnosis of tinea capitis were analyzed. T. violaceum was identified as the most common causative agent, followed by M. audouinii, T. soudanense, and T. rubrum. The early identification of the causative agent of tinea capitis is a prerequisite for the effective management of the disease, the identification of probable source and the prevention of spreading. Children with tinea capitis in Western Uganda should be treated by systemic therapy rather than topical preparations to ensure high cure rates as the most common causative dermatophytes T. violaceum exhibits an endothrix rather than ectothrix invasion of the hair follicle.

Unusual strains of Microsporum audouinii causing tinea in Europe.

We comment on an unusual strain of Microsporum (M.) audouinii. It was isolated from tinea corporis of a boy who lived in Germany and most likely had acquired his infection during a stay on a farm with animal husbandry in Poland. The strain showed features of M. canis (plenty of markedly rough-walled macroconidia, growth on rice, positive hair perforation) as well as of M. audouinii (white thallus, long macroconidia with central constriction) and in vitro it degraded hair of various mammals. Because its ribosomal internal transcribed spacer region showed 99.9% homology to a M. audouinii reference strain it was finally identified as M. audouinii. We relate these findings with recent observations of M. audouinii causing tinea in Europe. This appraisal suggests that irrespective of an identical ribosomal ITS region distinct M. audouinii strains can display a spectrum of morphological and physiological features that is broader than currently outlined in mycological textbooks. Certain unusual characteristics like an enhanced capacity to utilise keratins may even be associated with unexpected transmission routes. Above all sporadic M. audouinii infections in Europe that bear no relation to an endemic area should be analysed from this perspective.

Cat favus caused by Microsporum incurvatum comb. nov.: the clinical and histopathological features and molecular phylogeny.

Favus is a distinctive form of infection that is caused by exclusively dermatophytes. Its clinical presentation is characterized by scutula, which are concave, thick fungal crusts. The best-known examples of human scalp favus are caused by Trichophyton schoenleinii and those of mouse favus are caused by T. quinckeanum. However, other dermatophytes, such as T. violaceum, T. verrucosum, Microsporum audouinii, M. gallinae, M. gypseum, and M. canis, have been reported sporadically to cause favic lesions. Favus on cats has rarely been mentioned in the literature, and the pathogens with which it has been associated are, for the most part, unknown. Here, we examine four cat favus cases, focusing on clinical presentations and histopathological features. In all cases the etiologic agent was identified as M. incurvatum based on its morphological characteristics and sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. Phylogenetic analysis using the neighbor-joining method, which is based on ITS, showed that these four isolates belonged to two strains of M. incurvatum; one strain was a new combination from the basionym Nannizzia incurvata.

Standardization of hyphal growth inhibition rate as a means of evaluating Microsporum spp. in vitro susceptibility to terbinafine, griseofulvin, and ciclopiroxolamine.

Reference methods for antifungal susceptibility tests recommend the use of conidia as inoculum. However, some isolates produce few conidia, while the invasive form of filamentous fungi in general is hyphae making susceptibility tests infeaseble. These facts suggest that other than conidia broth dilution method is required for susceptibility tests. The aim of this study was to clarify if the hyphal growth inhibition rate could be used as a method of determining the antifungal susceptibility of genus Microsporum. For this reason, a method which traces hyphal tips automatically and measures their growth rate was standardized for Microsporum spp. Control growth curves and test growth curves obtained by real-time observation of the hyphae groups responses to different concentrations of terbinafine, griseofulvin, and ciclopiroxolamine were used to compare with minimum inhibitory concentrations (MICs) obtained by conidia broth microdilution method. A visible reduction in the growth inhibition rate was observed when hyphal activity was evaluated using the third or fourth serial two-fold dilution below the MIC determined by broth microdilution for terbinafine and ciclopiroxolamine. For griseofulvin, this reduction occurred after the fifth dilution below the MIC. This study highlights the importance of the inoculum type used to determine the in vitro susceptibility of Microsporum strains. We conclude that measurement of hyphal growth inhibition, despite being time consuming, could be a suitable method for evaluating antifungal susceptibility, particularly for fungi as Microsporum spp. that produce a small (or not at all) number of conidia.

Tinea corporis caused by an unusual strain of Microsporum audouinii that perforates hair in vitro.

We report on a dermatophyte infection acquired by a young woman from Germany who had worked in Ghana. The strain isolated from her skin lesions showed morphological and physiological features compatible with Microsporum audouinii but a clearly positive hair perforation test made its definite identification by conventional methods equivocal. A genetic analysis finally unambiguously revealed Microsporum audouinii. This is the first observation of a Microsporum audouinii strain with a positive hair perforation test. The ability to perforate hair may be related to attributes favouring an inflammatory host response.

First case of Microsporum ferrugineum from Tunisia.

This is the first case of Microsporum ferrugineum isolated from a Tunisian patient. A 60-year-old man was admitted for tinea sycosis associated with circinate herpes of the hand. Examination disclosed diffuse erythematic and perifollicular papules and pustules in the beard area. Typical ringworm vesiculo-pustular lesions involved skin of the hand. Isolates were identified as Microsporum sp on the basis of macroscopic and microscopic colony characteristics. The diagnosis of M. ferrugineum was confirmed by PCR sequencing of Chitin Synthase1 gene. The patient was treated successfully with Griseofulvin, which was administered for 4 weeks.

Glucose improves the in vitro viability of Microsporum canis and Trichophyton mentagrophytes var. mentagrophytes.

We describe simple and cost-effective methods using carbohydrates to improve the in vitro viability of dermatophytes. Glucose and sucrose in different concentrations (3, 6, 9 and 12%) were used to maintain fifteen strains of M. canis and T. mentagrophytes var. mentagrophytes at 4 and -20 degrees C. The strains were phenotypically analyzed before storage and reevaluated at 1, 3, 6 and 9 months. At 1 and 3 months, any alterations in the viability or phenotype pattern of the stored strains were noted. At 6 months, both dermatophytes were 100% viable, when preserved in glucose (3, 6, 9 and 12%) at -20 degrees C. All T. mentagrophytes strains were also viable in sucrose (12%), at 4 degrees C and -20 degrees C. However, sucrose failed to improve the viability of M. canis at both temperatures. At 9 months, the higher viabilities without pleomorphism were seen for both dermatophytes preserved in glucose (9 and 12%) at -20 degrees C.

Distribution of nuclei in macroconidia of Microsporum gypseum.

The distribution of nuclei in macroconidia was investigated in 20 strains of the dermatophyte Microsporum gypseum by fluorescence microscopy. The macroconidia were characterized by the right-left and the central-marginal symmetry indices. In 18 strains the significant majority of the nuclei were situated in the basal part of the macroconidium, the remaining 2 strains showed a more or less uniform distribution of nuclei. All strains had higher numbers of nuclei in the central part of the macroconidium as compared with the periphery.

[Ultrastructure of Nosema diplostomi - hyperparasite of the trematodes of the genus Diplostomum]. / Ul'trastruktura mikrosporidii Nosema diplostmi - giperparazita trematod roda Diplostomum.

Studies were undertaken of the fine structure of microsporidian, schizont, sporoblast and spore of Nosema diplostomi Schigina et Grobov, 1972 parasitic in metacercariae of fish eyes. The spore wall with outer membrane of the nuclear substance, polar filament, polaroplast, sporoplasm and rough endoplasmic reticulum are described. The diameter of a partially ejected filament is larger than the polar filament inside the spore.