prog detail - International Mycological Association

PS2PS4 - 0593
Genetic diversity and detection of the neurotropic black yeast Exophiala dermatitidis.
M. Sudhadham1, G. S. de Hoog 1, A.H.G. Gerrits van den Ende 1, S. Prakitsin 2
1 Centraalbureau voor Schimmelcultures, Utecht, Netherlands, 2 Chulalongkorn University, Bangkok, Thailand
The black yeast Exophiala dermatitidis is an uncommon etiologic agent of fatal infections of the central nervous
system in otherwise healthy, mainly adolescent patients in East Asia. The route of infection is still a mystery. The steam
bath apparently provides a novel environmental opportunity for this fungus, but it is uncommonly distributed by air or
steam and thus inhalative infection from the steam bath is unlikely. Rapid screening of a diversity of environments is
therefore essential. Two preponderant ITS rDNA genotypes are known. It is our aim to enhance detection of the
genotypes in natural and human-dominated environments.
Strains were isolated by pre-incubation in Raulin’s solution, and subsequently on Erythritol-Chloramphenicol Agar
(ECA) at 40°C. Strains were purified with Tween 0.1%. For phenetic identification, assimilation of nitrate was tested.
Genotype-specific assays were developed using Amplified Fragment Length Polymorphism (AFLP), by Single-Strand
Confirmation Polymorphism (SSCP), by restriction analysis (RFLP) and by applying selective primers.
Growth at 40°C and absence of assimilation of nitrate separate Exophiala dermatitidis and E. phaeomuriformis from
all other black yeasts. An RFLP assay for detection of the preponderant genotypes and a genotype with a 30 bp Indel
in ITS1 was developed. Digestion with Taq I revealed two different types, by which the genotypes I and II could be
recognized easily. A third genotype was recognized by a small band shift. Genotype detection was enhanced by the
use of specific primers and SSCP. With AFLP a further subdivision of genotypes was possible.
RFLP combined with simple phenetic data enabled precise recognition of E. dermatitidis down to the genotype level.
Specific PCR assay enable detection without culturing. In combination the methods will enhance large-scale
screening of clinical and environmental samples
PS2PS5 - 0069
Outbreak of Tinea Corporis Gladiatorum in Tehran
Shahindokht Bassiri Jahromi, Ali Asghar Khaksar
Medical Mycology Department, Pasteur Institute of Iran
In recent years, skin diseases in wrestling have finally received the attention it deserves. Outbreaks of tinea corporis are
often associated with sports such as wrestling that involve extensive bodily contact. Tinea corporis gladiatorum,
caused in most by Triclophyton tonsurans, infect wrestlers at alarming rates. The management of skin infections in
wrestlers and other athletes in sports involving skin-to-skin contact is challenging, from making an accurate diagnosis
to determining eligibility for play. To control the outbreak, we conducted an epidemiologic investigation. The purpose
of this article is to determine the prevalence of tinea corporis gladiatorum in wrestlers club in Tehran.
A study of dermatophytosis among wrestlers was carried out during the period March 2001 to December 2005 in 612
mycologically proven cases of dermatophytosis in wrestlers in Tehran. The wrestler mycologically examination
consisting of direct microscopic observation and culture of pathologic material. Diagnosis was based on the macroand
microscopic characteristics of the colonies.
Trichophyton tonsurans was the predominant dermatophyte,accounting for >90% of all tinea corporis gladiatorum
isolates in each of the 5 years analysed.Tinea corporis gladiatorum was found to be more frequent in 10-30 age groups
(94.6%).The wrestlers with corporis gladiatorum were mostly from wrestler clubs in south and south-east of
Tehran.Transmission of tinea corporis is primarily through skin-to- skin contact.
The rapid identification and treatment of tinea corporis gladiatorum is vital to minimize disruption in team practices
and competition, are paramount. . Because infection with dermatophytes can disqualify a wrestler from competing
in matches, vigilant surveillance and rapid initiation of therapy can reduce the suspension of a team’s practice and
competition.
1015-1115 – 0762
PLENARY 4
Mating in fungi
Regina Kahmann
Germany
In my lecture I will give a brief overview of the conserved mating systems present in diverse groups of fungi and
describe how these loci determine cell identity and promote outbreeding. Special emphasis will be given to the
bipolar and tetrapolar mating systems of the Basidiomycetes where multiple specificities arise through recombination.
The developmental pathways which are regulated by the mating type genes will be outlined using the smut fungus
Ustilago maydis as prime example. In this organism the b mating type genes control morphogenesis and pathogenic
development. In their active form the b proteins exist as heterodimeric transcription factors that trigger a regulatory
cascade comprising about 250 genes. Many of these genes have unknown functions and this percentage is
especially high among genes whose products are predicted to be secreted. I will present evidence that some of these
novel proteins have essential functions during pathogenesis.
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