Christiane Kupsch

For about 10 years, a new variant of the pathogen Trichophyton (T.) benhamiae has appeared in Germany, characterized by a previously unobserved culture phenotype with a strong yellow reverse. A few studies suggest that this new variety is now the most common zoophilic dermatophyte in Germany. The guinea pig is the main carrier. Exact prevalence measurements are not yet available. Thus, the aim of our ongoing study was to collect data on the frequency and geographic distribution of the pathogen and its phenotypes (white and yellow) in humans and guinea pigs throughout Germany. Our former studies have already shown that animals from large breeding farms are particularly heavily affected. In contrast to this, 21 small, private breedings were sampled and husbandry conditions recorded. This placed us in a position to identify propagation factors and to give recommendations for containment. For animals from private breedings, we detected T. benhamiae with a prevalence of 55.4%, which is a reduction of nearly 40% compared with animals from large breeding farms. As risk factors, we identified the type of husbandry and the contact to other breedings. Furthermore, certain animal races, like Rex guinea pigs and races with long hair in combination with curls were predestined for colonization with T. benhamiae due to their phenotypic coat characteristics. A prevalence for infections with T. benhamiae of 36.2% has been determined for symptomatic pet guinea pigs suspected of having dermatophytosis and is comparable to the study of Kraemer et al. showing a prevalence of 34.9% in 2009 in Germany. The prevalence in humans is stable with about 2–3% comparing the data of 2010–2013 and 2018 in Thuringia. The new type of T. benhamiae was by far the most frequent cause in all settings.

Zusammenfassung: Hintergrund: Ein erst kürzlich in zwei Studien beschriebener neuer Genotyp des zoophilen Dermatophyten Trichophyton (T.) mentagrophytes wurde von drei Patienten mit Südostasienaufenthalt und von einem Patienten nach dem Aufenthalt in Ägypten isoliert. Im Gegensatz zu diesen Publikationen haben wir hier eine Anzahl von Fällen in der Dimension eines Epidemieausbruchs beobachtet.Patienten und Methodik: An der Charité – Universitätsmedizin Berlin wurden zwischen Januar 2016 und Juli 2017 43 Patienten beobachtet, die überwiegend an hoch entzündlichen, schmerzhaften und hartnäckigen Infektionen der Pubogenitalregion litten. Die mykologische Untersuchung erfolgte mittels Pilzkultur und Sequenzierung der ITS‐Region (Internal Transcribed Spacer) der ribosomalen DNA. Drei weitere genomische Regionen wurden stichprobenartig sequenziert.Ergebnisse: In 37 der Fälle wurde der neue Genotyp der Spezies T. mentagrophytes (hier T. mentagrophytes VII genannt) als Verursacher isoliert. Die Sequenzierungen ergaben identische Sequenzen für alle Isolate. Die meisten der infizierten Patienten hatten keine Reiseanamnese, nur zwei Patienten berichteten von Tierkontakt.Schlussfolgerungen: Der neue Genotyp lässt sich phylogenetisch in vier verschiedenen DNA‐Markern der zoophilen Spezies T. mentagrophytes zuordnen. Während die Übertragung von zoophilen Dermatophyten von Mensch zu Mensch in der Regel selten ist, erfolgt die Übertragung hier scheinbar sehr effektiv über sexuellen Kontakt.

Summary: Background: A new genotype of the zoophilic fungal species Trichophyton (T.) mentagrophytes was recently described in two studies. It was isolated from three patients who had visited Southeast Asia and one patient who had visited Egypt. In contrast to these studies, we have observed a number of cases with the dimensions of an epidemic outbreak.Patients and methods: At the University Hospital Charité Berlin, 43 patients, mostly suffering from highly inflammatory, painful and persistent infections of the pubogenital region were observed between January 2016 and July 2017. Mycological examination was performed with fungal culture and sequencing of the ITS (internal transcribed spacer) region of the ribosomal DNA. Three additional genomic regions were spot‐checked.Results: In 37 of the cases, a new genotype of T. mentagrophytes (referred to here as T. mentagrophytes VII) was isolated as the etiological agent, and sequencing revealed identical sequences for all isolates. Most of the infected patients had no history of travel, and only two patients reported contact with animals.Conclusions: The new genotype clustered phylogenetically among the strains of the zoophilic species T. mentagrophytes with four different DNA markers. While human‐to‐human transmission of zoophilic dermatophytes is rare, transmission via sexual contact seemed to be quite effective here.